CN104889379A

CN104889379A - Metal powder for powder metallurgy, compound, granulated powder, and sintered body

Info

Publication number: CN104889379A
Application number: CN201510091555.6A
Authority: CN
Inventors: 田村贵之; 中村英文
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2014-03-04
Filing date: 2015-02-28
Publication date: 2015-09-09
Anticipated expiration: 2035-02-28
Also published as: US20150252459A1; CN104889379B; JP6354592B2; JP2015180767A

Abstract

A metal powder for powder metallurgy contains Fe as a principal component, Cr in a proportion of 15% by mass or more and 26% by mass or less, Ni in a proportion of 7% by mass or more and 22% by mass or less, Si in a proportion of 0.3% by mass or more and 1.2% by mass or less, C in a proportion of 0.005% by mass or more and 0.3% by mass or less, Zr in a proportion of 0.01% by mass or more and 0.5% by mass or less, and Nb in a proportion of 0.01% by mass or more and 0.5% by mass or less. Further, the metal powder for powder metallurgy preferably has an austenite crystal structure.

Description

Metal powder for powder metallurgy, compound, prilling powder and sintered body

Technical field

The present invention relates to metal powder for powder metallurgy, compound, prilling powder and sintered body.

Background technology

In powder metallurgic method, the constituent containing metal dust and adhesive is configured as desired shape and after obtaining formed body, by carrying out degreasing, sintering to formed body, thus produces sintered body.In the manufacture process of such sintered body, the particle of metal dust produces the diffusion phenomena of atom each other, and formed body is gradually densified and complete sintering thus.

Such as, in patent document 1, propose a kind of metal powder for powder metallurgy, containing Zr and Si, remainder is made up of at least one selected in the group formed from Fe, Co and Ni and inevitable element.According to such metal powder for powder metallurgy, the effect due to Zr makes agglutinating property improve, thus can easily manufacture highdensity sintered body.

The sintered body so obtained is being widely used in various mechanical part and structure member etc. in recent years.

But, according to the purposes of sintered body, sometimes also require more densified.Now, although by carrying out hip treatment (HIP process) such additional treatments further to sintered body thus realizing densification, while workload significantly increases, high cost is also inevitable.

Therefore, to when not applying additional treatments, the expectation realizing producing the metal dust of highdensity sintered body improves constantly.

At first technical literature

Patent document

Patent document 1: Japanese Patent Laid-Open 2012-87416 publication

Summary of the invention

The object of the present invention is to provide metal powder for powder metallurgy, compound and the prilling powder that can manufacture highdensity sintered body, and the highdensity sintered body using above-mentioned metal powder for powder metallurgy and manufacture.

Above-mentioned purpose is realized by following the present invention.

Metal powder for powder metallurgy of the present invention, is characterized in that, Fe is main component; Cr containing the following ratio of more than 15 quality % 26 quality %; Ni containing the following ratio of more than 7 quality % 22 quality %; Si containing the following ratio of more than 0.3 quality % 1.2 quality %; C containing the following ratio of more than 0.005 quality % 0.3 quality %; Zr containing the following ratio of more than 0.01 quality % 0.5 quality %; And the Nb containing the following ratio of more than 0.01 quality % 0.5 quality %.

Thereby, it is possible to realize alloy composition optimization, and can promote metal powder for powder metallurgy sinter time densified.Its result, when not applying additional treatments, can obtain the metal powder for powder metallurgy that can manufacture highdensity sintered body.

In metal powder for powder metallurgy of the present invention, preferably there is austenitic crystal structure.

Thereby, it is possible to give highly corrosion resistant and high-elongation to the sintered body manufactured.That is, although can obtain manufacturing is the metal powder for powder metallurgy that high density still has the sintered body of highly corrosion resistant and high-elongation.

In metal powder for powder metallurgy of the present invention, be preferably less than more than 0.3 3 relative to the ratio Zr/Nb of the containing ratio of the Zr of the containing ratio of Nb.

Thus, when burning till metal powder for powder metallurgy, can the timing offset of the precipitation of optimization Nb carbide and the precipitation of Zr carbide.Its result, owing to discharging while the emptying aperture remained in formed body can be scanned out successively from inner side, so can suppress the emptying aperture generated in sintered body for Min..Therefore, it is possible to obtain producing high density and the metal powder for powder metallurgy of the sintered body of sintered body excellent.

In metal powder for powder metallurgy of the present invention, the total of the containing ratio of Zr and the containing ratio of Nb is preferably below more than 0.05 quality % 0.6 quality %.

Thus, the sintered body of manufacture becomes densification necessity and sufficient sintered body.

In metal powder for powder metallurgy of the present invention, be more preferably the Mo containing the following ratio of more than 1 quality % 5 quality %.

Thereby, it is possible to do not cause the density of the sintered body of manufacture significantly to reduce, thus can the corrosion resistance of more intensified-sintered body.

In metal powder for powder metallurgy of the present invention, average grain diameter is preferably more than 0.5 μm less than 3.0 μm.

Thus, because emptying aperture remaining in sintered body becomes few, so special high density can be produced and the sintered body of mechanical performance excellence.

Compound of the present invention, is characterized in that, contains: metal powder for powder metallurgy of the present invention; And by adhesive that the particle of above-mentioned metal powder for powder metallurgy is bonded to each other.

Thereby, it is possible to obtain the compound that can manufacture highdensity sintered body.

Prilling powder of the present invention, is characterized in that, is formed by carrying out granulation to metal powder for powder metallurgy of the present invention.

Thereby, it is possible to obtain the prilling powder that can manufacture highdensity sintered body.

Sintered body of the present invention, is characterized in that, obtained by sinter powder metal metal dust, the main component of this metal powder for powder metallurgy is Fe; Cr containing the following ratio of more than 15 quality % 26 quality %; Ni containing the following ratio of more than 7 quality % 22 quality %; Si containing the following ratio of more than 0.3 quality % 1.2 quality %; C containing the following ratio of more than 0.005 quality % 0.3 quality %; Zr containing the following ratio of more than 0.01 quality % 0.5 quality %; And the Nb containing the following ratio of more than 0.01 quality % 0.5 quality %.

Thus, when not applying additional treatments, also can obtain highdensity sintered body.

Sintered body of the present invention preferably includes in graininess and the relatively high first area of the containing ratio of silica; And the second area that the containing ratio of silica is relatively lower than above-mentioned first area.

Thereby, it is possible to the oxide concentration realizing crystals reduces, and realize the remarkable growth suppressing crystal grain, can high density be obtained and the sintered body of mechanical performance excellence.

Detailed description of the invention

Below, metal powder for powder metallurgy of the present invention, compound, prilling powder and sintered body are described in detail.

Metal powder for powder metallurgy

First, metal powder for powder metallurgy of the present invention is described.

In powder metallurgy, after the constituent containing metal powder for powder metallurgy and adhesive is configured as desired shape, carries out degreasing, sintering, thus the sintered body of desired shape can be obtained.According to such PM technique, compared with other metallurgical technology, have and under near net-shaped shape, (shape close to net shape) complexity can be produced and the advantage of the sintered body of fine shape.

As the metal powder for powder metallurgy for powder metallurgy, in prior art, by suitably changing its composition, constantly attempt the densification realizing the sintered body manufactured.But, because sintered body easily forms emptying aperture, so in order to obtain the mechanical performance identical with ingot, need sintered body to realize further densification.

Therefore, in prior art, by applying the additional treatments such as hip treatment (HIP process) further to the sintered body obtained, thus realize densification.But, such additional treatments due to along with a large amount of energy and cost, so become obstacle when expanding sintered body purposes.

In view of the above-mentioned problems, the condition that the present inventor obtains highdensity sintered body to not applying additional treatments has carried out repeatedly studying.Its result, by the composition of the alloy forming metal dust is carried out optimization, thus finds the composition that can realize the densification of sintered body, completes the present invention.

Specifically, metal powder for powder metallurgy of the present invention is following metal dust: the Cr containing the following ratio of more than 15 quality % 26 quality %; Ni containing the following ratio of more than 7 quality % 22 quality %; Si containing the following ratio of more than 0.3 quality % 1.2 quality %; C containing the following ratio of more than 0.005 quality % 0.3 quality %; Zr containing the following ratio of more than 0.01 quality % 0.5 quality %; Nb containing the following ratio of more than 0.01 quality % 0.5 quality %; Remainder is made up of Fe and other elements.According to such metal dust, realize the optimized result of alloy composition, densified when can improve sintering especially.Its result, when not applying additional treatments, can manufacture highdensity sintered body.

And, by realizing the densification of sintered body, the sintered body of mechanical performance excellence can be obtained.Such sintered body also can be applicable to the purposes of this applying external force (load) of such as mechanical part and structure member widely.

Below, the alloy composition of metal powder for powder metallurgy of the present invention is described in detail further.In addition, in the following description, sometimes metal powder for powder metallurgy is called " metal dust " simply.

Cr (chromium) gives the element of corrosion resistance to the sintered body manufactured, and by using the metal dust containing Cr, can obtain can the sintered body of long term maintenance high-mechanical property.

In metal dust, the containing ratio of Cr is below more than 15 quality % 26 quality %, is preferably below more than 15.5 quality % 25 quality %, is more preferably below more than 16 quality % 21 quality %, more preferably below more than 16 quality % 20 quality %.When the containing ratio of Cr is lower than above-mentioned lower limit, according to the composition of entirety, the corrosion resistance of the sintered body of manufacture becomes insufficient.On the other hand, when the containing ratio of Cr exceedes above-mentioned higher limit, according to the composition of entirety, agglutinating property reduces, and the densification of sintered body becomes difficulty.

In addition, according to the containing ratio of aftermentioned Ni and Mo, the containing ratio preferred scope further of regulation Cr.Such as, the containing ratio of Ni is below more than 7 quality % 22 quality %, and, when the containing ratio of Mo is less than 1.2 quality %, containing ratio more preferably below more than the 18 quality % 20 quality % of Cr.On the other hand, the containing ratio of Ni is below more than 10 quality % 22 quality %, and, the containing ratio of Mo when below more than 1.2 quality % 5 quality %, the containing ratio of Cr more preferably more than 16 quality % and be less than 18 quality %.

Ni is the element sintered body manufactured being given to corrosion resistance and heat resistance equally.

In metal dust, the containing ratio of Ni is below more than 7 quality % 22 quality %, is preferably below more than 7.5 quality % 17 quality %, is more preferably below more than 8 quality % 15 quality %.By being set in above-mentioned scope by the containing ratio of Ni, the sintered body of long-term mechanical properties excellence can be obtained.

In addition, when the containing ratio of Ni is lower than above-mentioned lower limit, according to the composition of entirety, the corrosion resistance and the heat resistance that there is the sintered body manufactured can not by the possibilities fully improved, on the other hand, when the containing ratio of Ni exceedes above-mentioned higher limit, there is the possibility that corrosion resistance and heat resistance reduce on the contrary.

Si (silicon) is the element sintered body manufactured being given to corrosion resistance and high-mechanical property, and by using the metal dust containing Si, can obtain can the sintered body of long term maintenance high-mechanical property.

In metal dust, the containing ratio of Si is below more than 0.3 quality % 1.2 quality %, is preferably below more than 0.4 quality % 1 quality %, is more preferably below more than 0.5 quality % 0.9 quality %.When the containing ratio of Si is lower than above-mentioned lower limit, according to the composition of entirety, because the effect of adding Si becomes not enough, so the corrosion resistance of the sintered body manufactured and mechanical performance reduce.On the other hand, when the containing ratio of Si exceedes above-mentioned higher limit, according to the composition of entirety, because Si becomes too much, corrosion resistance and mechanical performance reduce on the contrary.

C (carbon), by with aftermentioned Zr and Nb and use, can improve agglutinating property especially.Specifically, Zr and Nb, by being combined with C respectively, generates the carbide such as ZrC and NbC.The carbide dispersion such by this Zrc and NbC is separated out, and produces the effect preventing crystal grain from significantly increasing.Although the clear and definite reason that can obtain this effect is failed to understand, as one of reason, can consider that the precipitate after due to dispersion becomes obstacle and hinders the remarkable growth of crystal grain, so inhibit the deviation of the size of crystal grain.Thus, owing to being difficult to generate emptying aperture in sintered body, and prevent the expansion of crystal grain, therefore, it is possible to obtain high density and the high sintered body of mechanical performance.

In metal dust, the containing ratio of C is below more than 0.005 quality % 0.3 quality %, is preferably below more than 0.008 quality % 0.15 quality %, is more preferably below more than 0.01 quality % 0.08 quality %.When the containing ratio of C is lower than above-mentioned lower limit, according to the composition of entirety, crystal grain becomes easy growth, and the mechanical performance of sintered body becomes insufficient.On the other hand, when the containing ratio of C exceedes above-mentioned higher limit, according to the composition of entirety, because C becomes too much, agglutinating property reduces on the contrary.

Zr (zirconium) is although form low melting point phase relative to Fe solid solution, and this low melting point causes atoms permeating fast when the sintering of metal dust.Further, this atoms permeating becomes driving force makes the grain spacing of metal dust from shrinking rapidly, between particle, form neck.Its result, the densified continuous progress of formed body, Fast Sintering.

On the other hand, the atomic radius of Zr is slightly larger than the atomic radius of Fe.Specifically, the atomic radius of Fe is approximately 0.117nm, and the atomic radius of Zr is approximately 0.145nm.Therefore, although Zr is relative to Fe solid solution, do not reach complete solid solution, the Zr of a part is as Zr carbide or ZrO such as ZrC ₂separate out Deng Zr oxide (below, being collectively referred to as " Zr carbide ").And can think, when metal powder sintered, the Zr carbide etc. of this precipitation hinders the remarkable growth of crystal grain.Its result, as mentioned above, is difficult to generate emptying aperture, and prevents the expansion of crystal grain in sintered body, can obtain high density and the high sintered body of mechanical performance.

In addition, details is aftermentioned, and the Zr carbide of precipitation etc. are in the accumulation of crystal boundary accelerating oxidation silicon, and its result, had both inhibit the expansion of crystal grain, achieved again promotion and the densification of sintering.

In addition, because Zr is ferrite former, so separate out body-centered cubic lattic phase.This body-centered cubic lattic due to the crystal lattice phase sintering than other excellent, so contribute to the densification of sintered body.

In addition, Zr is played a role by the deoxidier of the oxygen contained as oxide as removing in metal dust.Thereby, it is possible to make the oxygen containing ratio becoming the reason that agglutinating property reduces reduce, the densification of sintered body can be improved further.

In metal dust, the containing ratio of Zr is below more than 0.01 quality % 0.5 quality, is preferably below more than 0.03 quality % 0.2 quality %, is more preferably below more than 0.05 quality % 0.1 quality %.When the containing ratio of Zr is lower than above-mentioned lower limit, according to the composition of entirety, because the effect of adding Zr becomes not enough, so the densification of the sintered body manufactured becomes insufficient.On the other hand, when the containing ratio of Zr exceedes above-mentioned higher limit, according to the composition of entirety, because Zr is too much, so the ratio of above-mentioned carbide becomes too much, damage densification on the contrary.

The atomic radius of Nb (niobium) is also slightly large than the atomic radius of Fe, but more smaller than the atomic radius of Zr.Specifically, the atomic radius of Fe is approximately 0.117nm, and the atomic radius of Nb is approximately 0.134nm.Therefore, the Nb of a part is as Nb carbide or Nb such as NbC ₂o ₅separate out Deng Nb oxide (below, being collectively referred to as " Nb carbide ").Therefore can think, when sintering, Zr carbide etc. are separated out respectively with Nb carbide etc., and these precipitates hinder the remarkable growth of crystal grain, and in the accumulation of crystal boundary accelerating oxidation silicon.

On the other hand, the precipitation of such Zr carbide etc. and Nb carbide etc., with the precipitated phase ratio of Nb carbide etc., the precipitation of Zr carbide etc. starts at more low-temperature region.Although its reason is indefinite, can think relevant with the difference of the atomic radius of Zr and Nb.Further, different by the temperature province of such Carbide Precipitation, infer when metal powder sintered, the effect that the precipitation of Nb carbide etc. produces and Zr carbide etc. are separated out and are produced deviation the opportunity that the effect that produces embodies.Can think because the opportunity of such Carbide Precipitation produces deviation, the generation in cavity can be suppressed, and fine and close sintered body can be obtained.That is, can think because Nb carbide etc. exists with the both sides of Zr carbide etc., densification can be realized, and suppress the expansion of crystal grain.

In metal dust, the containing ratio of Nb is below more than 0.01 quality % 0.5 quality %, is preferably below more than 0.03 quality % 0.2 quality %, is more preferably below more than 0.05 quality % 0.1 quality %.When the containing ratio of Nb is lower than above-mentioned lower limit, according to the composition of entirety, because the effect of adding Nb becomes not enough, so the densification of the sintered body manufactured becomes insufficient.On the other hand, when the containing ratio of Nb exceedes above-mentioned higher limit, according to the composition of entirety, because Nb becomes too much, so the ratio of above-mentioned carbide becomes too much, lose densification on the contrary.

In addition, when the ratio of the containing ratio of the Zr of the containing ratio relative to Nb is set to Zr/Nb, Zr/Nb is preferably less than more than 0.3 3, is more preferably less than more than 0.5 2.By Zr/Nb being set in above-mentioned scope, can the deviation on opportunity of precipitation of precipitation and Zr carbide etc. of optimization Nb carbide etc.Thus, owing to can discharge with scanning out successively from inner side by the cavity remained in formed body, so the cavity produced in sintered body can be suppressed to Min..Therefore, by Zr/Nb being set as in above-mentioned scope, can obtain manufacturing high density and the metal dust of the sintered body of mechanical performance excellence.

In addition, the containing ratio of Zr and the containing ratio of Nb are respectively as mentioned above, the total of these containing ratios is preferably below more than 0.05 quality % 0.6 quality %, is more preferably below more than 0.10 quality % 0.48 quality %, more preferably below more than 0.12 quality % 0.24 quality %.By being set in above-mentioned scope by the total of the containing ratio of Zr and the containing ratio of Nb, the densification of the sintered body of manufacture becomes necessary and fully.

In addition, when the total of the containing ratio of Zr and the containing ratio of Nb is set to (Zr+Nb)/Si relative to the ratio of the containing ratio of Si, (Zr+Nb)/Si is preferably less than more than 0.1 0.7, is more preferably less than more than 0.15 0.6, and more preferably less than more than 0.2 0.5.By being set in above-mentioned scope by (Zr+Nb)/Si, fully compensate for the toughness reduction etc. when adding Si by the interpolation of Zr and Nb.Its result, although be high density, also can obtain manufacturing this mechanical performance of toughness excellent, and results from the metal dust of the also excellent sintered body of the corrosion resistance of Si.

In addition, can think by adding Zr and Nb in right amount, the crystal boundary in sintered body, Zr carbide as above etc. and Nb carbide as above etc. become " core ", and the accumulation of silica occurs.Crystal boundary is accumulated in, because the oxide concentration of crystallization inside reduces, so realize acceleration of sintering by silica.Its result, can think the densification of further acceleration of sintering body.

Further, the silica of precipitation moves due to the three phase point easily to crystal boundary in cumulative process, therefore inhibits the crystal growth (pinning effect) at this point.Its result, can suppress the remarkable growth of crystal grain, obtain having the sintered body of more fine crystal.Such sintered body has extra high mechanical performance.

In addition, the silica of accumulation is easily positioned at the three phase point of crystal boundary as mentioned above, therefore, exists and is configured as granular tendency.Therefore, at sintered body, easily form first area and second area, this first area formed such graininess, silica containing ratio relatively high, second area is relatively lower than the containing ratio of the silica of first area.Owing to there is first area, as mentioned above, the oxide concentration that can realize crystallization inside reduces and suppresses the remarkable growth of crystal grain.

In addition, at first area and second area, when carrying out qualitative and quantitative analysis respectively by electron beam microscopic analyzer (EPMA), in first area, O (oxygen) becomes essential element, and at second area, Fe becomes essential element.As mentioned above, first area is mainly present in crystal boundary, and second area is present in crystallization inside.Therefore, in first area, when comparing the containing ratio sum of O and Si two element and the containing ratio of Fe, the containing ratio sum of two elements is more than the containing ratio of Fe.On the other hand, at second area, the containing ratio sum of O and Si two element is littlely more absolute than the containing ratio of Fe.It can thus be appreciated that, realize the accumulation of Si and O in the first region.Specifically, in first area, the containing ratio of Si and the containing ratio sum of O are preferably more than 1.5 times less than 10000 times of the containing ratio of Fe.In addition, the containing ratio of the Si in first area is preferably more than 3 times less than 10000 times of the containing ratio of Si in second area.

Further, although there is different situations according to proportion of composing, at least one party in the containing ratio of Zr and the containing ratio of Nb meets the relation of first area > second area.Following situation is shown thus: in first area, above-mentioned Zr carbide etc. and Nb carbide etc. become core during carborundum accumulation.As concrete example, in first area, the containing ratio of Zr is preferably more than 3 times less than 10000 times of the containing ratio of Zr in second area.Same, in first area, the containing ratio of Nb is preferably more than 3 times less than 10000 times of the containing ratio of Nb in second area.

In addition, can think that the accumulation of silica as above is a densified reason of sintered body.Therefore can think, even the sintered body of the densification according to the present invention's realization, according to proportion of composing, also to there is the situation that silica does not accumulate.

In addition, although the diameter forming granular first area is different along with the Si containing ratio in sintered body entirety, be all approximately more than 0.5 μm less than 15 μm, be preferably about more than 1 μm less than 10 μm.Thereby, it is possible to suppress to reduce along with the mechanical performance of the sintered body of the accumulation of silica, and can the densification of abundant acceleration of sintering body.

In addition, the diameter of first area, in the electron micrograph in the cross section of sintered body, can try to achieve with the mean value of the area diameter of a circle of the same area (equivalent circle diameter) according to the deep or light first area determined as having.The measured value of more than 10 is used when averaging.

And, when the total of the containing ratio of Zr and the containing ratio of Nb is set to (Zr+Nb)/C relative to the ratio of the containing ratio of C, (Zr+Nb)/C is preferably less than more than 1 16, is more preferably less than more than 2 13, and more preferably less than more than 3 10.By being set in above-mentioned scope by (Zr+Nb)/C, the hardness can taken into account when adding C rises and the reduction of toughness and the densification that brought by the interpolation of Zr and Nb.Its result, can obtain the metal dust of the sintered body that can manufacture tensile strength and this mechanical performance excellence of toughness.

Metal powder for powder metallurgy of the present invention, as required can containing at least one in Mn, Mo, Cu, N and S except these elements.In addition, sometimes also inevitably containing these elements.

Mn and Si is identical, is the element sintered body manufactured being given to corrosion resistance and high-mechanical property.

In metal dust Mn containing ratio and be not particularly limited, be preferably below more than 0.01 quality % 3 quality %, more preferably below more than 0.05 quality % 1 quality %.By being set in above-mentioned scope by the containing ratio of Mn, high density can be obtained and the sintered body of mechanical performance excellence.

In addition, when the containing ratio of Mn is lower than above-mentioned lower limit, according to the composition of entirety, existence fully can not improve the corrosion resistance of the sintered body of manufacture and the possibility of mechanical performance, on the other hand, when the containing ratio of Mn exceedes above-mentioned higher limit, there is the possibility of corrosion resistance and mechanical performance reduction on the contrary.

Mo is the element of the corrosion resistance of the sintered body that strengthening manufactures.

In metal dust Mo containing ratio and be not particularly limited, be preferably below more than 1 quality % 5 quality %, be more preferably below more than 1.2 quality % 4 quality %, more preferably below more than 2 quality % 3 quality %.By being set in above-mentioned scope by the containing ratio of Mo, the density of the sintered body manufactured can not be caused significantly to reduce, and the corrosion resistance of more intensified-sintered body.

Cu is the element of the corrosion resistance of the sintered body that strengthening manufactures.

In metal dust Cu containing ratio and be not particularly limited, be preferably below 5 quality %, be more preferably below more than 1 quality % 4 quality %.By being set in above-mentioned scope by the containing ratio of Cu, the density of the sintered body manufactured can not be caused significantly to reduce, and the corrosion resistance of more intensified-sintered body.

N is the element of the mechanical performances such as the yield strength of the sintered body improving manufacture.

In metal dust N containing ratio and be not particularly limited, be preferably below more than 0.03 quality % 1 quality %, be more preferably below more than 0.08 quality % 0.3 quality %, more preferably below more than 0.1 quality % 0.25 quality %.By the containing ratio of N is set in above-mentioned scope, the significantly reduction of the density of the sintered body manufactured can not be caused, and more improve the mechanical performances such as the yield strength of sintered body.

In addition, when manufacture is added with the metal dust of N, use such as, use the method for the raw material after nitrogenize, to the method for motlten metal importing nitrogen, the method etc. to the metal dust applying nitrogen treatment manufactured.

S is the element of the cutting ability improving the sintered body manufactured.

In metal dust S containing ratio and be not particularly limited, be preferably below 0.5 quality %, be more preferably below more than 0.01 quality % 0.3 quality %.By the containing ratio of S is set in above-mentioned scope, the significantly reduction of the density of the sintered body manufactured can not be caused, and more improve the cutting ability of the sintered body of manufacture.

In addition, V, W, Co, B, Ti, Se, Te, Pd, Al etc. can be added in metal powder for powder metallurgy of the present invention.Now, the containing ratio of these elements is also not particularly limited, and is preferably less than 0.1 quality % respectively, is also preferably less than 0.2 quality % even if add up to.In addition, sometimes also inevitably containing these elements.

Further, impurity can be contained in metal powder for powder metallurgy of the present invention.The whole elements beyond above-mentioned Fe, Cr, Ni, Si, C, Zr, Nb, Mn, Mo, Cu, N, S, V, W, Co, B, Ti, Se, Te, Pd, Al can be enumerated as impurity, specifically, such as Li, Be, Na, Mg, P, K, Ca, Sc, Zn, Ga, Ge, Y, Ag, In, Sn, Sb, Hf, Ta, Os, Ir, Pt, Au, Bi etc. can be enumerated.It is fewer than each containing ratio of Fe, Cr, Ni, Si, C, Zr and Nb that the mixed volume of these impurity is preferably set to each element.In addition, the mixed volume of these impurity is preferably set to each element and is less than 0.03 quality %, is more preferably set smaller than 0.02 quality %.In addition, be also preferably less than 0.3 quality % even if add up to, be more preferably and be less than 0.2 quality %.In addition, these elements, if its containing ratio is in above-mentioned scope, then because effect described above is not interrupted, therefore can add consciously.

On the other hand, although O (oxygen) also can add consciously or inevitably be mixed into, its amount is preferably about below 0.8 quality %, is more preferably about below 0.5 quality %.By absorbing the oxygen amount so far degree in metal dust, thus agglutinating property uprises, and can obtain high density and the sintered body of mechanical performance excellence.In addition, although lower limit does not set especially, be preferably more than 0.03 quality % from the viewpoint of volume production easiness etc.

Fe is the composition (main component) that in the alloy forming metal powder for powder metallurgy of the present invention, containing ratio is the highest, makes a big impact to the characteristic of sintered body.The containing ratio of Fe is also not particularly limited, and is preferably more than 50 quality %.

In addition, the proportion of composing of metal powder for powder metallurgy, such as, the iron that can be specified by JIS G 1257 (2000) and copper-atomic absorption spectroscopy, the iron that JIS G 1258 (2007) specifies and copper-ICP emission spectrometry method, the iron that JIS G 1253 (2002) specifies and steel-spark discharge emission spectrometry method, the iron that JIS G 1256 (1997) specifies and steel-x ray fluorescence spectrometry, weight, titration, absorption photometry etc. that JIS G 1211 ~ G 1237 specifies are determined.Specifically, such as can enumerate solid emissive spectral analysis device (the spark discharge emission spectrographic analysis device that Spike company manufactures, model: SPECTROLAB, type: LAVMB08A), and the ICP device (CIROS120 type) that (Co., Ltd.) Rigaku manufactures.

In addition, JIS G 1211 ~ G 1237 is as described below.

JIS G 1211 (2011) iron and steel-carbon quantitative approach

JIS G 1212 (1997) iron and steel-silicon quantitative approach

Manganese quantitative approach in JIS G 1213 (2001) iron and steel

JIS G 1214 (1998) iron and steel-phosphorus quantitative approach

JIS G 1215 (2010) iron and steel-sulphur quantitative approach

JIS G 1216 (1997) iron and steel-nickel quantitative approach

JIS G 1217 (2005) iron and steel-chromium quantitative approach

JIS G 1218 (1999) iron and steel-molybdenum quantitative approach

JIS G 1219 (1997) iron and steel-copper quantitative approach

JIS G 1220 (1994) iron and steel-tungsten quantitative approach

JIS G 1221 (1998) iron and steel-vanadium quantitative approach

JIS G 1222 (1999) iron and steel-cobalt quantitative approach

JIS G 1223 (1997) iron and steel-titanium quantitative approach

Aluminium quantitative approach in JIS G 1224 (2001) iron and steel

JIS G 1225 (2006) iron and steel-arsenic quantitative approach

JIS G 1226 (1994) iron and steel-Xi quantitative approach

Boron quantitative approach in JIS G 1227 (1999) iron and steel

JIS G 1228 (2006) iron and steel-nitrogen quantitative approach

JIS G 1229 (1994) steel-plumbous quantitative approach

Zirconium quantitative approach in JIS G 1232 (1980) steel

JIS G 1233 (1994) steel-selenium quantitative approach

Tellurium quantitative approach in JIS G 1234 (1981) steel

Antimony quantitative approach in JIS G 1235 (1981) iron and steel

Tantalum quantitative approach in JIS G 1236 (1992) steel

JIS G 1237 (1997) iron and steel-niobium quantitative approach

In addition, when determining C (carbon) and S (sulphur), especially also use oxygen gas stream burning (high-frequency induction furnace the burning)-infrared absorption method that JIS G 1211 (2011) specifies.Specifically, carbon/Sulfur Analysis device CS-200 that LECO company manufactures can be enumerated.

And, when determining N (nitrogen) and O (oxygen), the nitrogen quantitative approach of the iron that special also use JIS G 1228 (2006) specifies and steel, the oxygen quantitative approach of the metal material that JIS Z 2613 (2006) specifies.Specifically, oxygen/nitrogen analysis device TC-300/EF-300 that LECO company manufactures can be enumerated.

In addition, metal powder for powder metallurgy of the present invention preferably has austenitic crystal structure.Austenitic crystal structure is given highly corrosion resistant to sintered body and is given high-elongation.Therefore, although there is the metal powder for powder metallurgy of this crystal structure for high density, the sintered body with highly corrosion resistant and high-elongation can also be manufactured.

In addition, whether metal powder for powder metallurgy has austenitic crystal structure, such as, can be judged by X-ray diffraction method.

In addition, the average grain diameter of metal powder for powder metallurgy of the present invention is preferably more than 0.5 μm less than 30 μm, is more preferably more than 1 μm less than 20 μm, more preferably more than 2 μm less than 10 μm.By using the metal powder for powder metallurgy of such particle diameter, because the emptying aperture remained in sintered body is few, so special high density can be manufactured and the sintered body of mechanical performance excellence.

In addition, average grain diameter is obtaining in the cumulative particle size distribution under quality criteria by laser diffractometry, particle diameter when to become 50% from path side as cumulant and trying to achieve.

In addition, when the average grain diameter of metal powder for powder metallurgy is lower than above-mentioned lower limit, when the shape being shaped difficult, there is formability to reduce, the possibility that sintered density reduces, when exceeding above-mentioned higher limit, during owing to being shaped, intergranular gap becomes large, eventually also there is the possibility that sintered density reduces.

In addition, the size distribution of metal powder for powder metallurgy is preferably as far as possible narrow.Specifically, if the average grain diameter of metal powder for powder metallurgy is in above-mentioned scope, then maximum particle diameter is preferably below 200 μm, is more preferably less than 150 μm.By controlling in above-mentioned scope by the maximum particle diameter of metal powder for powder metallurgy, the size distribution of metal powder for powder metallurgy can be made narrower, the more densification of sintered body can be realized.

In addition, above-mentioned maximum particle diameter refers in the cumulative particle size distribution under the quality criteria obtained by laser diffractometry, and cumulant becomes particle diameter when 99.9% from path side.

In addition, the minor axis of the particle of metal powder for powder metallurgy is set to S [μm], when major diameter is set to L [μm], is preferably about less than more than 0.4 1 with the mean value of the length-width ratio of S/L definition, is more preferably about less than more than 0.7 1.The metal powder for powder metallurgy of such length-width ratio is due to its shape matching subglobular, so filling rate when improving shaping.Its result, can realize the more densification of sintered body.

In addition, above-mentioned major diameter refers to the maximum length that can obtain in the projected image of particle, above-mentioned minor axis refer to the maximum length that can obtain on major diameter orthogonal direction.In addition, length-width ratio mean value as the value of the length-width ratio of mensuration more than 100 particles mean value and try to achieve.

In addition, the tap density of metal powder for powder metallurgy of the present invention is preferably 3.5g/cm ³above, 4g/cm is more preferably ³above.If the metal powder for powder metallurgy that tap density is large like this, then, when obtaining formed body, intergranular fillibility becomes high especially.Therefore, the sintered body of particularly compact can finally be obtained.

In addition, the specific area of metal powder for powder metallurgy of the present invention is also not particularly limited, and is preferably 0.1m ²/ more than g, is more preferably 0.2m ²/ more than g.If the metal powder for powder metallurgy that like this specific area is large, then because the activity (surface energy) on surface increases, even if so give less energy and also can easily sinter.Therefore, during sintered shaped body, be difficult to the difference of the inner and outer sintering velocity producing formed body, can suppress to remain emptying aperture in inner side and sintered density reduces.

The manufacture method of sintered body

Below, the method using such metal powder for powder metallurgy of the present invention to manufacture sintered body is described.

The method manufacturing sintered body has: A prepares the constituent preparation process of the constituent of sintered body manufacture; B manufactures the forming process of body; C applies the degreasing process of ungrease treatment; And D carries out the firing process that burns till.Below, successively each operation is described.

A constituent preparation process

First, prepare metal powder for powder metallurgy of the present invention and adhesive, by mixing roll, it is mixing, thus obtain mixing thing (constituent).

In this mixing thing (embodiment of compound of the present invention), powdered metal powder is dispersed.

Metal powder for powder metallurgy of the present invention, by such as, atomization (such as, water atomization, gas atomization, High Rotation Speed atomization of water current method etc.), the various powdered method such as reducing process, carbonyl process, comminuting method and manufacturing.

Wherein, metal powder for powder metallurgy of the present invention, preferably by atomization manufacture, is more preferably by water atomization or High Rotation Speed atomization of water current method and manufactures.Atomization is by making motlten metal (metallic solution) collide with the fluid (liquid or gas) of high velocity jet, making motlten metal powdered and cool, thus manufactures the method for metal dust.To be made powder metallurgy metal dust by such atomization, can effectively manufacture ultrafine powder thus.In addition, the grain shape of the powder obtained is subglobular due to capillary effect.Therefore, high fill-ratio can be obtained during shaping.That is, the powder that can manufacture highdensity sintered body can be obtained.

In addition, as atomization, when use water atomization time, to motlten metal injection water (below, become " atomized water ".) pressure and be not particularly limited, be preferably about more than 75MPa below 120MPa (750kgf/cm ²above 1200kgf/cm ²below), about more than 90MPa below 120MPa (900kgf/cm is more preferably ²above 1200kgf/cm ²below).

In addition, the water temperature of atomized water is also not particularly limited, and is preferably about more than 1 DEG C less than 20 DEG C.

Further, atomized water has summit in the descent path of motlten metal, is many with the situation of coniform injection decrescence below outer radial.Now, the vertex angle theta of the circular cone that atomized water is formed is preferably about more than 10 ° less than 40 °, is more preferably about more than 15 ° less than 35 °.Thereby, it is possible to reliably manufacture the metal powder for powder metallurgy of composition as above.

In addition, according to water atomization (particularly High Rotation Speed atomization of water current method), can quick especially cooling molten metal.Therefore, the powder of high-quality can be obtained in the composition of alloy widely.

In addition, the cooling velocity in atomization during cooling molten metal is preferably 1 × 10 ⁴dEG C/more than s, be more preferably 1 × 10 ⁵dEG C/more than s.Cooled fast by this, the metal powder for powder metallurgy of homogeneous can be obtained.Its result can obtain the sintered body of high-quality.

In addition, as required, classification can be carried out to the metal powder for powder metallurgy so obtained.As the method for classification, such as, can enumerate the wet classification etc. of the dry classification of sieving and grading, inertial classification, centrifugal classification and so on, classification of sedimentation and so on.

On the other hand, as adhesive, such as polyethylene can be enumerated, polypropylene, the polyolefin such as vinyl-vinyl acetate copolymer, polymethyl methacrylate, the acrylic resins such as polybutyl methacrylate, the styrene resins such as polystyrene, polyvinyl chloride, Vingon, polyamide, PETG, the polyester such as polybutylene terephthalate (PBT), polyethers, polyvinyl alcohol, the various resins such as polyvinylpyrrolidone or these copolymer, various wax, paraffin, higher fatty acids (such as stearic acid), higher alcohol, high-grade aliphatic ester, the various organic bond such as higher fatty acid amides, and can one or more in these used in combination.

In addition, the containing ratio of adhesive is preferably below more than the 2 quality % 20 quality % of about mixing thing entirety, is more preferably about below more than 5 quality % 10 quality %.By the containing ratio of adhesive in above-mentioned scope, can the good formed body of forming shaped, and can density be improved, the stability of the shape of formed body etc. can be made excellent especially.In addition, thereby, it is possible to make large difference, the so-called shrinkage factor optimization of formed body and degreasing body, prevent the dimensional accuracy of the sintered body finally obtained from reducing.That is, high density can be obtained and the high sintered body of dimensional accuracy.

In addition, in mixing thing, as required, plasticizer can be added.Such as can enumerate phthalic acid ester (such as: DOP, DEP, DBP), adipate ester, trimellitate, sebacate etc. as this plasticizer, can one or more in these be carried out used in combination.

And, in mixing thing, except metal powder for powder metallurgy, adhesive, plasticizer, as required, such as, can add the various additives such as lubricant, antioxidant, degreasing promoter, surfactant.

In addition, compounding conditions is different along with all many condition differences such as the composition of the metal composition of metal powder for powder metallurgy used, particle diameter, adhesive and these allotment amounts, enumerate a wherein example, melting temperature can be set to about more than 50 DEG C less than 200 DEG C, and mixing time can be set to about more than 15 points less than 210 points.

In addition, as required, carry out particle (fritter) to mixing thing to change.The particle diameter of particle is such as approximately more than 1mm below 15mm.

In addition, according to manufacturing process described later, replace mixing thing, can prilling powder be manufactured.These mixing thing and prilling powder etc. are available to an example of the constituent of aftermentioned forming process.

The embodiment of prilling powder of the present invention is by applying granulation process to metal powder for powder metallurgy of the present invention, utilizing adhesive to be bonded to one another by multiple metallic particles and form.

As the adhesive of the manufacture for prilling powder, such as polyethylene can be enumerated, polypropylene, the polyolefin such as vinyl-vinyl acetate copolymer, polymethyl methacrylate, the acrylic resins such as polybutyl methacrylate, the styrene resins such as polystyrene, polyvinyl chloride, Vingon, polyamide, PETG, the polyester such as polybutylene terephthalate (PBT), polyethers, polyvinyl alcohol, the various resins such as polyvinylpyrrolidone or these copolymers, various wax, paraffin, higher fatty acids (such as stearic acid), higher alcohol, high-grade aliphatic ester, the various organic bond such as higher fatty acid amides, and can one or more in these used in combination.

Wherein, preferably polyvinyl alcohol or polyvinylpyrrolidone is contained as adhesive.These adhesive ingredients due to caking property high, even if small amount also can form prilling powder expeditiously.In addition, because pyrolytic is also high, so degreasing and when burning till, can reliably decompose in the short time, remove.

In addition, the containing ratio of adhesive is preferably below more than the 0.2 quality % 10 quality % of about prilling powder entirety, is more preferably about below more than 0.3 quality % 5 quality %, more preferably 0.3 below quality %2 quality %.By the containing ratio of adhesive in above-mentioned scope, can the very large particle of granulation, suppress do not have the metallic particles of granulation remaining in a large number, and effectively can form prilling powder.In addition, because formability improves, the stability of the shape of formed body etc. can be made excellent especially.In addition, by making the containing ratio of adhesive in above-mentioned scope, the difference between the size of formed body and degreasing body, so-called shrinkage factor optimization can be made, the reduction of the dimensional accuracy of the sintered body finally obtained can be prevented.

Further, in prilling powder, according to required, the various additives such as plasticizer, lubricant, antioxidant, degreasing promoter, surfactant can be added.

On the other hand, as granulation process, such as, can enumerate spray drying process, rotary granulation, fluidized bed comminution granulation, rotational flow comminution granulation etc.

In addition, in granulation process, as required, the solvent dissolving adhesive is used.Such solvent comprises, such as can enumerate the organic solvent etc. of the inorganic solvent of water, carbon tetrachloride and so on, ketone solvent, alcoholic solvent, ether solvents, cellosolve type solvents, Aliphatic hydrocarbon solvents, aromatic hydrocarbon solvent, aromatic heterocyclic compounds kind solvent, amide solvent, halogen compounds kind solvent, ester solvent, amine solvent, nitrile solvent, nitro kind solvent, acetaldehyde kind solvent and so on, and one or more the mixture selected from these can be used.

The average grain diameter of prilling powder is also not particularly limited, and is preferably about more than 10 μm less than 200 μm, is more preferably about more than 20 μm less than 100 μm, more preferably about more than 25 μm less than 60 μm.The prilling powder of such particle diameter has good mobility, and more verily can reflect the shape of shaping dies.

In addition, in the cumulative particle size distribution of average grain diameter under the quality criteria obtained according to laser diffractometry, particle diameter when to become 50% from path side as cumulant and trying to achieve.

B forming process

Below, mixing thing or prilling powder are shaped, manufacture the formed body with target sintered body same shape.

As formed body manufacture method (manufacturing process) and be not particularly limited, such as can use press-powder be shaped (compression molding) method, metal powder injection molded (MIM:Metal Injection Molding) various forming process such as method, extrusion molding method.

Wherein, molding condition during press-powder forming process along with all many condition of the composition of the composition of metal powder for powder metallurgy used, particle diameter, adhesive and these allotment amount etc. different and different, forming pressure is preferably more than 200MPa below 1000Mpa (2t/cm ²above 10t/cm ²degree below).

In addition, although molding condition during metal powder injection molded method is different along with all many condition, material temperature is preferably about more than 80 DEG C less than 210 DEG C, and injection pressure is preferably about more than 50MPa below 500MPa (0.5t/cm ²above 5t/cm ²below).

In addition, although molding condition during extrusion molding method is different along with all many condition, material temperature is preferably approximately more than 80 DEG C less than 210 DEG C, and extrusion pressure is preferably approximately more than 50MPa below 500MPa (0.5t/cm ²above 5t/cm ²below).

The formed body obtained thus is formed in the equally distributed state of adhesive in the gap of multiple particles of metal dust.

In addition, the geomery of the formed body of making passes through the shrinkage factor of the degreasing process after expectation and the formed body in firing process and determines.

C degreasing process

Below, ungrease treatment (process of unsticking mixture) is applied to the formed body obtained, obtains degreasing body.

Specifically, by being heated into body, adhesive being decomposed, from formed body, removes adhesive, completing ungrease treatment.

This ungrease treatment such as can enumerate be heated into body method, formed body is exposed to adhesive is decomposed gas in method etc.

When use is heated into the method for body, although the heating condition of formed body along with the composition of adhesive different and slightly different with allotment amount, but be preferably approximately temperature more than 100 DEG C less than 750 DEG C × more than 0.1 hour less than 20 hours, be more preferably more than 150 DEG C less than 600 DEG C × more than 0.5 hour less than 15 hours.Thereby, it is possible to necessary and form the degreasing of body fully and do not make formed body sinter.Its result, can reliably prevent adhesive ingredients from remaining in the inside of degreasing body in a large number.

In addition, gas atmosphere when being heated into body is also not particularly limited, and can enumerate the reducibility gas atmosphere of hydrogen and so on, the inert gas atmosphere of nitrogen, argon gas and so on, the oxidizing gas atmosphere of air and so on, or by the depressed gas atmosphere etc. after these gas decompression.

On the other hand, such as ozone gas etc. can be enumerated as the gas making adhesive decompose.

In addition, this degreasing process by separately carrying out the different multiple processes (step) of degreasing condition, can more fast and do not remain in formed body decompose, adhesive in Material removal body.

In addition, as required, the machinings such as cutting, grinding, cut-out can be applied to degreasing body.Degreasing body due to hardness ratio lower, and plasticity is comparatively large, therefore, it is possible to prevent the shape of degreasing body to be out of shape, and easily can apply machining.By this machining, finally the high sintered body of dimensional accuracy easily can be obtained.

D firing process

The degreasing body obtained in above-mentioned operation C is being burnt till kiln roasting thus obtaining sintered body.

By this sintering, metal powder for powder metallurgy spreads at particle interface each other, completes sintering.Now, by mechanism as above, degreasing body is by Fast Sintering.Its result, can obtain the highdensity sintered body of overall densification.

Although firing temperature is different from the composition and particle diameter etc. of the metal powder for powder metallurgy of the manufacture for formed body and degreasing body, is about more than 980 DEG C less than 1330 DEG C as an example.In addition, be preferably approximately more than 1050 DEG C less than 1260 DEG C.

In addition, firing time is more than 0.2 hour less than 7 hours, is preferably about more than 1 hour less than 6 hours.

In addition, in firing process, firing temperature can be changed halfway and described laterly burn till gas atmosphere.

By firing condition being set in this scope, can either preventing sintering from excessively becoming excess agglomeration, crystalline structure expands, the overall fully sintering of degreasing body can be made again.Its result, can obtain high density and the excellent especially sintered body of mechanical performance.

In addition, because firing temperature is lower, so be easily certain by heating and temperature control by firing furnace, therefore, the temperature of degreasing body is also easily certain.Its result, can manufacture the sintered body of more homogeneous.

Further, firing temperature as above, owing to being the firing temperature that can fully be realized by general firing furnace, so can use cheap firing furnace, also can suppress operating cost.In other words, when exceeding above-mentioned firing temperature, needing to utilize and use the high price firing furnace of special heat proof material, and there is the possibility that operating cost uprises.

In addition, although gas atmosphere when burning till also is not particularly limited, when considering to prevent the remarkable oxidation of metal dust, preferably use this reducibility gas atmosphere of hydrogen, this inert gas atmosphere of argon gas, or by post-decompression for these gas atmospheres depressed gas atmosphere etc.

The sintered body so obtained becomes high density and the sintered body of mechanical performance excellence.That is, after being shaped by the constituent containing metal powder for powder metallurgy of the present invention and adhesive, the sintered body manufactured after carrying out degreasing, sintering is compared with the sintered body of the existing metal dust of sintering, and relative density increases.Therefore, if the present invention, then can not apply this additional treatments of HIP process, if realize not applying additional treatments, be beyond one's reach highdensity sintered body.

Specifically, according to the present invention, although slightly different due to the composition of metal powder for powder metallurgy, the raising of the relative density of more than 2% compared with prior art can be expected as an example.

Its result, the relative density of the sintered body obtained can be expected to reach more than 97% (be preferably more than 98%, be more preferably more than 98.5%) as an example.There is the sintered body of the relative density of this scope, although have the shape of infinite approach target shape by utilizing PM technique, but due to the mechanical performance of the excellence with the ingot that is equal to, so can aft-loaded airfoil be applied hardly and be applicable to various mechanical part and structural member.

In addition, after constituent containing metal powder for powder metallurgy of the present invention and binding is shaped, the sintered body manufactured after carrying out degreasing, sintering, the tensile strength of the sintered body that its tensile strength and 0.2% yield strength ratio use existing metal dust similarly to sinter and 0.2% yield strength increase.Can think, this is because by alloy is formed optimization, thus improve the agglutinating property of metal dust, the mechanical performance of the sintered body manufactured thus improves.

In addition, the surface of the sintered body manufactured as mentioned above is high rigidity.Specifically, although slightly different along with the composition difference of metal powder for powder metallurgy, expect that as an example Vickers hardness on surface is less than more than 140 500.In addition, expect to be preferably less than more than 150 400.The sintered body with such hardness has extra high durability.

In addition, even if do not apply additional treatments, sintered body also has enough high density and mechanical performance, but in order to realize more densification and improve mechanical performance, also can apply various additional treatments.

As this additional treatments, can be such as the such additional treatments realizing densification of above-mentioned HIP process, also can be various Quenching Treatment, various subzero treatment, various temper etc.These additional treatments can be carried out separately, also can multiple combination carry out.

In addition, in above-mentioned firing process and various additional treatments, in metal dust, the light element of (in sintered body) plays, and the composition of the sintered body finally obtained changes a little from the composition metal dust sometimes.

Such as, although about C along with process conditions is different with treatment conditions and different, the possibility that the containing ratio in final sintered body exists in the scope of less than more than 5% 100% of containing ratio in metal powder for powder metallurgy the scope of less than more than 30% 100% (preferably in) changes.

In addition, O too, although along with process conditions is different with treatment conditions and different, the possibility that in the scope that the containing ratio in final sintered body exists less than more than 1% 50% of containing ratio in metal powder for powder metallurgy, (being preferably in the scope of less than more than 3% 50%) changes.

On the other hand, as mentioned above, the sintered body manufactured can carry out HIP process at a ring of the additional treatments of carrying out as required, even if but sometimes carry out HIP process, can not effect be given full play to.Although HIP process can realize the more densification of sintered body, obtain sintered body in initial the present invention and realized sufficient densification at the end of firing process.Therefore, even if implement HIP process further, be also difficult to carry out further densification.

In addition, in HIP process, because needs to be pressurizeed treated object by pressure medium, therefore there is treated object contaminated, along with the change of polluting the composition that produces treated object and not expecting with physical property, and along with the possibility of pollution treated object variable color.In addition, also there is following possibility: due to pressurized and produce in treated object or increase residual stress, cause along with these residual stress along with the time is released, and produce distortion or accuracy to size reduces such problem.

To this, according to the present invention, manufacture the high sintered body of abundant density due to such HIP process can not be applied, thus can be accomplished the sintered body of the densification identical with when implementing HIP process and high strength.Further, such sintered body pollution, variable color, the change of composition transitivity do not expected etc. are few, and the generation that distortion and dimensional accuracy reduce this problem is also lacked.Therefore, according to the present invention, can effectively manufacturing machine intensity and accuracy to size high, the sintered body of excellent in te pins of durability.

In addition, the sintered body produced in the present invention is owing to almost there is no need the additional treatments of carrying out for improving mechanical performance, so composition and crystalline structure easily become even in whole sintered body.Therefore, structure isotropism is high, and how shape is for all excellent from the directive load durability of institute.

Confirm in addition, in the sintered body produced like this, the situation that the void content of its near surface diminishes relatively than internal voids rate is many.Although occur that the reason of this situation is indefinite, can list owing to adding Zr and Nb, compared with the inside of formed body, more easily carry out near surface sintering reaction.

Specifically, the void content of the near surface of sintered body is set to A1, when the void content of the inside of sintered body is set to A2, A2-A1 is preferably less than more than 0.5% 10%, is more preferably less than more than 1% 5%.A2-A1 has necessity and sufficient mechanical strength at the sintered body of this scope, on the other hand, surface can be made easily planarized.That is, by grinding the surface of this sintered body, the surface that specularity is high can be obtained.

The high sintered body of such specularity not only mechanical strength uprises, and has excellent aesthetic feeling.Therefore, this sintered body is also applicable to the purposes requiring aesthetic look.

In addition, the void content A1 of the near surface of sintered body refers in the cross section of sintered body, by distance surface 50 μm the degree of depth position centered by radius 25 μm scope in void content.In addition, the void content A2 of the inside of sintered body refers in the cross section of sintered body, by distance surface 300 μm the degree of depth position centered by radius 25 μm scope in void content.These void contents are the cross sections being observed sintered body by scanning electron microscope, and the area of the emptying aperture existed in above-mentioned scope removes rear obtained value with the area of above-mentioned scope.

Above, based on metal powder for powder metallurgy of the present invention, compound, prilling powder and sintered body, although based on being preferred embodiment illustrated, the present invention is not limited to this.

In addition, sintered body of the present invention is used for such as automobile component, bicycle assembly parts, rolling stock parts, ship components, aircraft components, the conveying equipment parts of universe transporter (such as robot etc.) parts and so on, machine element, the electronic equipment part of mobile telephone terminal parts and so on, refrigerator, washing machine, the electrical equipment component of air-conditioning and so on, work mechanism, the mechanical part of semiconductor-fabricating device and so on, nuclear power plant, steam power plant, hydraulic power plant, oil plant, the shop equipment parts of chemical combined enterprise and so on, watch parts, metalic tableware, Jewelry Accessories, the structural member that ornament of spectacle frame and so on etc. is all.

Embodiment

Below, embodiments of the invention are described.

1. the manufacture of sintered body

(sample No.1)

1, first, the metal dust of the composition shown in table 1 produced by water atomization is prepared.In addition, the average grain diameter of this metal dust is 4.05 μm, and tap density is 4.20g/cm ³, specific area is 0.23m ²/ g.

In addition, the composition of the powder shown in table 1 has carried out qualification, quantitatively by ICP-AES (ICP method).In addition, in icp analysis, employ the ICP device (CIROS120 type) that (Co., Ltd.) Rigaku manufactures.In addition, C qualification, quantitatively employ LECO company manufacture carbon/Sulfur Analysis device (CS-200).And, the qualification of O, quantitatively employ oxygen/nitrogen analysis device (TC-300/EF-300) that LECO company manufactures.

2, secondly, the mixture (organic bond) of metal dust and polypropylene and wax is weighed to mix reach mass ratio 9: 1, obtain mixed material.

3, then, this mixed material is carried out mixing in mixing roll, thus obtains compound.

4, secondly, by this compound according to the molding condition illustrated below, be shaped at injection machine, produce formed body.

Molding condition

Material temperature: 150 DEG C

Injection pressure: 11MPa (110kgf/cm ²)

5, secondly, to the formed body obtained, apply heat treatment (ungrease treatment) according to the degreasing condition illustrated below, obtain degreasing body.

Degreasing condition

Skimming temp: 500 DEG C

Degreasing time: 1 hour (retention time under skimming temp)

Degreasing gas atmosphere: nitrogen atmosphere

6, secondly, degreasing body will be obtained, burn till according to the firing condition illustrated below.Thus, sintered body is obtained.In addition, the shape of sintered body is the drum of diameter 10mm, thickness 5mm.

Firing condition

Firing temperature: 1150 DEG C

Firing time: 3 hours (retention time under firing temperature)

Burn till gas atmosphere: argon gas atmosphere

(sample No.2 ~ 30)

Except the composition etc. of change metal powder for powder metallurgy as shown in table 1, all the other obtain sintered body respectively identically with the manufacture method of the sintered body of sample No.1.In addition, for the sintered body of sample No.30, after burning till, be applied with HIP process under the following conditions.In addition, the sintered body of sample No.18 ~ 20 is used the metal dust that manufactured by gas atomization respectively and obtains.In addition, be marked as " gas " in the remarks column of table 1.

HIP treatment conditions

Heating-up temperature: 1100 DEG C

Heat time: 2 hours

Plus-pressure: 100MPa

Table 1

In addition, in Table 1, in the sintered body of each sample No., being equivalent to of the present invention is " embodiment ", and not being equivalent to of the present invention is " comparative example ".

In addition, although comprise the impurity of trace at each sintered body, record is omitted in Table 1.

(sample No.31 ~ 48)

Except the composition etc. of change metal powder for powder metallurgy as shown in table 2, all the other obtain sintered body respectively identically with the manufacture method of the sintered body of sample No.1.In addition, for the sintered body of sample No.48, after burning till, be applied with HIP process under the following conditions.In addition, the sintered body of sample No.41 ~ 43 is used the metal dust that manufactured by gas atomization respectively and obtains.In addition, be marked as " gas " in the remarks column of table 2.

HIP treatment conditions

Heating-up temperature: 1100 DEG C

Heat time: 2 hours

Plus-pressure: 100MPa

Table 2

In addition, in table 2, in the sintered body of each sample No., being equivalent to of the present invention is " embodiment ", and not being equivalent to of the present invention is " comparative example ".

In addition, although the impurity of each sintered body containing trace, record is omitted in table 2.

(sample No.49 ~ 66)

Except the composition etc. of change metal powder for powder metallurgy as shown in table 3, all the other obtain sintered body respectively identically with the manufacture method of the sintered body of sample No.1.In addition, for the sintered body of sample No.66, after burning till, under following condition, be applied with HIP process.In addition, the sintered body of sample No.59 ~ 61 is used the metal dust that manufactured by gas atomization respectively and obtains.In addition, be marked as " gas " in the remarks column of table 3.

HIP treatment conditions

Heating-up temperature: 1100 DEG C

Heat time: 2 hours

Plus-pressure: 100MPa

Table 3

In addition, in table 3, in the sintered body of each sample No., being equivalent to of the present invention is " embodiment ", and not being equivalent to of the present invention is " comparative example ".

In addition, although the impurity of each sintered body containing trace, omit in table 3 and record.

(sample No.67)

1, first, identically with the situation of sample No.1, the metal dust of composition as shown in table 4 is produced by water atomization.

2, secondly, by spray drying process, granulation is carried out to metal dust.The adhesive now used is polyvinyl alcohol, and employing relative to metal dust 100 Quality Mgmt Dept is the amount of 1 Quality Mgmt Dept.In addition, the solvent (ion exchange water) of 50 Quality Mgmt Dept is employed relative to polyvinyl alcohol 1 Quality Mgmt Dept.Thus, the prilling powder of average grain diameter 50 μm is obtained.

3, then, this prilling powder press-powder under molding condition as follows is shaped.In addition, this shaping employs Press forming machine.In addition, the shape of the formed body of manufacture is the square cubic shaped of 20mm.

Molding condition

Material temperature: 90 DEG C

Forming pressure: 600MPa (6t/cm ²)

4, secondly, for the formed body obtained, under degreasing condition as follows, apply heat treatment (ungrease treatment), obtain degreasing body.

Degreasing condition

Skimming temp: 450 DEG C

Degreasing time: 2 hours (retention time under skimming temp)

Degreasing gas atmosphere: nitrogen atmosphere

5, secondly, the degreasing body obtained is burnt till under firing condition as follows.Thus, sintered body is obtained.

Firing condition

Firing temperature: 1150 DEG C

Firing time: 3 hours (retention time under firing temperature)

Burn till gas atmosphere: argon gas atmosphere

(sample No.68 ~ 87)

Except the composition etc. of change metal powder for powder metallurgy as shown in table 4, all the other obtain sintered body respectively identically with during sample No.67.In addition, to the sintered body of sample No.87, after burning till, implement HIP process according to following condition.

HIP treatment conditions

Heating-up temperature: 1100 DEG C

Heat time: 2 hours

Plus-pressure: 100MPa

Table 4

In addition, in table 4, in the metal powder for powder metallurgy of each sample No. and sintered body, being equivalent to of the present invention is " embodiment ", and not being equivalent to of the present invention is " comparative example ".

2. the evaluation of sintered body

The evaluation of 2.1 relative densities

With the method for the density of the mensuration sintered metal materials specified at JIS Z 2501 (2000) for benchmark, sintered density is determined to the sintered body of each sample No., and with reference to manufacturing the real density of the metal powder for powder metallurgy that each sintered body uses, calculate the relative density of each sintered body.

Measurement result is illustrated in table 5 ~ 8.

The evaluation of 2.2 dimension hardness

The test method of the dimension hardness test specified with JIS Z 2244 (2009), for benchmark, determines dimension hardness to the sintered body of each sample No..

The evaluation of 2.3 tensile strength, 0.2% yield strength and percentage elongation

The Tensile Testing Method of Metallic Materials specified with JIS Z 2241 (2011), for benchmark, determines tensile strength to the sintered body of each sample No., 0.2% yield strength and percentage elongation.

Further, according to following evaluation criterion, these physics values measured are evaluated.

The evaluation criterion (table 5,8) of tensile strength

A: the tensile strength of sintered body is more than 520MPa

B: the tensile strength of sintered body is that more than 510MPa is less than 520MPa

C: the tensile strength of sintered body is that more than 500MPa is less than 510MPa

D: the tensile strength of sintered body is that more than 490MPa is less than 500MPa

E: the tensile strength of sintered body is that more than 480MPa is less than 490MPa

F: the tensile strength of sintered body is less than 480MPa

The evaluation criterion (table 6,7) of tensile strength

A: the hot strength of sintered body is more than 560MPa

B: the tensile strength of sintered body is that more than 550MPa is less than 560MPa

C: the tensile strength of sintered body is that more than 540MPa is less than 550MPa

D: the tensile strength of sintered body is that more than 530MPa is less than 540MPa

E: the tensile strength of sintered body is that more than 520MPa is less than 530MPa

F: the tensile strength of sintered body is less than 520MPa

The evaluation criterion (table 5,8) of 0.2% yield strength

A: 0.2% yield strength of sintered body is more than 195MPa

B: 0.2% yield strength of sintered body is that more than 190MPa is less than 195MPa

C: 0.2% yield strength of sintered body is that more than 185MPa is less than 190MPa

D: 0.2% yield strength of sintered body is that more than 180MPa is less than 185MPa

E: 0.2% yield strength of sintered body is that more than 175MPa is less than 180MPa

F: 0.2% yield strength of sintered body is less than 175MPa

The evaluation criterion (table 6,7) of 0.2% yield strength

A: 0.2% yield strength of sintered body is more than 225MPa

B: 0.2% yield strength of sintered body is that more than 220MPa is less than 225MPa

C: 0.2% yield strength of sintered body is that more than 215MPa is less than 220MPa

D: 0.2% yield strength of sintered body is that more than 210MPa is less than 215MPa

E: 0.2% yield strength of sintered body is that more than 205MPa is less than 210MPa

F: 0.2% yield strength of sintered body is less than 205MPa

The evaluation criterion of percentage elongation

A: the percentage elongation of sintered body is more than 48%

B: the percentage elongation of sintered body is more than 46% be less than 48%

C: the percentage elongation of sintered body is more than 44% be less than 46%

D: the percentage elongation of sintered body is more than 42% be less than 44%

E: the percentage elongation of sintered body is more than 40% be less than 42%

F: the percentage elongation of sintered body is for being less than 40%

Above evaluation result is shown in table 5 ~ 8.In addition, as mentioned above, different according to physics value, table 5,8 different from metewand in table 6,7.

Table 5

Table 6

Table 7

Table 8

From table 5 ~ 8 clearly, the sintered body being equivalent to embodiment and the sintered body being equivalent to comparative example are (except being applied with the sintered body of HIP process.) compare, relative density and dimension hardness high.In addition, also confirm that tensile strength, 0.2% yield strength and these characteristics of percentage elongation exist significant difference.

On the other hand, being equivalent to the sintered body of embodiment with after physics value more each between the sintered body being applied with HIP process, can confirm it is all equal extent.

The cross-section of 2.4 sintered bodies undertaken by scanning electron microscope (SEM)

To the cross section of sintered body being equivalent to embodiment, obtain observation image by scanning electron microscope (NEC manufactures, JXA-8500F).In addition, accelerating potential during shooting is 15kV, and enlargement ratio is 10,000 times.

The result of observing, on the cross section of each sintered body, in dark graininess region (first area) on observation image, and is positioned at the position of encirclement first area and is identified in light region (second area).Therefore, the mean value of the diameter of equivalent circle of the first area of trying to achieve, is all approximately more than 2 μm less than 8 μm in any sintered body.

Then, the qualitative and quantitative analysis of viewing area is carried out by electron beam microscopic analyzer.Its result, in first area, between the containing ratio of Si and the containing ratio sum of O are 2.5 times to 3.5 times of the containing ratio of Fe.In addition, in first area, the containing ratio of Si is more than 14 times of the containing ratio of Si in second area.In addition, in first area, the containing ratio of Zr is more than 3 times of the containing ratio of Zr in second area.

Can be confirmed by above-mentioned situation, in the sintered body being equivalent to embodiment, silica accumulates for core with Zr carbide etc.

Can confirm thus, according to the present invention, even if do not apply the additional treatments realizing densification of HIP process and so on, also can give the high density identical with the sintered body being applied with HIP process and excellent mechanical performance to sintered body.

In addition, can confirm after carrying out crystal structure analysis according to X-ray diffraction, the sintered body being equivalent to embodiment all has based on the structure of austenitic crystal structure.

Claims

1. a metal powder for powder metallurgy, is characterized in that,

Fe is main component;

Cr containing the following ratio of more than 15 quality % 26 quality %;

Ni containing the following ratio of more than 7 quality % 22 quality %;

Si containing the following ratio of more than 0.3 quality % 1.2 quality %;

C containing the following ratio of more than 0.005 quality % 0.3 quality %;

Zr containing the following ratio of more than 0.01 quality % 0.5 quality %; And

Nb containing the following ratio of more than 0.01 quality % 0.5 quality %.

2. metal powder for powder metallurgy according to claim 1, is characterized in that,

There is austenitic crystal structure.

3. metal powder for powder metallurgy according to claim 1 and 2, is characterized in that,

The containing ratio of Zr is less than more than 0.3 3 relative to the ratio Zr/Nb of the containing ratio of Nb.

4. metal powder for powder metallurgy according to any one of claim 1 to 3, is characterized in that,

The containing ratio of Zr and the containing ratio of Nb add up to below more than 0.05 quality % 0.6 quality %.

5. metal powder for powder metallurgy according to any one of claim 1 to 4, is characterized in that,

Mo also containing the following ratio of more than 1 quality % 5 quality %.

6. metal powder for powder metallurgy according to any one of claim 1 to 5, is characterized in that,

The average grain diameter of described metal powder for powder metallurgy is more than 0.5 μm less than 30 μm.

7. a compound, is characterized in that, contains:

Metal powder for powder metallurgy according to any one of claim 1 to 6; And

Adhesive, is bonded to each other the particle of described metal powder for powder metallurgy.

8. a prilling powder, is characterized in that,

Carry out granulation by the metal powder for powder metallurgy according to any one of claim 1 to 6 and formed.

9. a sintered body, is characterized in that,

Obtained by sinter powder metal metal dust,

In described metal powder for powder metallurgy,

Fe is main component;

Cr containing the following ratio of more than 15 quality % 26 quality %;

Ni containing the following ratio of more than 7 quality % 22 quality %;

Si containing the following ratio of more than 0.3 quality % 1.2 quality %;

C containing the following ratio of more than 0.005 quality % 0.3 quality %;

Nb containing the following ratio of more than 0.01 quality % 0.5 quality %.

10. sintered body according to claim 9, is characterized in that, comprising:

First area, in graininess and the containing ratio of silica is relatively high; And

Second area, the containing ratio of silica is relatively low compared with described first area.