CN109112262A - High-strength spring rolled stock and the high-strength spring silk material for having used it - Google Patents

High-strength spring rolled stock and the high-strength spring silk material for having used it Download PDF

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Publication number
CN109112262A
CN109112262A CN201811092603.3A CN201811092603A CN109112262A CN 109112262 A CN109112262 A CN 109112262A CN 201811092603 A CN201811092603 A CN 201811092603A CN 109112262 A CN109112262 A CN 109112262A
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amount
rolled stock
strength spring
hydrogen
silk material
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竹田敦彦
增田智
增田智一
高山将
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Kobe Steel Ltd
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Kobe Steel Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
    • B21C1/003—Drawing materials of special alloys so far as the composition of the alloy requires or permits special drawing methods or sequences
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C21D3/06—Extraction of hydrogen
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    • C21—METALLURGY OF IRON
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
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    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2261/00—Machining or cutting being involved

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Abstract

Present invention aims at still have excellent wire-drawing workability, and the high-strength spring rolled stock of excellent corrosion fatigue characteristic can be played after Q-tempering even if providing a kind of additive amount for inhibiting alloying element.The present invention is a kind of high-strength spring rolled stock, it is characterized in that, contain C, Si, Mn, P, S, Al, Cu, Ni, non-diffusing hydrogen amount is 0.40 mass ppm or less, ferritic the area ratio expressed as a percentage meets following (1) formulas, and total the area ratio of bainite and martensite is below 2%.× 100 ... (1) are wherein by ferrite the area ratio < { (0.77- [C])/0.77- [C]/3+0.08 }, in above-mentioned (1) formula, [masurium] means each element with the content of quality % table.

Description

High-strength spring rolled stock and the high-strength spring silk material for having used it
The application is application number: 201480070614.5, the applying date: 2014.12.10, denomination of invention: " high-strength spring With rolled stock and the high-strength spring silk material for having used it " PCT/JP2014/082728 application divisional application.
Technical field
The present invention relates to high-strength spring rolled stock and the high-strength spring silk materials for having used it.In detail, it is As in quenched, i.e., the useful rolled stock of the former material of the high-strength spring used in the state of Q-tempering and silk material, especially Even if be related to excellent in wire-drawing workability rolled stock and silk material processing after tensile strength be 1900MPa or more high intensity, Corrosion fatigue characteristic also excellent high-strength spring silk material.
Background technique
For helical spring of automobile etc., such as valve spring used in engine and suspension etc., bearing spring etc., in order to The reduction of exhaust gas and fuel efficiency improve and are required lightweight, and require high intensity.In the manufacture of high-intensitive silk material, Before the heat treatment of Q-tempering, implemented for the purpose of improving the dimensional accuracy of line footpath, making microstructure homogenization by plastic processing Wire drawing.Especially in high-intensitive silk material, change tissue more evenly for hair and increase the working modulus of wire drawing, rolled stock needs There is good wire-drawing workability.In addition, the spring lacking toughness ductility of high intensity, is easy to happen hydrogen brittleness, corrosion fatigue Characteristic reduces.Therefore, require corrosion fatigue characteristic excellent the steel wire for high-strength spring (silk material) of the manufacture for spring.It is rotten Losing fatigue fracture is caused as the hydrogen caused by steel embrittlement generation, so being in the hydrogen intrusion steel occurred because of corrosion Improvement corrosion fatigue characteristic, needs to be improved the corrosion resistance and resistance to hydrogen embrittlement of steel.
The raising of the corrosion fatigue characteristic of stringiness and high-strength spring silk material as high-strength spring rolled stock Method, it is known that be controlled by chemical composition.But in these methods, because largely using alloying element, It may not be ideal from the viewpoint of the increase of manufacturing cost and economizing on resources.
So, as the manufacturing method of spring, it is known to steel wire are heated to hardening heat and be thermoformed into spring shape The method of oily cold tempering again afterwards, and carry out after Q-tempering that cold forming is the method for spring shape again for steel wire.In addition rear In the cold forming method of person, it is also known that the Q-tempering before being formed by high-frequency heating, such as in patent document 1, it is public It is provided with a kind of in the skill for adjusting tissue to wire rod progress cold drawing and then by high-frequency induction heating progress Q-tempering Art.In the art, by making the tissue point rate 30% of pearlite hereinafter, the tissue for constituting martensite and bainite point Rate is 70% or more, carries out cold drawing thereafter with defined sectional shrinkage, Q-tempering is then carried out, to make undissolved carbon Compound is reduced, and improves delayed fracture characteristic.
In patent document 2, wire drawing is carried out for rolled wire in embodiment, is carried out at Q-tempering through high-frequency heating Reason.In the art, the starting point is placed on and is taken into account on high-intensitive and formability (windability), it is not any for resistance to hydrogen embrittlement Consider.
In patent document 3, hydrogen in the steel that the total hydrogen amount released when being conceived to according to from room temperature to 350 DEG C is evaluated Amount proposes the hot rolling wire rod for haling the excellent in wire-drawing workability under a processing conditions.But in patent document 3, only focus on Hale the stringiness under processing special as silk, and for mostly important Q-tempering in bearing spring etc. after Resistance to hydrogen embrittlement does not give any consideration.
Existing technical literature
Patent document
Patent document 1: Japanese Unexamined Patent Publication 2004-143482 bulletin
Patent document 2: Japanese Unexamined Patent Publication 2006-183137 bulletin
Patent document 3: Japanese Unexamined Patent Publication 2007-231347 bulletin
Summary of the invention
Subject to be solved by the invention
The present invention is formed in view of above-mentioned such situation, it is intended that providing a kind of rolled stock, being includes hot rolling Still have excellent with the cold coiling former material of the high-strength spring including the two even if inhibiting the additive amount of alloying element Wire-drawing workability, and excellent corrosion fatigue characteristic can be played after Q-tempering.
Means for solving the problems
Reach the high-strength spring rolled stock of the invention of the above subject, which is characterized in that contain in terms of quality %
C:0.39~0.65%,
Si:1.5~2.5%,
Mn:0.15~1.2%,
P: be higher than 0% and below 0.015%,
S: be higher than 0% and below 0.015%,
Al:0.001~0.1%,
Cu:0.1~0.80%,
Ni:0.1~0.80%, surplus are iron and inevitable impurity,
Non-diffusing hydrogen amount be 0.40 mass ppm hereinafter,
Ferritic the area ratio expressed as a percentage meets following (1) formulas, and total face of bainite and martensite Product rate is 2% or less.
× 100 ... (1) ferrite the area ratio < { (0.77- [C])/0.77- [C]/3+0.08 }
Wherein, in above-mentioned (1) formula, [masurium] means the content that each element is indicated with quality %.
High-strength spring rolled stock of the invention, furthermore it is preferred that in terms of quality % containing belong to following (a), (b), (c), a kind or more of any one of (d).
(a) Cr: it is higher than 0% and below 1.2%；
(b) Ti: it is higher than 0% and below 0.13%；
(c) B: it is higher than 0% and below 0.01%；
(d) from Nb: be higher than 0% and below 0.1%, Mo: being higher than 0% and below 0.5% and V: be higher than 0% and It is selected in 0.4% or less the group constituted at least one kind of.
In addition, high-strength spring rolled stock of the invention, preferably ideal critical diameter DiFor 65~140mm, ideal is faced Boundary diameter DiIt is calculated when without B using following (2) formulas, is calculated when containing B using following (3) formulas.In addition, indicated in following formula Among element, when having the element not contained in rolled stock of the invention, calculated its content as 0%.
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])
×(1+3×[Mo])…(2)
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])×(1+3×[Mo])
× (6.849017-46.78647 × [C]+196.6635 × [C]2
- 471.3978 × [C]3+587.8504×[C]4
- 295.0410 × [C]5)…(3)
Wherein, in above-mentioned (2), (3) formula, [masurium] means the content that each element is indicated with quality %.
The present invention also includes carrying out wire drawing with rolled stock for any one of the above high-strength spring, is quenched tempering Tensile strength 1900MPa or more high-strength spring silk material.
Invention effect
According to the present invention, even if not adding alloying element largely, because inhibiting the non-diffusing hydrogen amount in rolled stock, and press down The generation of the over-cooling structures such as bainite and martensite is made, so the wire-drawing workability of rolled stock is also excellent.In addition, of the invention Rolled stock is specifically exactly that C concentration is higher, more reduces ferritic face according to the ferritic the area ratio of C concentration appropriate adjustment Product rate, therefore wire drawing is carried out for the rolled stock, even if the high intensity that the silk material for having carried out Q-tempering is 1900MPa or more, Corrosion fatigue characteristic is also excellent.In such rolled stock, even if inhibiting steel product cost, the wire drawing for still being able to improve rolled stock adds The corrosion fatigue characteristic of work and silk material, therefore manufacturing is excellent, can inexpensively supply the extremely difficult generation of fatigue corrosion fracture High-intensitive spring, for example, the helical spring etc. of bearing spring as one of automobile part etc..
Detailed description of the invention
Fig. 1 is the figure for indicating C amount Yu the influence caused by resistance to hydrogen embrittlement of ferrite the area ratio.
Specific embodiment
The wire-drawing workability of rolled stock is usually influenced by the ductility of rolled stock.If blank lacks ductility, or deposits The ductility reduction in over-cooling structure is then broken when wire drawing and manufacturing is greatly reduced.Therefore, by improving prolonging for rolled stock Malleability can improve wire-drawing workability.
On the other hand, if corrosion occurs, pit occurs for steel surface, and leads to steel because refining caused by corrosion Line footpath attenuates.In addition, the hydrogen occurred due to corrosion invades in steel, the embrittlement of steel caused by hydrogen occurs.Fatigue corrosion fracture Using at these etch pits, refinement, steel embrittlement portion as starting point occur.Therefore, the resistance to hydrogen embrittlement and corrosion resistance for making steel improve, Fatigue corrosion fracture can be improved.
The inventors of the present invention carry out the factor of the ductility of influence steel, resistance to hydrogen embrittlement and corrosion resistance from various angles Research.Itself as a result, it has been found that, if suitably control rolled stock ferrite the area ratio and especially indicated with non-diffusible hydrogen amount Steel in both hydrogen amount, then the ductility of rolled stock improves, and to rolled stock wire drawing, implements resistance to hydrogen embrittlement when Q-tempering It greatly improves.In addition, also can be improved corrosion resistance by appropriate adjustment chemical composition, as a result, it has been found that corruption can be greatly improved Fatigue properties are lost, so as to complete the present invention.Hereinafter, being pressed for hydrogen amount, chemical composition in the tissue of rolled stock of the invention, steel Sequence is illustrated.
Ferritic structure easily becomes the thin domain of carbide after Q-tempering, if the thin domain of carbide generates, Become break origins as strength reduction portion.In addition, carbide has the ability for keeping hydrogen innoxious by capturing hydrogen, but carbon The thin domain of compound, which becomes, lacks this capacity locations, and hydrogen embrittlement is easy to happen, and be easy to cause fracture.In order at Q-tempering The formation for inhibiting the thin domain of carbide after reason, is uniformly dispersed carbide, needs the rank of the rolled stock before Q-tempering The evenly dispersed tissue of Duan Chengwei carbide.That is, it needs to make the pearlite for becoming the tissue of stratiform as ferrite and carbide The ratio of tissue increases, and reduces the ratio of ferritic structure.The inventors of the present invention's discovery, makes the area ratio of ferritic structure than rolling The ratio of obtained ferritic structure is reduced when letting cool afterwards, this lets cool after rolling for improving critically important on resistance to hydrogen embrittlement When obtained ferritic structure and C magnitude relation it is close.
For making C amount carry out the steel of various change, adjustment lets cool the ratio of obtained ferritic structure after rolling When show that the ratio that obtained ferritic structure is let cool after rolling is indicated by the right of following (1) formulas.Then, in the present invention Rolled stock in, have the feature that, control the ratio of ferritic structure to meet the relationship of following (1) formulas.Wherein, under It states in (1) formula, [masurium] is meant with the content of the quality % each element indicated.In addition, in the present specification, ferrite The area ratio means ratio expressed as a percentage.
× 100 ... (1) ferrite the area ratio < { (0.77- [C])/0.77- [C]/3+0.08 }
Fig. 1 is to indicate C amount and the influence caused by resistance to hydrogen embrittlement of ferrite the area ratio based on aftermentioned embodiment data Figure.Let cool as shown in the straight line of Fig. 1, after rolling obtained ferritic structure ratio have with C quantitative change is high and that reduces incline To higher in C amount in rolled stock of the invention, ferritic the area ratio more reduces has great feature on this point.? In the more steel of C amount, this brittle viewpoint especially is easy from martensitic structure, it is also desirable to make the ratio of ferritic structure It further decreases.The fewer ferrite the area ratio the better, is also possible to 0%.
In addition, preferably making the ratio of ferritic structure than letting cool obtained iron element after rolling in rolled stock of the invention The ratio of body tissue reduces by 10% or more, that is, preferably satisfies following (1-2) formulas.
Ferrite the area ratio≤{ (0.77- [C])/0.77- [C]/3+0.08 } × 100 × 0.9 ... (1-2)
In rolled stock of the invention, if the over-cooling structure of bainite and martensite etc. is more, wire-drawing workability substantially drops It is low.It therefore, also will be in 2 area % hereinafter, preferably 1 area % is hereinafter, most preferably 0 area % even if containing these tissues.
Rolled stock of the invention, inhibit ferrite, bainite and martensite generation, other than tissue be pearlite.
Secondly, being illustrated for the hydrogen amount in rolled stock of the invention.In rolled stock of the invention, make non-diffusible hydrogen Amount is 0.40 mass ppm or less.If non-diffusible hydrogen amount is more, hydrogen will be assembled around the field trash, segregated zone in rolled stock, Fine crackle occurs, the wire-drawing workability of rolled stock reduces.In addition, further intrusion is until steel if non-diffusible hydrogen amount is more The allowance that the hydrogen of embrittlement occurs for material is reduced, and it is crisp to also result in steel even as a small amount of hydrogen that spring invades in use Change and occur, premature failure easy to form, resistance to hydrogen embrittlement reduces.Non-diffusing hydrogen amount is preferably 0.35 mass ppm hereinafter, more preferably 0.30 mass ppm or less.The non-diffusing hydrogen amount the few more preferred, but reaches 0 mass ppm and have any problem, and lower limit is 0.01 mass ppm Left and right.
In addition, so-called non-diffusible hydrogen, is the hydrogen amount of the measurement of the method as described in aftermentioned embodiment, and specifically, the meaning When being with 100 DEG C/h of heating steel, the total amount for the hydrogen amount released at 300~600 DEG C.
High-strength spring rolled stock of the invention is the low-alloy steel for inhibiting the content of alloying element, chemical composition It is as follows.In addition, the present invention also includes that the silk material of wire drawing and Q-tempering is carried out for the rolling material, chemical composition and rolling The chemical composition of material is identical.
C:0.39~0.65%
C is to ensure that element required for the intensity of spring silk material, and for generating as the fine of hydrogen trap site It is also needed on carbide.From this viewpoint, C amount is set to 0.39% or more.The preferred lower limit of C amount is 0.45% More than, more preferably 0.50% or more.But if C amount is superfluous, also it is easy to generate coarse retained austenite after Q-tempering , there is the case where reducing resistance to hydrogen embrittlement instead in the carbide not being dissolved.In addition, C is also the element for deteriorating corrosion resistance, Therefore, in order to improve bearing spring as final product etc. spring product corrosion fatigue characteristic and need to inhibit C amount.From This viewpoint is set out, and C amount is set to 0.65% or less.The preferred upper limit of C amount be 0.62% hereinafter, more preferably 0.60% with Under.
Si:1.5~2.5%
Si is for ensuring that element required for intensity, and has the effect of keeping carbide fine.In order to effectively send out Such effect is waved, Si amount is set to 1.5% or more.The preferred lower limit of Si amount be 1.7% or more, more preferably 1.9% with On.On the other hand, Si is also the element for promoting decarburization, if therefore Si amount it is superfluous, the decarburized layer of steel surface, which is formed, to be promoted, The peeling operation for eliminating decarburized layer is needed, the increase of manufacturing cost is incurred.In addition, non-solid solution carbides also become more, it is hydrogen resistant Brittleness reduces.From this viewpoint, Si amount is set to 2.5% or less.The preferred upper limit of Si amount is 2.3% hereinafter, more excellent 2.2% is selected as hereinafter, further preferably 2.1% or less.
Mn:0.15~1.2%
Mn is utilized as deoxidant element, and is reacted with the S in steel as harmful element and formed MnS, is to be beneficial to S Innoxious element.In addition, Mn also contributes to the element of intensity raising.In order to effectively play these effects, by Mn amount It is set to 0.15% or more.The preferred lower limit of Mn amount is 0.2% or more, more preferably 0.3% or more.But if Mn amount is superfluous, Then toughness reduces, steel embrittlement.From this viewpoint, Mn amount is set to 1.2% or less.The preferred upper limit of Mn amount is 1.0% hereinafter, more preferably 0.85% hereinafter, further preferably 0.70% or less.
P: it is higher than 0% and below 0.015%
P is to make rolled stock, i.e. the harmful element of the ductility deterioration such as windability of wire rod, and therefore, it is desirable to as few as possible.Separately Outside, P is easy to incur embrittlement of grain boundaries in cyrystal boundary segregation, and hydrogen causes crystal boundary to be easily broken off, and brings adverse effect to resistance to hydrogen embrittlement.From This viewpoint is set out, and P amount is set to 0.015% or less.The preferred upper limit of P amount is 0.010% hereinafter, more preferably 0.008% or less.The P amount the few more preferred, but usually contains 0.001% or so.
S: it is higher than 0% and below 0.015%
S and above-mentioned P are again it is make the harmful element of the ductility deterioration such as windability of rolled stock, therefore, it is desirable to as far as possible It is few.In addition, S is easy to incur embrittlement of grain boundaries in cyrystal boundary segregation, hydrogen is easy to cause intercrystalline cracking, brings unfavorable shadow to resistance to hydrogen embrittlement It rings.From this viewpoint, S amount is set to 0.015% or less.The preferred upper limit of S amount is 0.010% hereinafter, more preferably 0.008% or less.The S amount the few more preferred, but usually contains 0.001% or so.
Al:0.001~0.1%
Al is added mainly as deoxidant element.In addition, reacting with N and forming AlN, keep solid solution N innoxious, and also have Help the miniaturization of tissue.In order to fully play these effects, Al amount is set to 0.001% or more.Al amount it is preferred under It is limited to 0.002% or more, more preferably 0.005% or more.But Al and Si also promote the element of decarburization, therefore It largely needs to inhibit Al amount in the spring steel containing Si, Al amount is set to 0.1% or less in the present invention.Al amount it is preferred The upper limit is for 0.07% hereinafter, more preferably 0.030% hereinafter, particularly preferably 0.020% or less.
Cu:0.1~0.80%
Cu is effective element for the inhibition of superficial decarbonization and the raising of corrosion resistance.Therefore Cu amount be set to 0.1% with On.The preferred lower limit of Cu amount is 0.15% or more, more preferably 0.20% or more, further preferably 0.25% or more.But It is that, if Cu excessively contains, crackle or increased costs occur for when hot-working.Therefore, Cu amount is set to 0.80% or less.Cu Amount the preferred upper limit be 0.70% hereinafter, more preferably 0.60% hereinafter, further preferably 0.48% hereinafter, particularly preferably For 0.35% hereinafter, most preferably 0.30% or less.
Ni:0.1~0.80%
Ni is same as Cu, and the raising of inhibition and corrosion resistance for superficial decarbonization is effective element.Therefore by Ni amount It is set to 0.1% or more.The preferred lower limit of Ni amount is 0.15% or more, more preferably 0.20% or more, further preferably 0.35% or more, most preferably 0.45% or more.But if Ni is excessively contained, increased costs.Therefore Ni amount is set to 0.80% or less.The preferred upper limit of Ni amount is for 0.70% hereinafter, more preferably 0.60% hereinafter, further preferably 0.55% Hereinafter, being also still more preferably 0.48% or less, 0.35% or less, 0.30% or less.
The basis of rolled stock of the invention is for example above-mentioned, and surplus is substantially iron.But certainly allow because raw material, The situation of goods and materials, manufacturing equipment etc. and mixed inevitable impurity is included in steel.Spring rolled stock of the invention, i.e., Make the alloying element for inhibiting Cu etc., by above-mentioned chemical composition, can also reach high-intensitive and excellent windability and hydrogen resistant Brittleness, but depending on the application, for the purpose of the raising of corrosion resistance etc., can also be allowed to also contain following elements.
Cr: it is higher than 0% and below 1.2%
Cr is effective element for the raising of corrosion resistance.In order to effectively play such effect, Cr amount is preferably 0.01% or more, more preferably 0.05% or more, further preferably 0.10% or more.But the carbide of Cr generates tendency By force, unique carbide is formed in steel, and is the element for being easy to permeate with high concentration in cementite.Although containing few The Cr of amount is effective, but in high-frequency heating, because the heating time of quenching process is the short time, makes carbide, carburizing The austenitizing that body etc. penetrates into base material is easy insufficient.Therefore, if largely containing Cr, Cr system carbide, metal Cr are highly concentrated The not molten residual of the cementite of degree ground solid solution occurs, and becomes stress raiser and is easily broken off, can make hydrogen embrittlement deterioration.Cause This, Cr amount is preferably 1.2% hereinafter, more preferably 0.8% hereinafter, further preferably 0.6% or less.
Ti: it is higher than 0% and below 0.13%
Ti reacts with S and forms sulfide, for realizing that the innoxious of S is useful element.In addition, Ti forms carbon nitridation Object also has the effect of miniaturizeing tissue.In order to effectively play such effect, Ti amount is preferably 0.02% or more, more Preferably 0.05% or more, further preferably 0.06% or more.But if Ti amount is superfluous, coarse Ti sulfide is formed And deteriorate ductility.Therefore, Ti amount is preferably 0.13% or less.From the viewpoint of cutting down cost, preferably 0.10% with Under, more preferably 0.09% or less.
B: it is higher than 0% and below 0.01%
B is that hardenability improves element, in addition has the effect of making old austenite recrystallization intercrystalline strengthening, contributes to inhibit disconnected The element split.In order to effectively play such effect, B amount is preferably 0.0005% or more, more preferably 0.0010% or more. But even if B amount is superfluous, said effect is also saturation, thus B amount preferably 0.01% hereinafter, more preferably 0.0050% with Under, further preferably 0.0040% or less.
Nb: it is higher than 0% and below 0.1%
Nb and C and N forms carbonitride, is essentially to facilitate the element of tissue miniaturization.In order to effectively play in this way Effect, Nb amount be preferably 0.003% or more, more preferably 0.005% or more, further preferably 0.01% or more.But If Nb amount is superfluous, coarse carbonitride forms and deteriorates the ductility of steel.Therefore, Nb amount is preferably 0.1% or less.From From the perspective of cutting down cost, preferably 0.07% or less.
Mo: it is higher than 0% and below 0.5%
Mo is also same as Nb, forms carbonitride with C and N, contributes to the element of tissue miniaturization.In addition for tempering Intensity afterwards ensures to be also effective element.In order to effectively play such effect, Mo amount is preferably 0.15% or more, more excellent It is selected as 0.20% or more, further preferably 0.25% or more.But if Mo amount is superfluous, coarse carbonitride is formed, steel The ductility deterioration such as windability.Therefore, Mo amount is preferably 0.5% hereinafter, more preferably 0.4% or less.
V: it is higher than 0% and below 0.4%
The intensity that V contributes to improves and the element of crystal grain miniaturization.In order to effectively play such effect, V amount is preferred It is 0.1% or more, more preferably 0.15% or more, further preferably 0.20% or more.But if V amount is superfluous, cost increases Add.Therefore, V amount is preferably 0.4% hereinafter, more preferably 0.3% or less.
Nb, Mo and V can individually contain, and two or more can also combine and contain.
In addition, rolled stock of the invention contains O and N as inevitable impurity, amount is preferably adjusted to following ranges.
O: it is higher than 0% and below 0.002%
If O amount is superfluous, coarse Al is formed2O3Fatigue properties are caused adverse effect by equal oxides system field trash.Cause This, the upper limit of O amount is preferably 0.002% hereinafter, more preferably 0.0015% hereinafter, further preferably 0.0013% or less. On the other hand, the lower limit of O amount is usually 0.0002% or more (preferably 0.0004% or more) in industrial production.
N: it is higher than 0% and below 0.007%
N amount is more, more can be formed together coarse nitride with Ti and Al, bring adverse effect to fatigue properties.Therefore, It is preferred that N amount is few as much as possible, such as or 0.007% hereinafter, more preferably 0.005% or less.On the other hand, if excessively N amount is reduced, then productivity significantly reduces.In addition, N and Al are formed together nitride, facilitate the miniaturization of crystal grain.From such Viewpoint is set out, and preferably making N amount is 0.001% or more, more preferably 0.002% or more, further preferably 0.003% or more.
In addition, in rolled stock and silk material of the invention, preferably by following (2) formulas or the ideal critical diameter of (3) formula expression DiFor 65~140mm.In order to do not have to rolled stock carry out soft annealing and wire drawing is used as spring with former material, need to be subcooled It is following so as to which broken string etc. does not occur in wire drawing that tissue is reduced to regulation.If ideal critical diameter DiHeight, then hardenability is got higher, and is easy There is over-cooling structure, therefore ideal critical diameter DiThe upper limit be preferably 140mm or less.Ideal critical diameter DiThe upper limit it is more excellent 135mm is selected as hereinafter, further preferably 130mm is hereinafter, particularly preferably 120mm or less.On the other hand, as spring in order to It is quenched to inside, it is important that ensure certain hardenability.Therefore ideal critical diameter DiLower limit be preferably 65mm or more, more Preferably 70mm or more, further preferably 80mm or more.
Ideal critical diameter Di, when being free of B, use following (2) formulas of ASTM A255 defined.In addition, containing B When, it needs to add on the right of above-mentioned (2) formula multiplied by boron factor B.F. specified in ASTM A255-02, uses following (3) formulas Calculate ideal critical diameter Di。
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])
×(1+3×[Mo])…(2)
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])
×(1+3×[Mo])
× (6.849017-46.78647 × [C]+196.6635 × [C]2
- 471.3978 × [C]3+587.8504×[C]4
- 295.0410 × [C]5)…(3)
Wherein, in above-mentioned (2), (3) formula, [masurium] means the content that each element is indicated with quality %.
Next, being illustrated for the manufacturing method of rolled stock of the invention.Melting has the steel of above-mentioned chemical composition, In continuously casting, split rolling method, the such a series of process of hot rolling, by adjusting the hydrogen amount in (A) molten steel stage, (B) cogging At least one of homogenize process temperature and time before rolling, 400~100 DEG C of average cooling rate after (C) hot rolling, then It is capable of the non-diffusing hydrogen amount of controlled rolling material.In addition, passing through coiled material coiling temperature (TL), (ii) aforementioned TL after rolling (i) ~650 DEG C of average cooling rate, the average cooling rate that 650~400 DEG C of (iii) are adjusted, then can be by rolled stock Tissue, i.e. ferrite, martensite and bainite adjust to above range.
In order to reduce the hydrogen in the steel after solidification, need to remove the hydrogen in steel by diffusion, in order to make hydrogen from steel table Face releases, it should accelerate the diffusion velocity of hydrogen, high temperature and for a long time heating are effective.Specifically, as the hydrogen reduced in steel The method of amount, can enumerate the adjustment in molten steel stage, after solidification the adjustment in the stage of 1000 DEG C or more of continuous cast materials, The adjustment of heating period before hot rolling is rolling the adjustment in the stage in heating and the adjustment of the cooling stage after rolling. Wherein, particularly effective is to carry out the reduction of non-diffusible hydrogen of (A) as shown below~(C) to handle at least one.
(A) it is de-gassed in molten steel processing, the hydrogen amount in molten steel is made to reach 2.5 mass ppm or less.
For example, assembly has the vacuum tank of two dip-tubes in casting ladle, from one effectively in double refining process The dip-tube side spray feed Ar gas of side, carries out making vacuum outgas of the molten steel to vacuum tank circulation using its buoyancy.The hydrogen of this method Removing ability and field trash reduce excellent.Hydrogen amount in molten steel is preferably 2.0 mass ppm hereinafter, more preferably 1.8 mass ppm Hereinafter, further preferably 1.5 mass ppm are hereinafter, particularly preferably 1.0 mass ppm or less.
(B) at 1100 DEG C or more, preferably 1200 DEG C or more homogenize process 10 hours or more carried out before split rolling method.
(C) 400~100 DEG C of average cooling rate after rolling is 0.5 DEG C/sec hereinafter, preferably 0.3 DEG C/sec or less.
It when the basal area of especially steel is big, needs to heat for a long time, if but long-time heating steel, decarburization rush Into, therefore in this case, it preferably carries out above-mentioned (A) and reduces the hydrogen amount in steel.
In addition, in order to make the tissue in rolled stock, i.e., ferrite, bainite, martensite the area ratio be above range, it is excellent Choosing adjusts rolling condition as follows, preferably all meets rolling condition as (i) below~(iii).
(i) TL:900 DEG C of coiling temperature or more of the coiled material before cooling starts
In order to reduce ferritic ratio, need to make the coiled material coiling temperature TL austenite one phase before cooling start.Cause This TL is more preferably 910 DEG C or more, further preferably 930 DEG C or more.The upper limit of TL is not particularly limited, although also according to finish to gauge Temperature is different, but substantially 1000 DEG C or so.
(ii) average cooling rate at TL~650 DEG C: 2~5 DEG C/sec
Temperature field at TL~650 DEG C needs to improve cooling velocity and inhibits iron plain to make pearlitic transformation The generation of body.Therefore, the average cooling rate at TL~650 DEG C is preferably 2 DEG C/sec or more, and more preferably 2.3 DEG C/sec or more, Further preferably 2.5 DEG C/sec or more.But if excessively improving the cooling velocity at TL~650 DEG C, it is easy to appear geneva The over-cooling structure of body and bainite etc..Therefore the average cooling rate at TL~650 DEG C is preferably 5 DEG C/sec hereinafter, more preferably 4.5 DEG C/sec hereinafter, further preferably 4 DEG C/sec or less.
(iii) average cooling rate at 650~400 DEG C: 2 DEG C/sec or less
Furthermore it is preferred that the cooling velocity that over-cooling structure starts at 650~400 DEG C generated is slow.At 650~400 DEG C Average cooling rate be preferably 2 DEG C/sec hereinafter, more preferably 1.5 DEG C/sec hereinafter, further preferably 1 DEG C/sec or less.This is flat The lower limit of equal cooling velocity is not particularly limited, and for example, 0.3 DEG C/sec or so.
Such as it in order to manufacture helical spring used in automobile etc., needs to carry out the rolling material the i.e. wire drawing of line processing and adds Work and manufacture silk material, such as after in cold coiling spring being on-line machining, carry out the Q-tempering of high-frequency heating etc., such silk material It is also included in the present invention.For example, wire drawing is carried out for the rolling material with 5~35% or so sectional shrinkage, It quenches at 900~1000 DEG C or so, is tempered at 300~520 DEG C or so afterwards.Hardening heat is in order to make fully austenite Change and preferably 900 DEG C or more, in order to prevent coarse grains and preferably 1000 DEG C or less.In addition the heating temperature being tempered, Range in a manner of meeting the target value of silk material intensity at 300~520 DEG C is set as temperature appropriate.In addition, passing through When high-frequency heating carries out Q-tempering, the time of Q-tempering is respectively 10~60 seconds or so.
The obtained silk material of the invention can be realized the high-tensile of 1900MPa or more.Tensile strength can be excellent It is selected as 1950MPa or more, more preferably 2000MPa or more.The upper limit of tensile strength is not particularly limited, but substantially 2500MPa or so.In addition silk material of the invention is because use rolled stock of the invention, even if being the height of 1900MPa or more Intensity can also play excellent corrosion fatigue characteristic.
The application is based on Japanese Patent Application No. 2013-272569 claims priority filed on December 27th, 2013 The interests of power.Filed on December 27th, 2013 in the whole of Japanese Patent Application No. 2013-272569 specification Hold, in this application for referring to and quoting.
Embodiment
Hereinafter, enumerating embodiment further illustrates the present invention.The present invention is not limited by the examples below, and can accorded with Implementation can certainly suitably be changed in the range of aforementioned, aftermentioned purport by closing, these are all contained in technology of the invention In range.
The steel of the chemical composition shown in converter melting table 1~3 after continuously casting, carry out homogeneous at 1100 DEG C or more Change processing.After homogenize process, split rolling method is carried out, to carry out hot rolling after 1100~1280 DEG C of heating, obtains diameter 14.3mm Wire rod, i.e. rolled stock.Cooling condition such as table of the molten steel whether there is or not the coiled material coiling temperature TL after degassing process, hot rolling and after batching Described in 4~6, in addition describing in one column of homogenize process as the test example of " implementation " is the homogenize process 10 carried out at 1100 DEG C Hour or more, it describes in the test example for "-", the time of the homogenize process at 1100 DEG C is lower than 10 hours.
For obtained wire rod, that is, rolled stock, identifies tissue by main points below, measure non-diffusing hydrogen amount, and measure Wire-drawing workability.
(1) identification of tissue
The cross section of rolled stock is polished, after being etched with corrosive liquid, observes microscopic structure, measurement iron element with optical microscopy The area of body tissue, bainite and martensite tissue (hereinafter, by bainite structure and martensitic structure and referred to as over-cooling structure) Rate.Measurement is carried out in the position away from surface layer 1mm depth.Field of view is 300 μm of 400 μ m, is measured in 5 visuals field, Using its average value as the ratio of each tissue.In addition, the ratio of pearlitic structrure, by subtracting ferrite and mistake from 100% The ratio of cold tissue and acquire.
(2) non-diffusing hydrogen amount
Wide 20mm × long 40mm test film is cut from the rolled stock.Using gas chromatographic analysis device, with 100 DEG C/h heating rate heat up the test film, the releasing hydrogen amount at 300~600 DEG C of measurement, as non-diffusing hydrogen amount.
(3) wire-drawing workability
Wire-drawing workability is evaluated by the contraction percentage of area of tension test.No. JIS14 is cut from the rolled stock Test film, it then follows JIS Z2241 (2011) carries out tension test with universal testing machine with crosshead speed 10mm/ points of condition, Measure section shrinking percentage RA.
Then, the rolled stock wire drawing to diameter 12.5mm is subjected to cold drawing processing, and carries out Q-tempering.It is described The sectional shrinkage of wire drawing about 23.6%, the condition of Q-tempering is as follows.
Q-tempering condition
High-frequency heating
Heating speed: 200 DEG C/sec
Quenching: 950 DEG C, 20 seconds, water was cooling
Tempering: 300~520 DEG C of each temperature, 20 seconds, water was cooling
For the silk material after wire drawing and Q-tempering, the evaluation of tensile strength, resistance to hydrogen embrittlement and corrosion resistance is carried out.
(4) measurement of tensile strength
Silk material after Q-tempering is cut to specific length, distance 200mm, tensile speed 5mm/min between chuck, it then follows JIS Z2241 (2011) carries out tension test.
(5) evaluation of resistance to hydrogen embrittlement
From the silk material after Q-tempering, wide 10mm × thickness 1.5mm × long 65mm test film is cut.Then, passing through 4 Point bending to the stress of test film load 1400MPa in the state of, by the test film be immersed in 0.5mol/L sulfuric acid and In the mixed solution of the potassium rhodanide of 0.01mol/L.It is additional than saturated calomel electrode (Saturated using potentiostat Calomel Electrode, SCE) low -700mV voltage, the rupture time that measurement occurs until crackle.
(6) evaluation of corrosion resistance
From the silk material after Q-tempering, diameter 10mm × long 100mm test film is cut with machining.For the examination It tests piece and 8 hours brine sprays is carried out with 5%NaCl aqueous solution, keep 16 small under 35 DEG C, the moist environment of relative humidity 60% When, it being recycled in this, as 1, all 7 circulations is repeated, the weight difference of the test film of front and back is tested in measurement, as Corrosion weight loss.
Above-mentioned (1)~(6) as the result is shown in table 4~6.
[table 1]
[table 2]
[table 3]
[table 4]
[table 5]
[table 6]
Test No.1~4,7~11,15~18,21~25,33,34,37~40,45~47,49~53,55~60,65 ~81, because being to obtain the steel of appropriate adjustment by above-mentioned preferred manufacturing condition manufacture chemical composition, non-diffusing hydrogen amount, The area ratio of ferrite and over-cooling structure meets important document of the invention.Therefore, the contraction percentage of area in the tension test of rolled stock RA is 30% or more, in addition excellent in wire-drawing workability carries out wire drawing for rolled stock, is quenched silk material obtained from tempering Excellent tensile strength with 1900MPa or more.In addition, the silk material after Q-tempering is in the evaluation test of resistance to hydrogen embrittlement, Rupture time is 1000 seconds or more, and the corrosion weight loss in the evaluation test of corrosion resistance is 5.0g hereinafter, resistance to hydrogen embrittlement and corrosion resistant Corrosion is excellent.In addition, so-called " reduced rate " in table 4~6 is following value, that is, the value on the right of formula (1) expressed as a percentage And ratio of the difference of the value of actual ferrite the area ratio relative to the value on the right of formula (1).
On the other hand, in the example other than above-mentioned test No., because of the chemical composition of steel, non-diffusing hydrogen amount, ferrite At least any one important document of the area ratio and over-cooling structure the area ratio is unsatisfactory for important document of the invention, so the wire drawing of rolled stock adds Work, the tensile strength of silk material, resistance to hydrogen embrittlement, corrosion resistance at least any one characteristic be difference result.
No.5,6,19,20 are not because carry out the reduction processing of above-mentioned non-diffusible hydrogen, the non-diffusible hydrogen in rolled stock Measure more, wire-drawing workability reduction.
Because the average cooling rate from coiling temperature TL to 650 DEG C is slow, ferrite the area ratio is got higher for No.12,26, Resistance to hydrogen embrittlement reduces.Because the average cooling rate from coiling temperature TL to 650 DEG C is fast, over-cooling structure increases for No.13,27 Add, wire-drawing workability reduces.Because 650~400 DEG C of average cooling rate is fast, over-cooling structure increases, and draws for No.14,28 Silk processability reduces.
The over-cooling structure of No.29~31 increases, and wire-drawing workability reduces.The C amount of No.32 is few, and the tensile strength of silk material is not Foot.The C amount of No.35 is more, and retained austenite generates, and resistance to hydrogen embrittlement reduces.The Si amount of No.36 is few, and the tensile strength of silk material is insufficient.
The Mn amount of No.41 is more, and toughness reduces, and resistance to hydrogen embrittlement reduces.The P amount and S amount of No.42 is more, causes embrittlement of grain boundaries, resistance to Hydrogen brittleness reduces.The S amount of No.43 is more, causes embrittlement of grain boundaries, and resistance to hydrogen embrittlement reduces.No.44 adds Cu, Ni because of no, Corrosion resistance reduces.
No.48 is because without addition Ni, corrosion resistance is reduced.The Cr amount of No.54 is more, Cr system carbide, metal Cr Occurred with the not molten residual of the cementite of high concentration solid solution, become stress raiser, resistance to hydrogen embrittlement reduces.
The average cooling rate of coiling temperature TL~650 DEG C of No.61~64 is slow, and ferrite the area ratio increases, resistance to hydrogen embrittlement Property reduce.
Industrial availability
Rolled stock and silk material of the invention can be suitable for helical spring used in automobile etc., such as engine and suspension etc. Used valve spring, bearing spring etc., it is industrially useful.

Claims (5)

1. a kind of high-strength spring rolled stock, which is characterized in that contained in terms of quality %
C:0.39~0.65%,
Si:1.5~2.5%,
Mn:0.15~1.2%,
P: be higher than 0% and below 0.015%,
S: be higher than 0% and below 0.015%,
Al:0.001~0.1%,
Cu:0.1~0.80%,
Ni:0.1~0.80%, surplus are iron and inevitable impurity,
Non-diffusing hydrogen amount be 0.40 mass ppm hereinafter,
Following (1) formulas, and total the area ratio of bainite and martensite are met by the ferritic the area ratio that percentage indicates 2% hereinafter,
× 100 ... (1) ferrite the area ratio < { (0.77- [C])/0.77- [C]/3+0.08 }
Wherein, in above-mentioned (1) formula, [masurium] means the content that each element is indicated with quality %.
2. high-strength spring rolled stock according to claim 1, wherein in terms of quality % also containing belong to following (a), (b), a kind or more of any one of (c), (d):
(a) Cr: it is higher than 0% and below 1.2%；
(b) Ti: it is higher than 0% and below 0.13%；
(c) B: it is higher than 0% and below 0.01%；
(d) from Nb: being higher than 0% and below 0.1%, Mo: being higher than 0% and below 0.5% and V: being higher than 0% and 0.4% It is selected in following constituted group at least one kind of.
3. high-strength spring rolled stock according to claim 1 or 2, wherein use following (2) formulas when being free of B, contain Following (3) formula calculated ideal critical diameter D are used when BiFor 65~140mm,
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])×(1+3×[Mo])…(2)
Di=25.4 × (0.171+0.001 × [C]+0.265 × [C]2)
×(3.3333×[Mn]+1)×(1+0.7×[Si])
×(1+0.363×[Ni])×(1+2.16×[Cr])
×(1+0.365×[Cu])×(1+1.73×[V])×(1+3×[Mo])
× (6.849017-46.78647 × [C]+196.6635 × [C]2
- 471.3978 × [C]3+587.8504×[C]4
- 295.0410 × [C]5)…(3)
Wherein, in above-mentioned (2), (3) formula, [masurium] means the content that each element is indicated with quality %.
4. a kind of high-strength spring silk material is that high-strength spring of any of claims 1 or 2 is drawn with rolled stock Silk, is quenched the high-strength spring silk material of the tensile strength 1900MPa or more of tempering.
5. a kind of high-strength spring silk material is to carry out wire drawing with rolled stock for high-strength spring as claimed in claim 3, It is quenched the high-strength spring silk material of the tensile strength 1900MPa or more of tempering.
CN201811092603.3A 2013-12-27 2014-12-10 High-strength spring rolled stock and the high-strength spring silk material for having used it Pending CN109112262A (en)

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