CN1696326A - Cold work tool steel - Google Patents

Abstract

Cold work tool steel of the present invention comprises 0.4<=K value<=2.6 (K value Cr(wt %)-6.8C (wt %)), 15.5<=L value<=21.0 (L value=Cr(wt %)+15.5C (wt %), 0.60 wt %<=Si<=2.0 wt %, 0.10 wt %<=Mn<=1.0 wt %, 0.03 wt %<S<=0.2 wt %, 1.25 wt %<Mo+0.5 W<3.0 wt %, 0.05 wt %<=V<=1.0 wt %, and the balance Fe and inevitable impurities, in which the highest hardness obtained by tempering at 450 DEG C. or higher after quenching is HRC 61 or more.

Description

Cold work tool steel

Technical field

The invention relates to cold work tool steel (cold work tool steel), in particular to the cold work tool steel that is fit to the cold mould of various differences, cold forging piercing die for example, the shaping die of high-tensile steel plate, bending die, cold forging die, type satin mould, screw thread rolls (system) mould, the drift member, cutter cracks, the lead frame blanking die, gauge, the drift of extending deeply, the bending die drift, shear blade, the stainless steel bending die, the mould of extending, cold pressing and use the plastic working instrument, the gear drift, the cam part, the blanking punching die, the step-feeding blanking die, the shrouding of silt particle feed-in machine, screw member, the rotating disk of concrete spraying machine, IC seals mould, and require the precision stamping mould of high dimensional accuracy, and (for example CVD handles through surface treatment, PVD handles or TD handles) the employed above-mentioned cold mould in back.

Background technology

Disperse a large amount of high rigidity carbide by crystallization or precipitation, can strengthen wear resistant, and can be used on the various different purposes (for example cold forging piercing die, cold forging die etc.) that require wear resistant or anti-wiping stickiness with the cold work tool steel of JIS steel SKD 11 expressions; Yet known cold work tool steel still has following point: (1) toughness deficiency; (2) can make formation condition sclerosis etc. will weaken mould hardness; And the fracture possibility of (3) line cutting electrodischarge machining(E.D.M.).

Therefore, propose various method traditionally and solve these problems, for example quote patent 1 as proof and disclose a kind of cold work tool steel, comprise C:0.75 to 1.75wt%, Si:0.5 to 3.0wt%, Mn:0.1 to 2.0wt%, Cr:5.0 to 11.0wt%, Mo:1.3 to 5.0wt%, V:0.1 to 5.0wt%, and remainder Fe and impurity, it is tempering under 450 ℃ or higher temperature; Quote that also illustrated in the patent 1 can be by with the minimized toughness that strengthens of main congruent melting carbide as proof, and can adjust when respectively forming, significantly promote life tools and electrodischarge machining(E.D.M.) by tempering under 450 ℃ or higher temperature to promote secondary hardening hardness (secondary hardeninghardness).

Quote patent 2 as proof and disclose a kind of cold work tool steel with a predetermined composition, it has 100 μ m or the littler glutinous poly-glutinous poly-size partly of carbide; Quote patent 2 as proof and also disclose the fracture of carbide and can be set in 100 μ m or littler and suppressed, to prolong life tools by sticking poly-size.

Quote patent 3 as proof and disclose a kind of high rigidity cold work tool steel with a predetermined composition, wherein the α value (=0.706+0.541C-0.063Cr+0.033Mo-0.232V) be 0.7 to 1.0, and β value (=Mo equivalent+1.9V equivalent) is 3.0 to 6.0; Quote as proof patent 3 also illustrate carbide of poor quality and glutinous poly-carbide formation can by α value and β value are set in these scopes are improved and hard surface layer between adhesion.

Quote patent 4 as proof and disclose a kind of high rigidity cold work tool steel with a predetermined composition, wherein the retained austenite of 5～35vol.% (retained austenite) is to be 0.01 to 2 μ m and being scattered here and there equably with median size; Quote patent 4 as proof and also illustrate that the retained austenite by the homodisperse predetermined amount can promote fatigue resistance.

Moreover, quote patent 5 as proof and disclose a kind of high rigidity cold work tool steel with a predetermined composition, wherein when reducing C content, can add the high speed cutting element, to improve processibility; Quote patent 5 as proof and also illustrate that unrelieved stress can utilize high tempering to remove, to prevent because of the fracture due to the electrodischarge machining(E.D.M.).

[quoting patent 1 as proof] Japanese patent application case publication number S59-179762

[quoting patent 2 as proof] Japanese patent application case publication number 2002-12952

[quoting patent 3 as proof] Japanese patent application case publication number 2000-073142

[quoting patent 4 as proof] Japanese patent application case publication number 2004-035920

[quoting patent 5 as proof] Japanese patent application case publication number 2000-355737

The mould special requirement superior workability of experiment mould and miscellaneous goods numbering more is far more than die life, the letter speech, some service condition needs to guarantee the cold work tool steel of HRC 60 or bigger hardness, and HRC can still have and the general identical hardness of mould under possessing with any working method processing simplification of (comprising cutting, electrodischarge machining(E.D.M.) and line cutting electrodischarge machining(E.D.M.)).

Yet the known cold work tool steel of representing with SKD 11 is even still exist the problem of processibility extreme difference, because the crystallization carbide is the wear resistant that disperses in a large number in the hope of guaranteeing to be scheduled under as-annealed condition; Again, during online cutting electrodischarge machining(E.D.M.), the crystallization carbide often causes thread breakage.

The also known wherein crystallization of prior art carbide amount is reduced to the material that can improve its workability; Yet, in this known materials, be difficult to guarantee reaching HRC 60 or bigger hardness during high tempering.On the other hand, tempering is when obtaining high rigidity at low temperatures when this material, and the stress that is produced in material during quenching just can't be removed, therefore, when we implemented electrodischarge machining(E.D.M.) or line cutting electrodischarge machining(E.D.M.) to the material of gained, unrelieved stress may overbalance and cause the fracture or the damage of material.

In quoting patent 1 disclosed cold work tool steel as proof, because of its crystallization carbide reduction than SKD more than 11, and composition can be adjusted, and so can guarantee HRC 60 or bigger hardness, and workability can be promoted to some degree; Yet even in quoting patent 1 disclosed cold work tool steel as proof, it is not enough that the improvement of workability is still disliked.Do not disclose the concrete device that when possessing high rigidity, can improve workability as for quoting patent 2 to 5 as proof.

Summary of the invention

So purpose of the present invention is to provide the cold work tool steel that has the superior workability of HRC 60 or bigger hardness after the tempering.

Cold work tool steel according to the present invention comprises: 0.4≤K value≤2.6 (K value=Cr (wt%)-6.8C (wt%)); ≤ L value≤21.0 15.5 (L value=Cr (wt%)+15.5C (wt%)); 0.60wt%＜Si≤2.0wt%; 0.10wt%≤Mn≤1.0wt%; 0.03wt%＜S≤0.2wt%; 1.25wt%＜Mo+0.5W＜3.0wt%; 0.05wt%≤V≤1.0wt%, and remainder Fe and inevasible impurity, wherein the highest hardness by the back tempering gained under 450 ℃ or higher temperature that quenches is HRC 61 or bigger value.

According to cold work tool steel of the present invention, because of the K value is to be set in pre-determined range, so behind the high tempering of HRC 61 or bigger value, can get highest hardness; Because of the L value is to be fixed in pre-determined range, thus processibility can be improved, and can suppress the fracture that online cutting electrodischarge machining(E.D.M.) is reached the standard grade; Moreover, because of except S, adding 0.6wt% or more Si in addition, so can obtain to be equal to or to be better than the processibility of known high speed cutting steel.

Description of drawings

Fig. 1 shows the relation between L value and the crystallization carbide content; And

Fig. 2 shows the relation between Si content and the processibility.

Embodiment

Now will describe preferred embodiment of the present invention in detail.Cold work tool steel of the present invention comprises column element, remainder Fe and inevasible impurity down; Shown in element kind, compositing range and restriction thereof to be added be the reasons are as follows.

(1) 0.4≤K value≤2.6 (K value=Cr (wt%)-6.8C (wt%))

The K value representation is the remaining Cr content in the matrix under suitable quenching temperature.When the K value less than 0.4 or greater than 2.6 the time, promptly reduced the formed carbide amount of secondary hardening when helping tempering so that the tempering of 450 ℃ or higher temperature to be difficult for obtaining hardness be the steel of HRC 61 or bigger value; The K value is preferably more than or equal to 0.45 and is less than or equal to 2.5 again, if more than or equal to 0.6 and be less than or equal to 2.4 better.

(2) 15.5≤L value≤21.0 (L value=Cr (wt%)+15.5C (wt%))

The content of crystallization carbide in the L value display material; The L value is bigger, and the content of crystallization carbide the more.When the L value less than 15.5 the time, not only because the crystallization carbide is difficult for forming, form change because of the matrix under suitable quenching temperature again simultaneously, so can't obtain necessary hardness; When the L value surpasses 21.0, represent that promptly the crystallization carbide content exceedingly increases, and has so then destroyed processibility, electrodischarge machining(E.D.M.) and toughness.Yet, preferably keep the crystallization carbide that reaches to a certain degree, because of when quenching, not making the particle alligatoring or be mingled with various particle size if having the crystallization carbide fully; The L value is more than or equal to 15.8 and be less than or equal to 20.8 better, is preferably more than or equal to 16.0 and is less than or equal to 20.5.

The crystallization carbide means the carbide that circular corresponding diameter (circle-corresponding diameter) surpasses about 10 μ m, mainly by M ₇C ₃Represent (M represents Cr, Mo etc.); 15.5 the L value to 21.0 is promptly corresponding to 0.20 to 4.0wt% crystallization carbide.

(3)0.60wt％＜Si≤2.0wt％

Because of Si is what to be added as the deoxidation element, so it is contained in the steel usually.In the present invention, initiatively add Si with assisted machining; Because of add soft (the about HRB 95) state after the obtainable improvement processibility of Si does not only betide annealing, also betide quench or tempering after high rigidity state (HRC 61 or bigger), interpolation Si also helps to improve high tempering hardness.

For obtaining this effect, must add the Si that surpasses 0.6wt% content, even add Si after amount, but that effect has reached is saturated, therefore, Si content preferably is set in 2.0wt% or lower; Silicone content is 0.65wt% or bigger and 1.8wt% or littler preferable again, if 0.7wt% or bigger and 1.5wt% or littler then better.

(4)0.10wt％≤Mn≤1.0wt％

Mn has increases hardenability to promote the effectiveness of hardness and intensity, and itself and high speed cutting element S are reacted, and forms inclusion compound (inclusion) thus to improve cutting character effectively.For obtaining this effect, required Mn addition is 0.10wt% or more; When excessive interpolation Mn, promptly destroyed hot workability, therefore, Mn content is preferably 1.0wt% or lower.

(5)0.03wt％≤S≤0.2wt％

S is a high speed cutting element, it can improve processibility to form inclusion compound with the Mn bond, because of adding soft (the about HRB 95) state after the obtainable improvement processibility of S does not only betide annealing, also betide the high rigidity state (HRC 61 or bigger) after quenching or the tempering.

For obtaining this effect, must add the S of 0.03wt% or more content, when excessive interpolations S, looking into than impact (Charpy impact) value in the material block will significantly decay, and therefore, Si content preferably is set in 0.2wt% or lower.

(6)1.25wt％＜Mo+0.5W＜3.0wt％

Mo and W form carbide, carry out tempered secondary hardening amount to be increased under 450 ℃ or the higher temperature.Though Mo and W have same effect,, need double W amount, so Mo and W content are to be adjusted by the described Mo equivalent of Mo+0.5W for having the effect that equates with Mo.

Behind quenching and tempering, for obtaining HRC 61 or bigger hardness, the Mo equivalent must be greater than 1.25wt%; Yet, when the Mo equivalent is excessive, hot workability, toughness, and processibility promptly show and worsen, therefore, the Mo equivalent is preferably less than 3.0wt%.

(7)0.05wt％≤V≤1.0wt％

V-arrangement becomes stable carbide to prevent the particle alligatoring effectively, and it also helps to improve wear resistant and hardness by forming carbide.For obtaining these effects, must add the V of 0.05wt% or more content, when the V too high levels, because of the increase military order processibility and the hot workability reduction of carbide amount, therefore, V content preferably is set in 1.0wt% or lower.

Except above-mentioned element, cold work tool steel of the present invention can more comprise following one or more elements, and the compositing range of each element and restriction reason will be described as follows.

(8)0.005wt％≤Se≤0.10wt％

(9)0.005wt％≤Te≤0.10wt％

(10)0.0002wt％≤Ca≤0.010wt％

(11)0.005wt％≤Pb≤0.10wt％

(12)0.005wt％≤Bi≤0.10wt％

Can add Se, Te, Ca, Pb and/or Bi to be to promote processibility, adds these elements and add Si and can't suppress improvement on the processibility.

In Mn-sulfide, Se and Te can be used as the substitute element of S; Ca can be by forming oxide compound or being dissolved in the Mn-sulfide, to form protective membrane man-hour on the cutting tool surface and to promote processibility in adding; Again, the Pb and the Bi fusion of the hot military order low melting material that processing is produced with aspire to producing lubricant effect between cutting tool and corner cut, promote processibility.

For obtaining this kind effect, the addition of above-mentioned element must be more than or equal to its lower value; Because of excessively adding the mechanical characteristics that these elements will destroy steel,, its addition is less than or equal to the above-mentioned upper limit so preferably being set in.

(13)0.01wt％≤Cu≤2.0wt％

(14)0.01wt％≤Ni≤2.0wt％

(15)0.20wt％≤Co≤1.0wt％

(16)0.0003wt％≤B≤0.010wt％

Cu, Ni, Co and B are dissolved in the matrix to promote hardenability effectively; Ni also has by reducing impact transfer (impact transition) temperature to increase toughness and to promote to avoid destroying the effect of weldability by toughness.In cold mould,, the situation that makes the local rising of die temperature because of processing heating (working-heating) is often arranged according to high-tensile steel or working conditions.Co has the effect of avoiding mould generation tension set by this temperature increase with the enhancement hot strength.For obtaining these effects, the addition of these elements preferably is set in more than or equal to above-mentioned lower value; Because of excessively adding the mechanical characteristics that these elements will destroy steel,, its addition is less than or equal to above-mentioned higher limit so preferably being set in.

(17)0.001wt％≤P≤0.030wt％

(18)0.0050wt％≤N≤0.050wt％

(19)0.001wt％≤Al≤0.10wt％

(20)0.0002wt％≤O≤0.010wt％

P, N, O are contained in the steel unavoidablely, and P is isolated from the granule boundary, and O forms oxide compound, and N forms nitride.In steel, Al and O or N reaction are to form oxide compound or nitride, and these elements can promote toughness by reducing its addition.For obtaining this effect, the addition of these elements preferably is set in and is less than or equal to above-mentioned higher limit; Preferably P accounts for 0.020wt% or still less, and N accounts for 0.030wt% or still less, and Al accounts for 0.050wt% or still less, and O accounts for 0.050wt% or still less.

The oxide compound of Al or nitride help to prevent the particle alligatoring, hereat if these constituent contents are excessively rare, and particle chap and destroy steel toughness on the contrary.For reducing these constituent contents, will increase manufacturing cost more than requirement; Again, when these elements reach or during less than some fixed value, promote the flexible effect and also reach saturatedly, therefore, the content of these elements preferably is set in more than or equal to above-mentioned lower value.

(21)0.010wt％≤Nb≤0.10wt％

(22)0.005wt％≤Ta≤0.10wt％

(23)0.005wt％≤Ti≤0.10wt％

(24)0.005wt％≤Zr≤0.10wt％

(25)0.005wt％≤Mg≤0.10wt％

(26)0.005wt％≤REM≤0.10wt％

Nb, Ta, Ti, Zr, each all can promote toughness effectively Mg and REM, Nb wherein, Ta, Ti, and Zr forms fine carbonitride and promotes toughness by fine particlesization; Mg and REM then promote toughness effectively by reducing the oxygen level in the matrix.

For obtaining these effects, the addition of these elements preferably is set in more than or equal to above-mentioned lower value; When addition is excessive, will destroy the toughness and the weldability of steel, so preferably being set in, its addition is less than or equal to above-mentioned higher limit.

Cold work tool steel of the present invention be by will having above-mentioned composition material in addition quenching and tempering get.When tempering temperature is low, the release deficiency of the unrelieved stress that when quenching, imports, so that destroyed electrodischarge machining(E.D.M.), therefore, tempering temperature preferably is set in more than or equal to 450 ℃.Because the alloy composition in the cold work tool steel of the present invention has been made optimization, so, also can have high rigidity (particularly, maximum hardness is more than or equal to HRC 61) even under more than or equal to 450 ℃ high temperature, implement tempering.

The particle diameter of old austenite (prior austenite) can influence toughness.Be the cold work tool steel that acquisition has high tenacity, preferably adopt the particle diameter of less old austenite; Yet, when particle diameter is too small, effect is promptly reduced to minimum, so certainly will increase cost, the particle diameter of old friend's austenite preferably is set to particle size Gq for more than or equal to 3.0 and be less than or equal to 8.0, " particle size Gq " means the grain size of cooled old austenite, and it is to utilize the method measurement described in the JIS G0551 to get.

The carbide that is comprised in the cold work tool steel such as has when preventing to quench at the effect of particle diameter alligatoring; Yet, because of the carbide content that sets among the present invention less (compared to known cold work tool steel SKD11 for example), so the easy alligatoring of particle diameter comparatively speaking.Therefore, for obtaining to have the high rigidity steel of suitable particle size Gq, need under proper temperature, implement quench treatment; Particularly, quenching temperature more preferably greater than or equal 950 ℃ and be less than or equal to 1080 ℃.When we when this temperature range is quenched, can avoid the particle diameter alligatoring.

Because the present invention tends to promote high speed cutting character by adding S basically, so A type inclusion can occur in a certain fixed range, " A type inclusion compound " means the inclusion compound that the inclusion compound estimation technique utilized described in the JIS G0555 decides, and it is mainly corresponding to sulfide.

For obtaining to have the cold work tool steel of excellent machining property, dA 60 * 400 is preferably in 0.10% to 1.50% scope; " dA 60 * 400 " mean the inclusion compound content of measuring according to the method described in the JIS G0555, and it is the inclusion compound content under observing with 400 power opticmicroscopes, 60 OV (visual angle); For further obtaining high working property, maximum length is that 20 μ m or littler A type inclusion compound preferably account for whole A type inclusion compound 30% ratio.

For forming this A type inclusion compound, the addition of Mn must be fit to S content, and Mn content (wt%) is minimum must be more than or equal to 1.7 times of S content (wt%); Because of also needing Mn to promote hardenability, so the addition of Mn is usually more than the Mn content (wt%) that is fit to S content (wt%).

Because of Type B inclusion compound and C type inclusion compound (aluminium, other oxide compound etc.) not only can hinder and improve high speed cutting character, also can destroy and look into than impact value, both preferably can reduce as far as possible; The inclusion compound that the inclusion compound estimation technique utilized described in the JIS G0555 of meaning Type B inclusion compound and C type inclusion compound decides.

Be the cold work tool steel that acquisition has excellent in machinability matter and shock-resistance, d (B+C) 60 * 400 particularly preferably is less than or equal to 0.05%; " d (B+C) 60 * 400 " means Type B and the C type inclusion compound content of measuring according to the method described in the JIS G0555, and it is the inclusion compound content under observing with 400 power opticmicroscopes, 60 OV (visual angle).

The effect of cold work tool steel of the present invention then will be described.Because the crystallization carbide has high rigidity, the wear resistant of cold work tool steel can improve by disperseing the mass crystallization carbide; Yet the mass crystallization carbide not only can destroy processibility, also can make the thread breakage in the line cutting electrodischarge machining(E.D.M.).The crystallization carbide is easy to become the initial point of fracture, because of its particle size bigger usually; On the other hand, the crystallization carbide is crossed the major general and is made hardness reduction, particle alligatoring, and toughness variation.

In cold work tool steel of the present invention, because of the amount of crystallization carbonization thing when the optimization L value reduces relatively, thus can promote processibility, and also can reduce the thread breakage problem in the line cutting electrodischarge machining(E.D.M.) for example; Moreover, reduced to minimumly because of the alligatoring crystallization carbide amount of the initial point that becomes fracture, and particle also becomes fine, so can reach high tenacity.

The K value is presented at the remaining Cr content in the matrix under the above-mentioned suitable quenching temperature, and necessary secondary hardening can be by reaching K value optimization.Si is a high speed cutting element, and it also helps to be lifted at the above hardness of tempering temperature; Again, the Mo equivalent can influence secondary hardening hardness.

Cold work tool steel of the present invention can be guaranteed the hardness more than or equal to HRC 61, and it is the prerequisite of cold work tool steel when quenching and tempering; Because except making K value optimization, other for example forms also optimization in addition of Si content and Mo equivalent.

Moreover because of can implementing high tempering, the unrelieved stress that is produced in material when quenching can discharge fully, therefore, except possess excellent machining property, even when electrodischarge machining(E.D.M.) or line cutting electrodischarge machining(E.D.M.), also can prevent the steel fracture or damage.

Again, material is easy to add forging welding in man-hour to the face of tool in high-speed range (high rotating speed), and therefore, instrument is being concatenated to form and separating and continue to denude because of forging welding part very easily.In cold work tool steel of the present invention,, be difficult for the forging welding situation takes place, and can suppress the abrasion of instrument because of the addition of Si is more than or equal to 0.6wt%; Therefore, can to possess more known shear steel be high workability to cold work tool steel.

Embodiment

To have that each elementary composition steel carries out fusion shown in the table 1 (embodiment 1 to 20 and comparing embodiment 1 to 10) in the high frequency vacuum melting furnace.To implement forge hot by the steel ingot bar that casting gets, to form the square bar of 35 * 55mm; After implementing forge hot, little by little cool off square bar with the rate of cooling of 7 ℃/hr from 880 ℃ and implement spheroidizing.

Table 1

	Numbering	??C	??Si	??Mn	??P	??S	??Cu	??Ni	??Cr	??Mo	??W	??V	??Al	??N	??O	The K value	The L value	Other
																			Embodiment	??1	??0.75	??0.91	??0.43	??-	??0.065	??-	??-	??6.75	??1.89	??0.02	??0.21	??-	??-	??-	??1.65	??18.375
??2	??0.76	??0.61	??0.55	??-	??0.085	??-	??-	??5.73	??1.25	??0.04	??0.23	??-	??-	??-	??0.562	??17.51
																		??3		??0.89	??0.65	??0.32	??-	??0.093	??-	??-	??6.73	??1.32	??-	??0.19	??-	??-	??-	??0.678	??20.525
??4	??0.90	??0.73	??0.38	??-	??0.134	??-	??-	??7.03	??1.33	??-	??0.17	??-	??-	??-	??0.91	??20.98
																		??5		??0.83	??0.83	??0.68	??-	??0.153	??-	??-	??8.03	??1.53	??-	??0.14	??-	??-	??-	??2.386	??20.895
??6	??0.73	??0.93	??0.83	??-	??0.194	??-	??-	??7.42	??1.73	??0.06	??0.11	??-	??-	??-	??2.456	??18.735
																		??7		??0.62	??1.03	??0.92	??-	??0.034	??-	??-	??6.64	??1.59	??-	??0.09	??-	??-	??-	??2.424	??16.25	??Se＝0.011
??8	??0.60	??1.12	??0.98	??-	??0.043	??-	??-	??6.21	??1.39	??-	??0.07	??-	??-	??-	??2.13	??15.51	??Ca＝0.0054
																		??9		??0.74	??1.32	??0.12	??-	??0.053	??-	??-	??6.43	??1.95	??-	??0.05	??-	??-	??-	??1.398	??17.9	??Pb＝0.007.Bi＝0.084
??10	??0.73	??1.53	??0.25	??-	??0.083	??-	??-	??7.39	??1.83	??0.11	??0.12	??-	??-	??-	??2.426	??18.705	??Te＝0.083
																		??11		??0.68	??1.73	??0.23	??-	??0.075	??0.09	??0.21	??6.33	??2.21	??-	??0.32	??-	??-	??-	??1.706	??16.87	??Co＝0.43
??12	??0.83	??1.83	??0.21	??-	??0.087	??0.03	??0.81	??6.78	??2.39	??0.31	??0.33	??-	??-	??-	??1.136	??19.645
																		??13		??0.79	??1.91	??0.53	??-	??0.093	??0.31	??0.08	??7.34	??2.57	??-	??0.36	??-	??-	??-	??1.968	??19.585	??Se＝0.031，B＝0.0007
??14	??0.66	??1.03	??0.22	??-	??0.063	??0.03	??0.23	??6.48	??2.85	??-	??0.41	??-	??-	??-	??1.992	??16.71
																		??15		??0.75	??0.95	??0.34	??0.007	??0.068	??0.11	??0.09	??6.11	??2.93	??-	??0.44	??0.011	??0.023	??0.0034	??1.01	??17.735	??Ca＝0.0049
??16	??0.79	??0.94	??0.41	??0.004	??0.068	??0.21	??0.39	??5.98	??2.71	??-	??0.67	??0.031	??0.011	??0.0023	??0.608	??18.225
																		??17		??0.81	??0.83	??0.53	??0.001	??0.073	??0.12	??0.11	??7.84	??2.13	??-	??0.78	??0.021	??0.008	??0.0053	??2.332	??20.395
??18	??0.83	??0.89	??0.44	??0.015	??0.041	??0.33	??0.04	??8.10	??2.31	??0.53	??0.83	??0.043	??0.005	??0.0084	??2.456	??20.965	??Mg＝0.084
																		??19		??0.85	??1.23	??0.38	??0.029	??0.051	??0.21	??0.08	??7.45	??2.09	??-	??0.92	??0.059	??0.038	??0.0004	??1.67	??20.625	??Nb＝0.09，Ta＝0.007，Zr＝0.09
??20	??0.74	??0.94	??0.39	??0.021	??0.073	??0.23	??0.13	??6.45	??1.89	??1.03	??0.81	??0.085	??0.045	??0.0013	??1.418	??17.92	??Ti＝0.006，REM＝0.084
																		Comparing embodiment		??1	??1.03	??0.94	??0.35	??0.013	??0.001	??0.21	??0.13	??8.31	??1.94	??1.53	??0.23	??0.003	??0.011	??0.0019	??1.306	??24.275
??2	??0.63	??0.73	??1.43	??-	??0.011	??-	??0.21	??6.53	??1.02	??-	??0.31	??-	??0.009	??-	??2.246	??16.295
																			??3	??0.69	??0.43	??0.43	??-	??0.045	??-	??-	??6.94	??0.34	??1.35	??0.21	??0.004	??0.1128	??-	??2.248	??17.635
??4	??0.75	??0.32	??0.13	??-	??0.073	??0.03	??-	??6.23	??0.86	??1.04	??0.01	??-	??-	??0.0001	??1.13	??17.855
																			??5	??0.71	??0.21	??0.23	??0.032	??0.063	??0.09	??0.31	??6.01	??0.95	??0.09	??0.02	??-	??0.034	??0.0083	??1.182	??17.015
??6	??1.35	??0.63	??0.45	??0.021	??0.001	??-	??-	??12.31	??1.93	??-	??1.35	??0.023	??-	??0.031	??3.13	??33.235
																			??7	??1.24	??0.93	??0.83	??0.011	??0.002	??0.34	??-	??11.83	??1.83	??0.35	??0.41	??-	??0.021	??-	??3.398	??31.05
??8	??1.11	??1.32	??0.03	??-	??0.002	??-	??0.02	??10.84	??2.01	??-	??0.24	??0.169	??-	??0.0005	??3.292	??28.045
																			??9	??1.04	??0.85	??0.29	??0.019	??0.008	??0.22	??-	??8.83	??1.67	??0.46	??0.27	??-	??-	??0.0142	??1.758	??24.95
??10	??1.03	??0.32	??0.63	??-	??0.103	??-	??-	??7.34	??1.23	??0.19	??0.33	??0.034	??-	??-	??0.336	??23.305

Each is elementary composition to be (wt%) to represent with " weight percent "; K value and L value are also identical.

The steel product of each generation all is subject to processing property testing (end mill processing test), line cuts electrodischarge machining(E.D.M.) test, hardness estimation, looks into than impacting test, quenching back particle size Gq and the estimation of inclusion compound content.

Processibility test (end mill processing test) is to implement a testing plate that cuts down from steel product at the Spheroidizing Annealing state.Test condition is as follows:

Instrument: sintered carbide (cemented carbide) M 20 (φ 32mm)

Speed: 200m/min

Feed-in speed: 0.15mm/rev

Width of cut: 4.5mm

Cutting level: 1.2mm

Machining oil: do not have

Life tools: the cutting distance when the maximum wear loss of cutter flank portion reaches 0.3mm

Method of estimation: with life tools of No. 1, compare tool steel as 100 relative estimation

The test of line cutting electrodischarge machining(E.D.M.) is not implement suddenly according to following.The letter speech, cut out one 30 * 50 * 200mm testing plate from the Spheroidizing Annealing steel, testing plate is quenched under a predetermined condition and tempering; After getting out the hole of φ 4mm on this testing plate, testing plate promptly utilizes line cutting electrodischarge machining(E.D.M.) to cut a hole into the square shape of 10 * 20mm; After implementing electrodischarge machining(E.D.M.), make testing plate erect one day, measure the crack number that is produced on the testing plate.

Aspect hardness, cut out the sheet testing plate of one 20 * 20mm from the Spheroidizing Annealing steel, the hardness after measuring quenching and tempering under the preset temperature; Measurement tempered numerical value (tested for hardness) and in 100 to 600 ℃ of following tempered maximum values (maximum hardness) under the specified temp shown in the table 2.

At room temperature, to behind quenching and tempering under the preset temperature and form to look into than impacting testing plate from the 10R-of Spheroidizing Annealing steel nick shaped and implement and look into than impacting test, the mean value of getting three testing plate is as impact value.

Particle size Gq measures according to the method described in the JIS G0551.A type inclusion compound and (B+C) the inclusion compound content of type inclusion compound be utilize the method described in the JIS G0555 measure (the opticmicroscope enlargement ratio: 400, visual angle number: 60).

Table 2 shows quenching temperature, tempering temperature and the various different result who estimates test, and the pass between L value and crystallization carbide amount is then to be shown in Fig. 1.

Table 2

	Numbering	Quenching temperature (℃)	Tempering temperature (℃)	Highest hardness (HRC)	Tested for hardness (HRC)	Processibility	Line cutting electrodischarge machining(E.D.M.)	Look into and compare impact value	Particle size (Gq)	Inclusion compound content dA	Inclusion compound content d (B+C)
												Embodiment	??1	??1020	??500	??62.8	??61.3	??187	Good	??33	??6.7	??0.23	??0.002
??2	??1015	??520	??63.3	??62.1	??175	Good	??35	??7.8	??0.85	??0.001
											??3		??1010	??490	??64.3	??63.1	??189	Good	??31	??5.5	??0.41	??0
??4	??1000	??450	??61.8	??61.8	??248	Good	??39	??5.7	??1.23	??0.004
											??5		??990	??470	??62.2	??62.1	??283	Good	??34	??6.3	??0.93	??0.003
??6	??1030	??530	??61.1	??61.1	??344	Good	??32	??4.3	??1.13	??0
											??7		??1020	??480	??63.3	??62.2	??164	Good	??41	??4.8	??0.11	??0.004
??8	??1035	??490	??62.8	??62.2	??186	Good	??41	??5.8	??0.29	??0.001
											??9		??1045	??500	??63.3	??61.1	??222	Good	??35	??4.9	??0.28	??0.008
??10	??1050	??510	??62.2	??61.2	??283	Good	??32	??7.9	??0.75	??0.003
											??11		??1020	??500	??63.9	??61.2	??297	Good	??31	??6.8	??0.38	??0
??12	??1025	??500	??64.9	??61.3	??324	Good	??35	??3.4	??0.63	??0
											??13		??1015	??510	??64.7	??62.2	??340	Good	??34	??3.9	??0.53	??0.002
??14	??1010	??520	??64.1	??62.4	??199	Good	??45	??4.5	??0.35	??0
											??15		??1015	??480	??63.1	??62.1	??195	Good	??49	??4.1	??0.45	??0
??16	??1020	??500	??61.1	??61.1	??194	Good	??41	??5.9	??0.43	??0
											??17		??1030	??460	??62.3	??62.2	??187	Good	??47	??6.3	??0.36	??0.002
??18	??1030	??530	??63.8	??61.9	??156	Good	??47	??6.8	??0.42	??0.004
											??19		??1030	??480	??63.3	??61.8	??208	Good	??38	??5.2	??0.26	??0.005
??20	??1025	??550	??62.1	??62.1	??200	Good	??37	??6.9	??0.73	??0.007
											Comparing embodiment		??1	??1035	??500	??63.3	??62.2	??100	Good	??12	??7.3	??0.004	??0.003
??2	??1030	??500	??59.3	??59.3	??123	Difference, soft	??33	??7.4	??0.002	??0.004
												??3	??1020	??250	??61.1	??61.1	??133	Difference, fracture	??32	??4.8	??0.25	??0.13
??4	??1020	??500	??57.3	??57.3	??114	Difference, soft	??34	??5.3	??0.36	??0
												??5	??1010	??490	??56.7	??56.7	??143	Difference, soft	??39	??5.6	??0.31	??0.001
??6	??1020	??490	??63.9	??59.3	??69	Difference, soft	??11	??4.9	??0.007	??0.13
												??7	??1015	??480	??63.3	??59.2	??83	Difference, thread breakage	??9	??6.3	??0.012	??0
??8	??1150	??510	??62.7	??58.4	??65	Difference, thread breakage	??12	??0.5	??0.019	??0
												??9	??1030	??200	??61.8	??61.7	??95	Difference, fracture	??11	??5.7	??0.04	??0.35
??10	??1030	??180	??62.1	??62.1	??103	Difference, fracture	??9	??6.3	??0.75	??0.003

As shown in Figure 1, having a pass between L value and the crystallization carbide amount is formula, and when the L value surpassed 21.0, crystallization carbide amount then surpassed 4.0wt%.In comparing embodiment 1 and 6～10, the L value of each embodiment is all very big, so crystallization carbide amount is many, therefore, the low and poor in processability of the impact value of steel; Comparing embodiment 7 and 8 particularly, line cutting electrodischarge machining(E.D.M.) promptly causes thread breakage; In comparing embodiment 3,9 and 10,, just produce fracture after the electrodischarge machining(E.D.M.) because of tempering temperature is lower than 450 ℃; Moreover in comparing embodiment 2,4 and 5, its highest hardness is less than HRC 61, and because of alloying element Mn, Mo reaches V not within the scope of the invention; In comparing embodiment 6, can't reach abundant secondary hardening because of the K value is excessive, and highest hardness is less than HRC 61.

Anti-, each all possesses highest hardness more than or equal to HRC 61 steel of the present invention (embodiment) 1～20, because each amount of element (wt%) of K value, L value and other alloying element is optimization all, so it demonstrates the HI high impact value with excellent machining property and electrodischarge machining(E.D.M.).

Fig. 2 shows that the pass between Si addition and processibility is, wherein accounts for 0.6wt% or more for a long time when Si content, and visible processibility significantly promotes, and reason is because the instrument abrasion due to the forging welding is suppressed because of the Si that adds a predetermined amount.

Preferred embodiment of the present invention is described in more detail in; Yet the present invention only limits to the foregoing description absolutely not, is not departing under the purport of the present invention, and the present invention can do various variation.

Cold work tool steel of the present invention can be used as various cold-work die and various cold set.

Claims (30)

1. cold work tool steel comprises:

≤ K value≤2.6 0.4 (K value=Cr (wt%)-6.8C (wt%));

≤ L value≤21.0 15.5 (L value=Cr (wt%)+15.5C (wt%));

0.60wt％＜Si≤2.0wt％；

0.10wt％≤Mn≤1.0wt％；

0.03wt％＜S≤0.2wt％；

1.25wt％＜Mo+0.5W＜3.0wt％；

0.05wt%≤V≤1.0wt%; And

Remainder Fe and inevasible impurity;

Wherein the highest hardness by the back tempering gained under 450 ℃ or higher temperature that quenches is HRC 61 or bigger value.

2. cold work tool steel as claimed in claim 1 more comprises one or more selections from following conditions of elements:

0.005wt％≤Se≤0.10wt％；

0.005wt％≤Te≤0.10wt％；

0.0002wt％≤Ca≤0.010wt％；

0.005wt%≤Pb≤0.10wt%; And

0.005wt％≤Bi≤0.10wt％。

3. cold work tool steel as claimed in claim 1 more comprises one or more selections from following conditions of elements:

0.01wt％≤Cu≤2.0wt％；

0.01wt％≤Ni≤2.0wt％；

0.20wt%≤Co≤1.0wt%; And

0.0003wt％≤B≤0.010wt％。

4. cold work tool steel as claimed in claim 2 more comprises one or more selections from following conditions of elements:

0.01wt％≤Cu≤2.0wt％；

0.01wt％≤Ni≤2.0wt％；

0.20wt%≤Co≤1.0wt%; And

0.0003wt％≤B≤0.010wt％。

5. cold work tool steel as claimed in claim 1 more comprises one or more selections from following conditions of elements:

0.0010wt％≤P≤0.030wt％；

0.0050wt％≤N≤0.050wt％；

0.0010wt%≤Al≤0.10wt%; And

0.0002wt％≤O≤0.010wt％。

6. cold work tool steel as claimed in claim 3 more comprises one or more selections from following conditions of elements:

0.0010wt％≤P≤0.030wt％；

0.0050wt％≤N≤0.050wt％；

0.0010wt%≤Al≤0.10wt%; And

0.0002wt％≤O≤0.010wt％。

7. cold work tool steel as claimed in claim 4 more comprises one or more selections from following conditions of elements:

0.0010wt％≤P≤0.030wt％；

0.0050wt％≤N≤0.050wt％；

0.0010wt%≤Al≤0.10wt%; And

0.0002wt％≤O≤0.010wt％。

8. cold work tool steel as claimed in claim 6 more comprises one or more selections from following conditions of elements:

0.010wt％≤Nb≤0.10wt％；

0.005wt％≤Ta≤0.10wt％；

0.005wt％≤Ti≤0.10wt％；

0.005wt％≤Zr≤0.10wt％；

0.005wt%≤Mg≤0.10wt%; And

0.005wt％≤REM≤0.10wt％。

9. cold work tool steel as claimed in claim 7 more comprises one or more selections from following conditions of elements:

0.010wt％≤Nb≤0.10wt％；

0.005wt％≤Ta≤0.10wt％；

0.005wt％≤Ti≤0.10wt％；

0.005wt％≤Zr≤0.10wt％；

0.005wt%≤Mg≤0.10wt%; And

0.005wt％≤REM≤0.10wt％。

10. cold work tool steel as claimed in claim 1, it has 0.10%≤dA 60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

11. cold work tool steel as claimed in claim 2, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

12. cold work tool steel as claimed in claim 3, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

13. cold work tool steel as claimed in claim 5, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

14. cold work tool steel as claimed in claim 6, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

15. cold work tool steel as claimed in claim 7, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

16. cold work tool steel as claimed in claim 9, it has 0.10%≤dA60 * 400≤1.50%, wherein " dA60 * 400 " inclusion compound content for measuring according to the method described in the JIS G0555.

17. cold work tool steel as claimed in claim 1, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

18. cold work tool steel as claimed in claim 2, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

19. cold work tool steel as claimed in claim 3, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

20. cold work tool steel as claimed in claim 5, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

21. cold work tool steel as claim 10, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

22. cold work tool steel as claim 11, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

23. cold work tool steel as claimed in claim 6, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

24. cold work tool steel as claim 12, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

25. cold work tool steel as claim 13, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

26. cold work tool steel as claimed in claim 7, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

27., more comprise one or more selections from following conditions of elements as the cold work tool steel of claim 22:

0.01wt％≤Cu≤2.0wt％；

0.01wt％≤Ni≤2.0wt％；

0.20wt%≤Co≤1.0wt%; And

0.0003wt％≤B≤0.010wt％。

28. cold work tool steel as claim 14, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

29. cold work tool steel as claim 15, can be by more than or equal to 950 ℃ and be less than or equal under 1080 ℃ the temperature and quench, and 3.0≤Gq≤8.0 obtain, and wherein Gq is the particle size of the old austenite after quenching, and it is to measure according to the method described in the JIS G0551.

30., more comprise one or more selections from following conditions of elements as the cold work tool steel of claim 28:

0.010wt％≤Nb≤0.10wt％；

0.005wt％≤Ta≤0.10wt％；

0.005wt％≤Ti≤0.10wt％；

0.005wt％≤Zr≤0.10wt％；

0.005wt%≤Mg≤0.10wt%; And

0.005wt％≤REM≤0.10wt％。