CN101182619A - High-strength toughness cold working die steel and method of producing the same - Google Patents

Abstract

The invention relates to a high-strength and tenacity cold die steel and a prepare method hereof; the invention belongs to the alloy steel prepare process and technology field. The chemical components with the corresponding weight percents of the invention are: 0.9 percent to 1.0 percent of C, 9 percent to 10 percent of Cr, 2.0 percent of Mo, 0.8 percent to 1.0 percent of V, 1.0 percent of Si, the weight percent of P which is less than 0.02 percent, the weight percent of S which is less than 0.02 percent and the rest is Fe. The prepare process and steps of the cold die steel of the invention are as follows: melting, electro-slag re-melting, annealing, rough forge, re-annealing, spheroidized annealing and quench tempering. The rigidity of the alloy steel prepared according to the method of the invention can reach 61 to 63HRC and the ballistic work AK can reach 61 to 85 J, which increase by more than three times against that of the original Cr12MoV steel.

Description

High-strength toughness cold working die steel and preparation method thereof

Technical field

The present invention relates to a kind of high-strength toughness cold working die steel and preparation method thereof, belong to the steel alloy manufacturing process technology field.

Background technology

Because the cold-work die steel chemical composition is of a great variety, wherein in the high chromium steel with the increasing of carbon content, the ununiformity of its eutectic carbides also strengthens, and causes the toughness of steel to descend.

As present existing Cr12MoV steel:

(1) composition of Cr12MoV is as shown in the table:

The chemical component table of Cr12MoV

C	Si	S	P	Mn	Ni	Cr	Mo	V
									1.59	0.35	0.00004	0.0137	0.299	0.08	12.04	0.49	0.29

(2) performance of Cr12MoV: have high rigidity and high-wearing feature, impelling strength is low.

(3) weak point of Cr12MoV: banded carbide makes the mechanical property of steel and physicals tangible anisotropy occur, and impelling strength reduces.Inhomogeneous grindability and the abrasive property variation that makes steel of distribution of carbides, the proneness that quenching crack forms increases.

Summary of the invention

The new steel grade that the purpose of this invention is to provide a kind of cold-work die steel designs new composition, and main design concept is for suitably reducing carbon amount and chromium amount, increase the content of molybdenum and vanadium, reducing also refining eutectic carbide, crystal grain thinning, to improve toughness.

A kind of high-strength toughness cold working die steel of the present invention is characterized in that having following chemical constitution and weight percent:

C 0.9～1.0％， Cr 9～10％，

Mo 2.0％， V 0.8～1.0％，

Si 1.0％， P ＜0.02％，

S＜0.02%, the Fe surplus.

The preparation method of above-mentioned high-strength toughness cold working die steel is characterized in that having following technological process and step:

A. melting: by traditional ordinary method melting; To be positioned in medium-frequency induction furnace or the electric arc furnace by the admixtion that above-mentioned prescription weighing cooperates, carry out melting more than the temperature, pour into a mould steel ingot then at 1500 ℃;

B. esr: above-mentioned steel ingot is put in the esr device as consumable electrode, carries out two refinings; Utilize electric current to melt consumable electrode steel alloy mother metal by the electroslag layer heat that has a resistance, liquid metal is frozen into steel ingot more again with in the metal pool in the water-cooled crystallization of molten drop form below the slag blanket of slag bath falls to; Steel ingot is progressively crystallization from bottom to top;

C. annealing: above-mentioned steel ingot under 830 ℃ of temperature, was annealed 8 hours, subsequently furnace cooling;

D. forge: more above-mentioned steel ingot is heated to 1200～1230 ℃, carries out rough forge, 940 ℃ of final forging temperatures obtain steel forgings;

E. annealing again: above-mentioned steel forgings is annealed once more, and annealing is 8 hours under 830 ℃ of temperature, subsequently furnace cooling;

F. nodularization is degenerated: with above-mentioned steel ingot 830 ℃ of insulations 3 hours, according to so that per hour 30 ℃ speed of cooling stove is cold; When the temperature cooling is made 730 ℃, be incubated 4 hours; Then so that per hour 30 ℃ speed of cooling stove is cold; It is cold that temperature reaches 550 ℃ of laggard line spaces;

G. Q-tempering: adopt high high the returning or the low mode of quenching and hanging down back of quenching; Height is quenched, and high to return technology mode be 1060 ℃～1080 ℃ quenchings, 520～540 ℃ of double temperings, each tempering 1 hour; Low quench that to hang down back technology mode be 1020～1040 ℃ of quenchings, 180～210 ℃ of tempering 1 hour; Finally make high-strength toughness cold working die steel.

Characteristics of the present invention and advantage are as described below: the inventive method has adopted electroslag remelting process, this is a secondary refining technology, adopt electroslag remelting process can reduce the content of air inclusions in the steel ingot, so deoxidation and desulfurization effectively, and can control and solidify, improve the both macro and micro tissue of remelting steel ingot, thus electroslag remelting process can obtain composition evenly, dense structure, superior in quality steel ingot.

The present invention has promptly adopted suitable annealing schedule and has adopted high high the returning or the low mode of quenching and hanging down back of quenching owing to adopted rational heat treatment technology, and the hardness performance of steel ingot and shock-resistant function are all improved a lot.

Description of drawings

Fig. 1 is present embodiment sample (SDC99) and hardness and the impelling strength comparison diagram of other control sample under+540 ℃ of tempering heat treatment conditions of 1080 ℃ of quenchings.

Fig. 2 is present embodiment sample (SDC99) and hardness and the impelling strength comparison diagram of other control sample under+210 ℃ of tempering heat treatment conditions of 1040 ℃ of quenchings.

Embodiment

After now specific embodiments of the invention being described in.

Embodiment 1: in the present embodiment, adopt the chemical constitution and the weight percent of steel alloy as follows:

C 0.95%, and Cr 9.5%, and Mo 2.0%, and V 1.0%, and Si 1.0%, P＜0.02%, S＜0.02%, Fe surplus.

The preparation process and the step of present embodiment Medium Alloy Steel are as follows:

(a) melting: after alloy is pressed the mentioned component design, by traditional ordinary method melting, will be positioned in medium-frequency induction furnace or the electric arc furnace by the alloy furnace charge that above-mentioned prescription comes, carry out melting more than the temperature at 1500 ℃, pour into a mould steel ingot then, it is stand-by to enter next step;

(b) esr: utilize electric current to melt the steel alloy mother metal of consumable electrode by the electroslag layer heat that has a resistance, in slag bath fell to metal pool in the water-cooled crystallization, steel ingot is progressively crystallization from bottom to top with the molten drop form for liquid metal.The content of gas and inclusion be can reduce behind the esr, and uniform ingredients, dense structure, steel ingot that quality is high obtained.Alloy obtains further refining during remelting, and inclusion removal is to float by wash heat with in the molten bath.The enduring quality and the plasticity of alloy all are improved, and eliminate or have alleviated various macroscopic microscopic defects;

(c) annealing: under 830 ℃ of temperature, annealed 8 hours, subsequently furnace cooling;

(d) forge: more above-mentioned steel ingot is heated to 1200～1230 ℃, carries out rough forge, 940 ℃ of final forging temperatures obtain steel forgings;

(e) annealing: under 830 ℃ of temperature, annealed 8 hours, subsequently furnace cooling;

(f) nodularization is degenerated: 830 ℃ of insulations 3 hours, according to so that per hour 30 ℃ speed of cooling stove is cold; When the temperature cooling is made 730 ℃, be incubated 4 hours; Then so that per hour 30 ℃ speed of cooling stove is cold; It is cold that temperature reaches 550 ℃ of laggard line spaces;

(g) adopt low quenching hang down back or quench height time of height: employing low quenched and hanged down back technology is 1040 ℃ of quenchings, 210 ℃ of tempering 1 hour; The height that adopts is quenched, and high to return technology be 1080 ℃ of quenchings, 540 ℃ of double temperings, each tempering each 1 hour.

Performance test

Sample (SDC99) to the foregoing description gained carries out the performance test of hardness and impelling strength.

Contrast steel grade its chemical constitution of sample and weight percent thereof are as follows:

The Cr12MoV steel:

The chemical component table of Cr12MoV

C	Si	S	P	Mn	Ni	Cr	Mo	V
									1.59	0.35	0.00004	0.0137	0.299	0.08	12.04	0.49	0.29

The SCD99 steel:

The chemical component table of SDC99

C	Si	S	P	Mn	Ni	Cr	Mo	V
									0.9462	1.0145	0.0017	0.0176	0.2747	0.1258	9.5643	1.9782	0.8825

The SCD3 steel:

The chemical component table of SDC3

C	Si	S	P	Mn	Ni	Cr	Mo	V
									0.9231	1.0084	0.0008	0.0143	0.2731	0.1189	9.5020	1.9410	0.8810

The Cr8 steel:

The chemical component table of Cr8

C	Si	S	P	Mn	Ni	Cr	Mo	V	W
										0.98	1.19	0.00039	0.0159	0.26	0.11	8.03	2.09	2.22	0.90

The DC53 steel:

The chemical component table of DC53

C	Si	S	P	Mn	Ni	Cr	Mo	V
									0.9876	0.9804	0.0008	0.0170	0.2700	0.1214	8.0969	1.9891	0.2599

Test-results is referring to Fig. 1 and Fig. 2.

Fig. 1 is present embodiment sample (SDC99) and hardness and the impelling strength comparison diagram of other control sample under+540 ℃ of tempering heat treatment conditions of 1080 ℃ of quenchings.

Fig. 2 is present embodiment sample (SDC99) and hardness and the impelling strength comparison diagram of other control sample under+210 ℃ of tempering heat treatment conditions of 1040 ℃ of quenchings.

This steel drift of the present invention through 1040 ℃ quench+210 ℃ of tempering after, hardness is 61HRC, ballistic work Ak is 85J, ballistic work with under identical thermal treatment, the DC53 of same rigidity is suitable, compares with Cr12MoV, ballistic work improves more than 2 times.Through 1080 ℃ quench+540 ℃ of tempering after, hardness is 63HRC, ballistic work Ak is 61J, ballistic work with under identical thermal treatment, the DC53 of same rigidity is suitable, compares with Cr12MoV, ballistic work improves more than 3 times.

Claims (2)

1. high-strength toughness cold working die steel is characterized in that having following chemical constitution and weight percent:

C 0.9～1.0％， Cr 9～10％，

Mo 2.0％， V 0.8～1.0％，

Si 1.0％， P ＜0.02％，

S＜0.02%, the Fe surplus.

2. the preparation method of a high-strength toughness cold working die steel is characterized in that having following technological process and step:

A. melting: by traditional ordinary method melting; To be positioned in medium-frequency induction furnace or the electric arc furnace by the admixtion that above-mentioned prescription weighing cooperates, carry out melting more than the temperature, pour into a mould steel ingot then at 1500 ℃;

B. esr: above-mentioned steel ingot is put in the esr device as consumable electrode, carries out secondary refining; Utilize electric current to melt consumable electrode steel alloy mother metal by the electroslag layer heat that has a resistance, liquid metal is frozen into steel ingot more again with in the metal pool in the water-cooled crystallization of molten drop form below the slag blanket of slag bath falls to; Steel ingot is progressively crystallization from bottom to top;

C. annealing: above-mentioned steel ingot under 830 ℃ of temperature, was annealed 8 hours, subsequently furnace cooling;

D. forge: more above-mentioned steel ingot is heated to 1200～1230 ℃, carries out rough forge, 940 ℃ of final forging temperatures obtain steel forgings;

E. annealing again: above-mentioned steel forgings is annealed once more, and annealing is 8 hours under 830 ℃ of temperature, subsequently furnace cooling;

F. nodularization is degenerated: with above-mentioned steel ingot 830 ℃ of insulations 3 hours, according to so that per hour 30 ℃ speed of cooling stove is cold; When the temperature cooling is made 730 ℃, be incubated 4 hours; Then so that per hour 30 ℃ speed of cooling stove is cold; It is cold that temperature reaches 550 ℃ of laggard line spaces;

G. Q-tempering: adopt high high the returning or the low mode of quenching and hanging down back of quenching; Height is quenched, and high to return technology mode be 1060 ℃～1080 ℃ quenchings, 520～540 ℃ of double temperings, each tempering 1 hour; Low quench that to hang down back technology mode be 1020～1040 ℃ of quenchings, 180～210 ℃ of tempering 1 hour; Finally make high-strength toughness cold working die steel.

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