CN103421940A

CN103421940A - Technological method for AISI4140 and AISI 4340 constructional steel forged piece quenching and tempering through one-time thermal cycling

Info

Publication number: CN103421940A
Application number: CN2013103977979A
Authority: CN
Inventors: 王立新; 刘岩; 姚伟; 高全德; 孙振环; 田建宁; 薛正国
Original assignee: Zhongyuan Special Steel Co Ltd
Current assignee: Henan Zhongyuan Special Steel Equipment Manufacturing Co Ltd
Priority date: 2013-09-05
Filing date: 2013-09-05
Publication date: 2013-12-04
Anticipated expiration: 2033-09-05
Also published as: CN103421940B

Abstract

The invention belongs to the technical field of shaft forged piece manufacturing and particularly relates to a technological method for AISI4140 and AISI 4340 constructional steel forged piece quenching and tempering through one-time thermal cycling, wherein the technological method is used for quenching and tempering of large-size forged pieces through one-time thermal cycling, shortens the manufacturing period and reduces the manufacturing cost. The method comprises the following steps that firstly, temperature-control forging is conduced; secondly, post-forging annealing and quenching and tempering treatment are conducted through heat generated after forging. The technological method for AISI4140 and AISI 4340 constructional steel forged piece quenching and tempering through one-time thermal cycling has the advantages that by adoption of the technological method, the forging heat is used for following-up post-forging hydrogen diffusion annealing and quenching and tempering heat treatment, the objective that quenching and tempering treatment is completed through one-time thermal cycling is achieved, the mechanical property of the product generated after quenching and tempering treatment according to the technological method is comparable to that of a product generated after quenching and tempering treatment conducted after rough machining.

Description

A kind ofly utilize a thermal cycling to carry out modified processing method to AISI4140 and AISI4340 structure iron forging

Technical field

The invention belongs to forging shaft manufacturing technology field, particularly utilize a thermal cycling to carry out large specification forging modified, shorten the manufacturing cycle, reduce a kind of processing method of manufacturing cost.

Background technology

The large specification forging shaft of tradition carries out modified manufacturing process route and all adopts the forging postheat treatment, after roughing, carries out modified again.Not only the manufacturing cycle long, need through the thermal cycling more than secondary simultaneously, increase forging surface oxidation decarburizing tendency, manufacturing cost is high.Directly expanded hydrogen annealing+modifier treatment after the present invention forges, adopt a thermal cycling to carry out modified, not only can be reduced manufacturing cost, simultaneously can shortened process, its mechanical property can reach modified effect after roughing equally.

Summary of the invention

The object of the present invention is to provide and a kind ofly utilize a thermal cycling to carry out modified processing method to large specification framework steel forgings, its forging mechanical property can reach the modified effect of roughing forging equally, can shorten the production cycle simultaneously and reduce manufacturing cost.

The object of the present invention is achieved like this:

A kind ofly utilize a thermal cycling to carry out modified processing method to large specification framework steel forgings, comprise following step:

Step 1: forge and adopt temperature Control Forging

Deflection and the temperature of last moulding process forged in major control, controls mold temperature at 700～850 ℃, and deflection is controlled at 20～30%, at the AC3 Near The Critical Point higher than the steel recrystallization temperature, carries out temperature Control Forging, to avoid the critical strain amount; Under the condition simultaneously allowed at equipment, control deflection 20～30%, utilize dynamically fully recrystallize, low temperature aximal deformation value and forge after the technological measure such as fast cold, by deformation and the effective combination of phase transformation, realize multiple crystal grain thinning and improve tissue, its effect can reach the effect that Comparative Examples is forged rear normalizing, and low temperature moderate finite deformation amount, make forging heart section obtain Effective Compaction simultaneously.

Step 2: utilize the heat after forging to carry out forging rear annealing+modifier treatment

To expand hydrogen annealing and property heat treatment (modified) combination after forging, realize that a thermal cycling reaches traditional forging and adopts second heat to loop the effect of modifier treatment.Be chilled to soon 400～650 ℃ after forging, then near material critical point, (600～700 ℃) are treated the material insulation, after forging process for fuel completes by the gross, cross and be chilled to 300～400 ℃, by 1～2 hour/100mm, be incubated, impel heart section austenite to perlitic transformation, further improve and forge rear grain fineness number and eliminate thick lamellar pearlite, do tissue for follow-up quenching and prepare.Be warming up to modified quenching temperature, carry out modifier treatment thereafter; The quenching temperature of modifier treatment adopts 800～900 ℃, all, soaking time adopts 0.5～1.5 hour/100mm, make workpiece heart section reach specified temperature, complete austenitic transformation, adopt the water-cooling pattern of sky-water space during quench cooled, carry out deep-hardening cooling, replace traditional water quenching and oil-cooling, fully the excavated material potentiality.Intermittently air cooling-water-cooled is three times, and air cooling time is≤3min for the first time, and the water-cooled time is 6-20min, air cooling time is 4-5min for the second time, the water-cooled time is 4-10min, and air cooling time is 5-6min for the third time, and the water-cooled time is 3-5min, can avoid like this quenching defect caused under quenching stress and thermal stress effect, can the degree of depth excessively cold, fully the excavated material potentiality, carry out high tempering after quenching, make martensite decomposition, Transformation of Retained Austenite, thereby reach, slightly add modified effect.

The advantage of this invention is the enforcement by the technical program, utilize and forge heat, carry out expanding hydrogen annealing and modified thermal treatment after follow-up forging, realize the modifier treatment that a time thermal cycling completes forging, carry out modified mechanical property after the mechanical property of its modified rear product and roughing suitable.

The accompanying drawing explanation

Fig. 1 is for expanding the graphic representation of hydrogen+modifier treatment after forging.

The graphic representation that Fig. 2 is forging rear annealing.

Fig. 3 expands for after forging the graphic representation that carries out modifier treatment after hydrogen and roughing.

Embodiment

Embodiment 1

The AISI4140 forging that the delivery specification is Φ 500 * 5800, forging last fire, the distortion allowance of reserved 30～100mm, forging temperature is controlled at 700～800 ℃ and is pulled out operation, obtain desired shape and size, 450～550 ℃ to the forging surface of the rear air coolings of forging, so fed to boiler is incubated by 0.6～1.0h/100mm at 650 ± 50 ℃, hang lower air cooling or mist after insulation cold, be chilled to 300～400 ℃ of fed to boiler is incubated by 0.8～1.5h/100mm at this temperature, rise to 850 ± 50 ℃ after insulation, press at this temperature

0.6～1.0h/100mm carries out evenly, being incubated by 0.6～1.0h/100mm, the quenching of coming out of the stove after the insulation end adopts intermittently air cooling-water-cooling pattern to be quenched, then at 500 ± 50 ℃, and after all being incubated by 1.5～2.5h/100mm respectively, air cooling.

Embodiment 2

The AISI4340 forging that the delivery specification is Φ 400 * 5800, forging last fire, the distortion allowance of reserved 60～120mm, forging temperature is controlled at 750～850 ℃ and is pulled out operation, obtain desired shape and size, 500～550 ℃ to the forging surface of the rear air coolings of forging, so fed to boiler is incubated by 0.8～1.2h/100mm at 650 ± 50 ℃, hang lower air cooling or mist after insulation cold, be chilled to 300～400 ℃ of fed to boiler is incubated by 1.0～1.5h/100mm at this temperature, rise to 850 ± 50 ℃ after insulation, 0.8～1.2h/100mm carries out samming, by 0.8～1.2h/100mm, be incubated, the quenching of coming out of the stove after insulation finishes, adopt intermittently air cooling-water-cooling pattern to be quenched, then at 550 ± 50 ℃, after all being incubated by 2.0～2.5h/100mm respectively, air cooling.

Above-mentioned example is implemented rear mechanical property detected result in Table 1

Table 1 mechanical property detected result

Figure 2013103977979100002DEST_PATH_IMAGE001

Result from table 1, the present invention forges a thermal cycling of rear employing and is directly forged rear expansion hydrogen+modifier treatment, final mechanical property with forge after annealed, carry out modified contrast after roughing and see, its intensity is suitable, toughness is better than traditional carrying out modified performance after slightly adding, reduce forging oxidation and decarburization phenomenon that repeatedly thermal cycling causes simultaneously, save manufacturing cost, simultaneously shortened process and manufacturing cycle.

Claims

1. one kind is utilized a thermal cycling to carry out modified processing method to AISI4140 and AISI4340 structure iron forging, it is characterized in that: comprise following step:

Step 1: forge and adopt temperature Control Forging

Be controlled to the type temperature during forging and molding at 700～850 ℃, deflection is controlled at 20～30%, is conducive to so further crystal grain thinning, and simultaneously the low heart section that is conducive to of final forging temperature obtains maximum deflection and pulled out operation forging and molding;

Be chilled to soon 400～650 ℃ after forging, then be 600～700 ℃ and treated the material insulation near material critical point, after forging process for fuel completes by the gross, cross and be chilled to 300～400 ℃, be incubated by 1～2 hour/100mm, be conducive to like this impel heart section austenite to perlitic transformation, can further improve and forge rear grain fineness number and eliminate thick lamellar pearlite, do tissue for follow-up quenching and prepare, then be warming up to modified quenching temperature, carry out modifier treatment, the quenching temperature of modifier treatment adopts 800～900 ℃, all, soaking time adopts 0.5～1.5 hour/100mm, make workpiece heart section reach specified temperature, complete austenitic transformation, it is cooling that during quench cooled, the water-cooled of employing sky-water space is carried out deep-hardening, intermittently air cooling-water-cooled is three times, air cooling time is≤3min for the first time, the water-cooled time is 6-20min, air cooling time is 4-5min for the second time, the water-cooled time is 4-10min, air cooling time is 5-6min for the third time, the water-cooled time is 3-5min, carry out high tempering after quenching, make martensite decompose, Transformation of Retained Austenite, thereby reach and slightly add modified effect.