CN106435101A

CN106435101A - Small-specification 40Cr2SiMnMoV forging thermal treatment process

Info

Publication number: CN106435101A
Application number: CN201611002026.5A
Authority: CN
Inventors: 赵颖; 赵玉; 李亚平
Original assignee: Zhongyuan Special Steel Co Ltd
Current assignee: Zhongyuan Special Steel Co Ltd
Priority date: 2016-11-15
Filing date: 2016-11-15
Publication date: 2017-02-22

Abstract

The invention relates to a small-specification 40Cr2SiMnMoV forging thermal treatment process of hot-work die steel. The thermal treatment process includes following steps: 1, quenching and heating: preheating twice in the process of heating; 2, quenching and cooling: adopting an air-water-air-water-air-water spaced cooling mode; 3, tempering: transferring workpieces after surface temperature is cooled to about 250 DEG C into a prepared tempering furnace with furnace temperature of 200-300 DEG C, holding the temperature for 2h, heating at high temperature of 600-660 DEG C, and holding the temperature at a speed of 2-2.3h/100mm; 4, tempering and cooling: air cooling to room temperature; 5, repeatedly tempering. By the thermal treatment process, the defect that the prior art causes serious environment pollution and has potential fire hazards is overcome; by changing a quenching medium, high comprehensive mechanical performance of a material is ensured, production environment is improved effectively, and potential safety hazards are eliminated.

Description

Small dimension 40Cr2SiMnMoV forging Technology for Heating Processing

Technical field

The invention belongs to the production technical field of mould steel, particularly to a kind of small dimension of hot die steel 40Cr2SiMnMoV forging Technology for Heating Processing.

Background technology

Hot die steel carries out hot formed mould production mainly for the manufacture of to the metal of the condition of high temperature, and it is in high temperature shape In state metal heat forming processes, use environment is extremely severe, and surface of the work iterative cycles will make in the state of high temperature and chilling With, thus big and the stretching of complexity, compression contact stress and high-speed circulating high temperature cool-hot fatigue stress will be born.Mainly scrap Defect is the crackle that the scuffing on surface checking, ring crack and axis causes, and this is to be led to by many factors comprehensive function.Carry Its service life high only ensures, its core technology is ultra-clean steel by the strength degree and impact flexibility improving material Smelt, forge and Technology for Heating Processing.40Cr2SiMnMoV is one of steel grade that recent year develops in hot die steel field, Its transverse impact toughness is poor, and because its quenching degree is higher, can only adopt the mode of production of oil quenching, environmental pollution during quenching cooling Larger and there is disaster hidden-trouble.

Content of the invention

Present invention aim to overcome that environmental pollution present in above-mentioned prior art is larger and there is lacking of disaster hidden-trouble Point and provide and a kind of be effectively improved life by changing hardening media while ensureing that material obtains higher comprehensive mechanical property Produce the Technology for Heating Processing of environment the small dimension 40Cr2SiMnMoV forging eliminating safe hidden trouble.

The technical scheme is that and be achieved in that：A kind of small dimension 40Cr2SiMnMoV forging Technology for Heating Processing, bag Include following operation：1. Quench heating, is preheated in heating process twice, and one time preheating temperature is 350～400 DEG C, insulation 2.5h, secondary preheating temperature is 600～650 DEG C, is incubated 2h；2. quenching cooling, the gap using sky-water-sky-water-sky-water is cold But mode, first the pre-coo time of in the air be controlled to 220～260S, initial water temperature control is made as 35～45 DEG C, during a water-cooled Between be 200～230S, secondary water cool time is 160～200S, and three water-cooled times are 100～150S；3. it is tempered, in workpiece table Face temperature proceeds to when being cooled to 250 DEG C about in the tempering furnace that the furnace temperature got ready is 200～300 DEG C, is incubated 2 h, then pass through 600～660 DEG C of high-temperature heatings, and keep by 2～2.3 h/100mm；4. tempering cooling, is air cooled to room temperature；5. repeat to be tempered, Retained austenite is promoted to decompose, it is to avoid workpiece becomes fragile in use and size changes.

The good effect that technical scheme produces is as follows：Technology for Heating Processing is carried out using quenched mode.Quenching adds Control preheating temperature and firing rate when hot, reduce thermal stress.Using the gap of sky-water-sky-water-sky-water during quenching cooling The type of cooling, controls initially aerial pre-coo time and initial water temperature, strong ensureing that workpiece obtains quenching cooling enough While degree obtains martensitic structure, reduce quenching stress to greatest extent, it is to avoid stress is excessive to cause workpiece to ftracture.Strict control System is tempered the temperature and time keeping the stage into low temperature during stove, effectively reduces residual austenite content, promotes it to be changed into geneva Body is organized, then passes through high-temperature heating and holding, makes structural transformation completely, eliminates quenching stress, obtains the tempering rope of fine uniform Family name's body, obtains higher impact flexibility while ensureing high intensity.

Brief description

Fig. 1 is the flow chart of small dimension 40Cr2SiMnMoV forging Technology for Heating Processing of the present invention.

Specific embodiment

Small dimension 40Cr2SiMnMoV forging Technology for Heating Processing, is 40Cr2SiMnMoV hot die steel, C=from steel grade 0.35 ~ 0.45%, Si=0.80 ~ 1.10%, Mn=0.80 ~ 1.10%, Cr=1.54 ~ 2.00%, Mo=0.40 ~ 0.60%, V=0.20 ~ 0.40%, S≤0.010%, P≤0.015%, the bar of a diameter of φ 215mm.

This Technology for Heating Processing, including following operation：

1. Quench heating；Because this steel alloy element is many, heat conductivity is low, if carrying out high temperature shove charge and quick heating, certainly will make steel The larger temperature difference of inside and outside generation, causes very big internal stress, remove therefore during Quench heating strict control charging temperature≤ 350 DEG C outer, also needs to be preheated twice, and one time preheating temperature is 350～400 DEG C, is incubated 2.5h, and secondary preheating temperature is 600 ～650 DEG C, it is incubated 2h；Reduce, by preheating twice, the thermal stress producing in heating process, make workpiece internal and external temperature uniformly, simultaneously Be conducive to improving the firing rate of high-temperature region, promote crystal grain refinement.

2. quenching cooling, hardening heat adopts 860-880 DEG C, and temperature retention time typically adopts 1～1.2h/100mm, makes work Part center portion reaches set point of temperature, completes austenite transformation, is then carried out using the gap type of cooling of sky-water-sky-water-sky-water Cooling, the pre-coo time of in the air is 220～260S first, and a water-cooled time is 200～230S, and secondary air cooling time is 100～160S, secondary water cool time is 160～200S, and three air cooling times are 100～160S, three water-cooled time is 100～ 150S, initial water temperature is 35～45 DEG C.Cooled down by three gaps, make workpiece obtain quenching cooling earthquake intensity enough and obtain martensite While tissue, also can reduce quenching stress to greatest extent, it is to avoid stress is excessive to cause workpiece to ftracture.

3. it is tempered；Proceeding to the furnace temperature got ready when workpiece surface temperature is cooled to 250 DEG C about is 200～300 DEG C In tempering furnace, it is incubated 2 h, effectively reduce residual austenite content, promote it to be changed into martensitic structure, then it is warming up to 600～ 660 DEG C carry out high tempering, and temperature retention time typically adopts 2～2.3 h/100mm, carries out martensite decomposition and retained austenite Continuation change, obtain fine uniform tempered sorbite tissue, obtain higher comprehensive mechanical property.

4. tempering cooling, is air cooled to room temperature.

5. repeat operation 3. in tempering, promote retained austenite to decompose further, it is to avoid workpiece is from now on using process In become fragile and size change.

The more conventional oil of small dimension 40Cr2SiMnMoV hot-work die steel forgings tensile strength being produced using present invention process Quench and can improve 8% about, ballistic work can improve 30% about by more conventional oil quenching, be effectively improved production environment simultaneously and eliminate hidden safely Suffer from.Mechanics properties testing data sees attached list 1.

Subordinate list 1- mechanical property detects table

Claims

1. a kind of small dimension 40Cr2SiMnMoV forging Technology for Heating Processing it is characterised in that：This technique includes following operation：

1. Quench heating, is preheated in heating process twice, and one time preheating temperature is 350～400 DEG C, insulation 2.5h, and two Secondary preheating temperature is 600～650 DEG C, is incubated 2h；

2. quenching cooling, using the gap type of cooling of sky-water-sky-water-sky-water, the pre-coo time of in the air is controlled to first 220～260S, initial water temperature control is made as 35～45 DEG C, and water-cooled time is 200～230S, and secondary water cool time is 160～ 200S, three water-cooled times are 100～150S；

3. it is tempered, proceed to the tempering that the furnace temperature got ready is 200～300 DEG C when workpiece surface temperature is cooled to 250 DEG C about In stove, it is incubated 2 h, then passes through 600～660 DEG C of high-temperature heatings, and keep by 2～2.3 h/100mm；

4. tempering cooling, is air cooled to room temperature；

5. repeat 3. to be tempered, promote retained austenite to decompose, it is to avoid workpiece becomes fragile in use and size changes.