| Mould steel occupies a very important position in industry,among which Cr12 Mo V steel has high hardness,high strength and good wear resistance,and is widely used at home and abroad.Cr12 Mo V steels are used for cold work mould needs to have high hardness and high wear resistance and toughness,are used as hot-work mould also need to have red hardness,heat treatment process can not change the material composition on the basis of the material by changing the composition and content of internal organization get the required performance,but improper heat treatment technology is easy to cause premature failure.The traditional heat treatment method has blindness and long research and development cycle.The heat treatment numerical simulation technology based on multi-field coupling method breaks this bottleneck.However,there are few studies on the multi-field coupling of Cr12 Mo V steel,especially there are difficulties in the dissolution and precipitation of carbides.In this paper,the effects of quenching and tempering process on temperature,microstructure,hardness and stress of Cr12 Mo V steel were simulated by using finite element analysis software Deform-Mo module based on multi-field coupling.According to the critical point of Cr12 Mo V steel,the quenching temperature of 980?1150 ? was selected to study the microstructure and content of Cr12 Mo V steel at different quenching temperatures.The best secondary hardening process for obtaining red hardness of Cr12 Mo V steel was predicted and analyzed by studying the precipitation of carbides under the processes of 1100?1150 ? quenching +510?540 ?tempering,and tempering for one ? three times respectively.Through the simulation model,temperature,microstructure transformation content,stress,hardness and so on are interrelated,and the multi-field coupling is realized.The temperature field simulation shows that the temperature distribution is uniform during the heat treatment process,and due to the size effect,the external heating and cooling of the sample in the heating and cooling process are in accordance with the actual law,indicating that the temperature can be used to analyze the distribution law of the microstructure field and stress field.The microstructure and hardness simulation show that the quenched microstructure of Cr12 Mo V steel is martensite +residual austenite + undissolved carbide.Quenching temperature at 1020 ?1050 ? residual austenite content are 20 % ? 40 %,the content of undissolved carbide is about 12 %,hardness is about 62 HRC,1110 ? ? 1150 ? quenching,residual austenite content reaches 80 %?90 %,undissolved carbide about 9 %,Hardness of about 40 HRC,It conforms to the actual law that the content of residual austenite increases,the content of undissolved carbide decreases and the hardness decreases with the quenching temperature increasing.The tempering simulation shows that the residual austenite decomposed into martensite and secondary carbides precipitated in the martensite and residual austenite.The secondary carbide precipitates more after quenching at 1110?1130 ? +520 ? 530 ? tempering for three times,so the secondary hardening effect of Cr12 Mo V steel is better in this process range.The simulation of stress field shows that the distribution of stress is affected by temperature and microstructure field,and the thermal stress and microstructure stress at the edge are larger and the risk of deformation is greater.Validation of simulation results with the experimental and literature data shows that simulation Cr12 Mo V steel composition and content of organization,hardness distribution were in good agreement with the actual,based on the multi field coupling method has good organization,hardness prediction ability,the heat treatment process has good reappearance ability,can provide Cr12 Mo V steels with reasonable heat treatment process optimization scheme.This paper has 81 pictures,13 tables and 80 references. |
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