Study On Recrystallization And Microstructure Prediction Of Alloy Tool Steel 75Cr1 Based On CSP Process

75Cr1 steel is a kind of high-carbon alloy tool steel with high strength,hardness,quench-hardening ability as well as ultra-high abrasion resistance.It's mainly used to manufacture high-precision cutting blade and some small tools,such as ultra-thin row cutting blades,razors,and other mandrel.At present,more and more steel enterprises began to explore medium & high-carbon steel technology based on CSP process,because it can effectively relieve a series of defects cased by conventional process,including segregation,surface decarbonization,poor quality and other issues.Therefore,75Cr1 steel based on CSP process of WISCO is chosen as the research object in the paper.The influence of different parameters on recrystallization of 75Cr1 steel are studied by making single-pass and double-pass compression thermal simulation experiments,and a series of predictive models are established.Then the simulation software developed by research group are used to analyze the hot rolling microstructure evolution under different process parameters.The main conclusions of this investigate are as follows:(1)According to the stress-strain curves of single-pass compression test and original austenite phase diagram of 75Cr1 steel under different deformation temperature and strain rates,the effects of different parameters on dynamic recrystallization of75Cr1 steel are discussed.The results show that the dynamic recrystallization of 75Cr1 steel is easy to occur at high temperature and low strain rates.(2)According to the data of single pass compression test,the Z parameter equation of 75Cr1 steel is obtained,and the dynamic recrystallization critical strain model,kinetic equation of dynamic recrystallization,flow stress model of high temperature austenite area and dynamic recrystallization grain size model are also established.All of the models fit well.(3)According to the stress-strain cures of double-pass compression test of 75Cr1 steel under different temperature,deformation degree,and strain rates,the static recrystallization softening rates are obtained,then the the impacts of different deformation parameters on static recrystallization of 75Cr1 steel are investigated,and its kinetic model of static recrystallization is established.The results show that the increases of deformation temperature,deformation degree,strain rate and interval time are conducive to the occurrence of static recrystallization.(4)The hot rolling microstructure evolutions under different product sizes,slab grain sizes,finishing inlet temperature and redutions are analyzed by the simulation software developed by research group.The results show that the simulation results of the software follow the basic laws of static and dynamic recrystallization,and the resultsare in accordance with the actual production situation.This research is aimed at providing the theoretical basis to the setting and optimization of hot rolling process parameters of WISCO CSP and the microstructure prediction for the actual production.