Study On Dynamic Recrystallization Behavior And Microstructure Evolution Of HD Alloy Steel

With the rapid development of high-end metal products,especially in the development of power plant steel,the demand for high-precision HD alloy steel rings is increasingly urgent and extensive.This article to a factory production of high precision HD alloy steel as the research object,through the study of the process optimization of HD alloy steel,control the amount of area austenitic recrystallization for HD already produce alloy steel combined with the actual situation improved,so as to control the performance of the alloy to achieve more conform to the requirements of the power plant of high strength,high corrosion resistance,high radiation environment of the steel.The true stress-strain curves of static recrystallization at different temperatures?950?,1000?,1150??,strain rate(0.1s^-1,0.5s^-1),deformation degree?40%,60%,70%?and interval?5s,30s?were studied by gleeble-1500d thermal simulator.The results show that the effect of deformation temperature and deformation degree on recrystallization of HD alloy steel is significant.The deformation temperature was 1150?,the strain rate was 0.1s^-1,and the deformation degree was20%.When the deformation degree was 50%,the strain rate was 0.1s^-1,the deformation temperature was 1000?,and the interval time was 30s,the alloy underwent complete recrystallization.The grain size analysis of the sample after two-pass compression shows that the grain size after recrystallization is about 20%finer than that without recrystallization.It is known from the test that the higher the deformation temperature is,the smaller the grain size after compression.Other technological conditions have little influence on the grain size after compression.The true stress-strain curves of dynamic recrystallization at different temperatures and strain rates were obtained by single-pass thermal simulation test,and the activation energy of dynamic recrystallization of HD alloy steel was calculated as Q=Rnb=437.84?KJ/mol?.The dynamic recrystallization model of HD alloy steel in the austenite high temperature region was determined by using the simulation method.The grain size analysis of the samples after dynamic recrystallization showed that the deformation degree increased from 60%to 70%,and the recrystallization grain refinement was about 50%.The strain rate had no significant effect on the dynamic recrystallization of HD alloy steel.Thermal expansion method is used to study the continuous cooling influence on HD steel group,by changing the cooling rate?0.01?/s,0.02?/s,0.05?/s,0.5?/s,1?/s,3?/s,5?/s,10?/s,30?/s,50?/s?get different cooling rate after the microstructure,and through the hardness with judgment,test results show that the cooling rate of1?/s began to appear obvious bainite,vickers hardness of about 381.88 at this time,when the cooling rate is 3?/s started to martensite structure,average vickers hardness of about 391.72,When the cooling rate reaches 50?/s,the microstructure is basically strip martensite.This article through to the HD alloy steel static,dynamic recrystallization,and the analysis of the organizational change process,understand the HD alloy steel under different heat treatment methods of organization evolution law and the situation of the static and dynamic recrystallization,improve the influence factors of different level,in order to determine more conform to the requirements of the plant production process,provide certain theoretical basis of the old process improvement.