Study On The Phase Transformation Mechanism Of Wide-strip Hot Rolling30CrMo Steel Produced By CSP Process

The demand for high-quality steel materials is growing today, and the use ofadvanced steel technology to produce steel material has become a trend. In this context,researchers have gradually studied how to produce a variety of steel products with CSPprocess. Compared with traditional process this new one has many different processingparameters need to be developed according to its characteristics, which further produceshigh-quality strip products. The change of phase of steel materials after thermalprocessing has a great influence on the final microstructure and properties. Thereforethe research for the impact of deformation and coiling process based on CSP process onthe phase transition is an important part.This paper takes30CrMo steel produced by some Steel Works under CSP processas the study object. The dynamic CCT curves are measured by thermal simulation test,and compared with the steel static CCT curves. The results showed that the dynamicCCT curve over Cold austenite to pearlite transformation temperature has increased, andat a lower cooling rate of bainite transformation occurs. Furthermore the physicalmetallurgy method is made use of to study how deformation (deformation temperature,deformation, deformation rate) and coiling process affect30CrMo steel isothermaltransformation. The results showed that with the decreasing deformation temperature,isothermal transformation became faster, which refined pearlite lamellar spacing andimproved the rigidity. When the deformation amount gradually increased from30%to50%,the phase change completion time reduced after the first increase. Afterdeformation amount reached a constant value, the phase change process was inhibited.But pearlite lamellar spacing was gradually reduced, and the hardness increased. Andthe deformation rate change from1s-1to20-1in the process. But also the first to playafter isothermal transformation promote the role of inhibition.Pearlite lamellar spacing decreases, the hardness value increases. In the coiling process, the influence of coilingtemperature of700℃~550℃on30CrMo steel isothermal transformation was studied,which concluded that between700℃~580℃, what it mainly happened was thetransformation from supercooled austenite to pearlite. It was always promotingisothermal transformation. And with the coiling temperature decreased, pearlite lamellarspacing decreased, the hardness increased. Thanks for bainite transformation at580℃,the isothermal transformation completion time exceeded1800s and there was asignificant increase in hardness. Through experimental research, we had a initiatoryknowledge about phase transformation and organizational performance about30CrMosteel after thermal processing, which can provide some theoretical referring basis forindustrial production, and it has achieved some success.