Relationship between Thickness,Temperature Field and Microstructure Evolution of Q390 Steel Plate under TMCP Process
Q390 hot-rolled steel plates with three different thicknesses were prepared by TMCP process,and the influence of thickness on the microstructural evolution and hardness was revealed based on the finite element analysis of the cooling temperature field.The results show that under the same cooling conditions,there are obvious differences in the thickness direction of the 40 mm thick hot-rolled steel sheet,that is,the edge is dominated by bainite,while the core is ferrite and pearlite,corresponding to a microhardness difference of about 40 HV.The microstructure in thickness direction of the 13 and 20 mm thick hot-rolled steel sheets is relatively uniform,mainly bainite,and the microhardness distribution is relatively uniform.The finite element analysis of the temperature field shows that the ferrite and pearlite in the core of the thick plate(40 mm)sample is mainly formed in the air cooling stage;while for other thick steel plates,in the water cooling stage,the core and the edge obtain relatively consistent final results.The cooling temperature and cooling rate are all in the bainite transformation temperature range.
Q390 low alloy high strength steelthemal-mechanical control process(TMCP)microstructuretemperature fieldhardness
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