Study On Dual Phase Deformation And Rolling Simulation Of CU-P-CR-NI-MO Weathering Steel

Hot deformation behavior of duall-phase range, single-pass rolling simulation and multi-pass rolling simulation of weathering steel Cu-P-Cr-Ni-Mo were investigated by using Gleeble3500simulator. And the corresponding microstructure was also studied. All this work laid the theoretical foundation for refinement of ferrite grain throuth thermo mechanical control process (TMCP).Hot deformation behavior of duall-phase range of Cu-P-Cr-Ni-Mo weathering steel was investigated by using Gleeble3500simulator in the temperature range from700℃to950℃and strain rates of0.01-10s-1. The results shown that at the range of700-800℃the peak stress decreases with the temperature increasing and reaches a minimum at800℃; At the range of800-850℃, the peak stress increases with the temperature rising; Then the peak stress showed a decreasing trend when the temperature exceeds850℃Based on the experimental results of hot deformation and CCT diagram of deformed austenite, single pass rolling simulation processes of Cu-P-Cr-Ni-Mo were deduced. Then the dual-phase microstructure was produced by single-pass rolling simulating on Gleeble-3500thermal simulator. The technology is:the deformation temperature of825-950℃, reduction of30,50and70%, cooling rate of1and3℃/s. The results shown that the grain size of ferrite decreases with deformed temperature decreasing, rolling reduction increasing and cooling rate increasing. Dual-phase microstructure with fine ferrite grain of7.0μm can be obtained with deformed temperature of825℃, reduction of70%and cooling rate of3℃/s. The martensite volume fracture increases with deformed temperature increasing, rolling reduction decreasing and cooling rate increasing. The martensite volume fracture of23.4%can be obtained with deformed temperature of950℃, reduction of30%and cooling rate of3℃/s.Continuous hot-rolling with three passes and five passes of weathering steel Cu-P-Cr-Ni-Mo has been simulated by using Gleeble-3500simulator. The microstructure of the hot-rolled steel under different conditions is characterized as irregular distribution of island-shaped martensite in the matrix of equiaxed ferrite grains. The grain size decreases with decreasing temperature, increasing reduction and diminishing pass reduction. Minimum ferrite grain with size of1.41μm can be obtained with deformed temperature of900-850-800℃, reduction allocation of60-40-30%.