热处理对S355钢显微组织和耐腐蚀性能的影响OA

To explore the influence of heat treatment processes on the microstructure and corrosion resistance of low-carbon microalloyed steel,and to fill the gap in systematic research on the corrosion resistance behavior of low-carbon microalloyed steel,S355 steel was selected as the research object.Through controlled variation heating temperatures(950～1 100℃)and cooling methods(water cooling,oil cooling,air cooling,furnace cooling),the steel was subjected to heat treatment.The microstructure was observed using scanning electron microscopy and metallographic microscope.The grain size was measured by Image Pro Plus software,and the hardness was tested with a Vickers hardness tester.The corrosion resistance was evaluated via polarization curves and Nyquist diagrams obtained using the CHI660E electrochemical workstation.The results showed that,at a heating temperature of 1 050℃,the water-quenched sample exhibited a fully lamellar martensite(LM)microstructure,achieving a peak hardness of 412.17 HV0.2.The hardness of the 1 100℃water-quenched sample decreased due to grain coarsening;at the same heating temperature,the slower the cooling speed,the lower the hardness.The hardness of the water-quenched sample was significantly higher than that of samples cooled by other methods.In terms of corrosion resistance,the water-quenched sample at 1 050℃had the largest self-corrosion current density and the lowest polarization resistance Rp of 734.3 Ω,indicating the poorest corrosion resistance;the air-cooled sample had the best corrosion resistance due to the finer ferrite+pearlite(F+P)microstructure.Reasonable selection of heat treatment parameters can optimize the comprehensive performance of the material,providing a theoretical basis for the application of S355 steel in marine environments.