Effect Of Rolling Process On Microstructure And Mechanical Properties Of Q235B/304L Stainless Steel Clad Plates

Stainless steel clad plates have become increasingly popular in many fields because its excellent mechanical properties and anticorrosion property. Microstructure and mechanical properties of stainless steel clad plates which were welded by vacuum electron beam welding machine under different assembling and cooling method and rolling process were studied. The base of clad plates is Q235 B and the clad layer is304 L. The results show that:The asymmetrical assembling stainless steel clad plates were bended due to deformation resistance of base and clad layer were different. Microstructure of carbon steel consists of ferrite and pearlite, and the the volume fraction of pearlite in the steel increases with increasing reduction rate. The width of decarburized layer which exists in carbon steel decreases with increasing reduction rate. Chromium and ferric were found in the black zonal region by EDS. The carbon content increases rapidly when EPMA scanned the black zone. Chromium and nickel diffused because chemical potential exists between carbon steel and stainless steel. Chromium diffused further than nickel. So the black zonal region is chromium carbide which was made of carbon and chromium reaction. The black zone was a part of diffusion layer because the width of black zone was smaller than the width of diffusion layer. The thickness of diffusion layer decreases with increasing reduction rate and decreasing rolling passes.The black inclusions which exists at original bonding interface were Si-Mn oxide.Shear strength increased with increasing reduction rate and decreasing rolling passes.The plate profile of symmetrical assembling clad plate was good. The width of decarburized layer decreases with increasing reduction rate and increasing percentage pass reduction. The thickness of diffusion layer decreases with increasing reduction rate and decreasing rolling passes. The distribution density of black inclusions decreased with increasing total reduction rate and decreasing rolling passes.Micro-hardness changes with the thickness of decarbonization layer and diffusion layer. Shear strength increases with increasing total reduction and increasing percentage pass reduction.Microstructure of clad plates which were after water treatment was pearlite and ferrite and bainite. Decarburization layer and black zone almost disappeared. Shear strength far beyond the national standard of 210 MPa. The tensile strength is better than that of air cooling, but the elongation is lower than that of air cooling.