Effects of Water Cooling Process on the Microstructure and Properties of Stainless Steel Clad Plates for Weathering Bridges

Stainless steel clad plates for weathering bridges were developed using thermo-mechanical control processing（TMCP） along with relaxation and tempering processes. The effects of three different water cooling processes on the microstructure and properties of clad plates were studied. The results showed that the microstructure of the carbon steel substrate consisted of granular bainite， quasi-polygonal ferrite， and pearlite under all tested water cooling conditions. As the water entry temperature decreased， the decarburized layer at the carbon steel substrate at the clad interface became wider， and the volume fraction of proeutectoid ferrite in the substrate increased， resulting in a decrease in strength， especially a reduction in yield strength from 572 MPa to 527 MPa， and then a reduction in yield ratio from 0.87 to 0.83. At a constant water entry temperature， a lower self-tempering temperature promoted a more complete bainitic transformation. This increased the tensile strength from 658 MPa to 710 MPa， while the yield strength remained largely unchanged， thereby reducing the yield ratio and meeting the performance requirements for the 316L+Q500qENH composite system.