Effect of Heat Treatment on the Microstructure and Strength of Stainless Steel-Clad Plate

A 316L/Q345R stainless steel-clad plate after hot rolling was subjected to three heat treatments: rapid cooling, rapid cooling and tempering, high-temperature rapid cooling, and low-temperature slow cooling to improve its microstructure and properties. Its specimens were prepared by of an hot rolling evacuated package. Optical microscopy and energy dispersive spectroscopy were applied to examine the microstructure and constituents of the specimens. The mechanical properties under different treatments were evaluated in shear, tensile, and impact tests. The results demonstrate grain refinement and improved properties after heat treatment. After rapid cooling the microstructure of the specimen is mainly composed of martensite, strength increases, ductility is poor, and elongation is relatively low, only 12.7%. The microstructure and ductility are certainly at their optimum after rapid cooling and tempering, elongation tends to 16.7%, but performance still does not meet the practical requirements. After high-temperature rapid cooling plus low-temperature slow cooling, the microstructure mainly consists of bainite, fine ferrite, and a small amount of pearlite. The clad plate exhibits excellent performance due to the combined soft and hard phase structure, shear strength reaches 397 MPa, and elongation is 22.2%, both fulfill the requirements.