Suppression of edge cracking and improvement of ductility in high borated stainless steel composite plate fabricated by hot-roll-bonding

In the nuclear fuel reprocessing systems, the demands for high borated stainless steels are increasing due to their excellent thermal neutron shielding properties. However, the eutectic borides precipitating around the matrix grains could easily result in the severe edge cracking for the ingot-casting steels during processing. In this paper, a 3-layered composite plate consisting of 2.1 wt% B stainless steel and boron-free austenite steel was fabricated by welding and hot-roll-bonding. Besides, the microstructure evolution and the tensile properties of the composite and non-composite plates were comparatively investigated. It was found that the edge cracking of the composite plate was significantly suppressed comparing with the non-composite plate prepared by conventional hot rolling. Moreover, the ductility of the composite plate at room-temperature was greatly enhanced. The tensile elongation reached to 15.5% for the specimen after 1100 °C × 30 min solution treatment, and that was approximate 2.5 times as high as the elongation of the non-composite specimen. In addition, the inhibition mechanism of edge cracking during hot-roll-bonding, and the enhancement mechanism of tensile plasticity for the composite plates were both explained. The present work not only develops a new high borated stainless steel with the excellent mechanical properties, but also provides a promising method to suppress the edge cracking for some other metallic materials with poor hot workability.