Electron backscatter diffraction study on bonding and crack formation mechanism of laser cladding NiTi alloy on 316 substrate

NiTi alloy was prepared on 316 substrate by laser cladding with the aiming of clarifying the mechanism of crack formation and interface bonding. The intermediate layer generated in situ at the bonding surface possesses a low stress level. The high hardness brittleness caused by Fe element distributed along the molten pool boundary is the starting point of coating cracking, and the crack is transgranular fracture. The pole diagram shows that from the interface to the top of the coating, the preferred grain orientation varies from {1 0 0} to {110}, which benefit from the conversion of the maximum temperature gradient.

Automated summary

NiTi alloy was prepared on 316 substrate by laser cladding. The study aims to clarify the mechanism of crack formation and interface bonding. A low-stress intermediate layer is generated at the bonding surface. The high hardness brittleness caused by Fe element leads to coating cracking, which exhibits transgranular fracture. The preferred grain orientation varies across the coating, benefiting from the conversion of the maximum temperature gradient.