Theory and experimental research on controlling crack in double-scanning laser cladding process

A new craft of laser cladding,unidirectional powder feeding and double scanning,was developed to solve the problem of cracking in the cladding coats.The temperature field and stress field of laser cladding were computed.The results indicate that the value of stress is very large and the stress concentration problem is serious at the top of cladding coat and the joint between coat and base material in the process of unidirectional scanning.After the second scanning,the value of stress can be decreased and the stress concentrated at the top of cladding coat can be eliminated.The results of laser cladding 45 steel with Ni60 alloy powder by the craft of unidirectional powder feeding and double scanning show that the cracking of the coats can be avoided both in single-pass cladding and multi-pass lap cladding by the craft,which is effective and feasible for controlling crack in laser cladding.