Hot cracking in high power laser beam welding of thick high strength structural steels under restraint conditions Available to Purchase

High power laser beam welding represents a cost-effective alternative for fast joining of thick components. However, the reliability of the welded structures can be severely affected by solidification crack formation, caused by constructional restraints. Experimental investigations using 15 mm thick plates of the fine grained structural steel S690, welded with a 20 kW fiber laser under different restraint conditions revealed a relationship between hot cracking susceptibility and restraint intensity. Systematic laser welding experiments were conducted in the IRC (Instrumented Restraint Cracking)-test facility, under both free shrinkage as well as defined restraint intensities. In order to assess the stress-strain condition of the weld during solidification which is crucial in the hot crack formation process but also difficult, if not impossible to acquire experimentally, a two-dimensional thermo-mechanical finite element model of the IRC-Test was developed. The results constitute a good approach to explain and understand the detrimental effects of high restraints on hot cracking phenomena during laser beam welding.