Optimal laser welding process parameters and expected weld bead profile for P92 steel

Abstract

P92 steel is classified as one of the creep strength enhanced ferritic steels, whose welding plays a crucial role in power industries. The best choice for such materials is the laser welding in open atmosphere with an inert gas shield. Compared to the frequently being used Taguchi based grey relational analysis, a simple and systematic approach known as the modified Taguchi design of experiments is utilized for P92 steel to obtain the optimized laser welding process parameters and the expected range of output responses. The complicated non-linear relationship between the laser welding process parameters (viz., laser power, welding speed and focal position) and the welding bead geometry (such as depth of penetration, weld width and heat affected zone width) is developed through empirical relations, which are validated by comparing with existing test results. Most of the test results are found to be within the expected range. From the ANOVA analysis the process parameter, viz. the focal position is found to have negligible variation on the overall mean value of the output responses and hence, the process designer can opt for any one the set levels of the focal position during welding operations.