Multi-factorial analysis of Nd:YAG laser welding of high carbon steels: Effect of laser parameters and weld geometry

Abstract

The combination of laser processing, different welding geometries and techniques introduces a large number of factors which potentially influence the weld quality. A multi-factorially experiment was designed to assess the effect and interactions of a number of different laser parameters and different beam delivery systems. This included: pulse width, pulse repetition frequency (PRF), translation speed, and normal, pre-heating and post-heating of the weld. A general linear model was used to find the laser parameters which had a significant effect on the weld quality. This resulted in a faster, more efficient optimisation process. The weld quality was quantified by measuring the aspect ratio, weld volume formation rate and tensile strength. The welding was done with Lumonic’s MS830 Nd:YAG laser, operating at 1.06 μm, and with a maximum output power capacity of 400 watts. A dual-beam fibre optic delivery system was used to achieve pre-heat and post-heat treatments with a total power of 285 Watts. For the pre-heated geometry, a significant triple-interaction effect was observed for the measurement of weld volume formation rate. Interestingly, for all of the range of laser parameters investigated for the measurements of the tensile strength, there was no significant effect for the double or triple parameter interactions with the normal and post-heated weld geometries. For the pre-heated geometry, however, the interaction between the welding velocity and pulse width was significant. This investigation indicates the significant laser parameters, their interactions, and weld geometries that effect the weld’s: aspect ratio, tensile strength and weld volume formation rate.The combination of laser processing, different welding geometries and techniques introduces a large number of factors which potentially influence the weld quality. A multi-factorially experiment was designed to assess the effect and interactions of a number of different laser parameters and different beam delivery systems. This included: pulse width, pulse repetition frequency (PRF), translation speed, and normal, pre-heating and post-heating of the weld. A general linear model was used to find the laser parameters which had a significant effect on the weld quality. This resulted in a faster, more efficient optimisation process. The weld quality was quantified by measuring the aspect ratio, weld volume formation rate and tensile strength. The welding was done with Lumonic’s MS830 Nd:YAG laser, operating at 1.06 μm, and with a maximum output power capacity of 400 watts. A dual-beam fibre optic delivery system was used to achieve pre-heat and post-heat treatments with a total power of 285 Watts. For the pre...