STUDY OF FILLER METAL MIXING AND ITS IMPLICATION ON WELD HOMOGENEITY OF LASER-HYBRID AND LASER COLD-WIRE WELDED THICK AUSTENITIC STAINLESS STEEL JOINTS

摘要

An austenitic stainless steel AISI 316L grade basematerial with butt joint thickness of 15 mm anddifferent root gap preparation was single pass weldedusing both laser-GMA hybrid and laser cold-wirefeeding process. The aim was to be able to study thefiller metal mixing in thick section laser welding andthe effect of processing parameters on it. Particularinterest was to examine how homogenous filler metalmixing is across the whole weld cross-section from theweld surface to the root portion. Avesta 2205 duplexstainless steel filler wire was used in order to producean over-matched weld metal composition differingfrom the base metal. Chromium was used as a traceelementas its distribution and quantity within the weldcross-section was identified using SEM and EDSanalysis. Moreover, micro- and macroscopicmetallography was carried out to examine emergedweld microstructures and their features. In thetechnical paper the effect of influencing parameters onthe amount and homogeneity of filler metal mixingsuch as root gap preparation, wire feeding orientation(leading vs. trailing) and welding process (hybrid vs.cold wire) are compared and discussed.