Analysis of metallurgical and mechanical properties of laser welded super austenitic stainless steel

Abstract

PurposeLaser welding under high power, high degree of automation and high production rate is extremely advantageous in automotive application. Super austenitic stainless steel is the preferable material for high corrosion resistance requirements. These steels are relatively cheaper than austenitic stainless steel and it is expensive than nickel base super alloys for such applications. The main purpose of this paper is to present the investigations of the microstructure and mechanical properties of super austenitic stainless steel butt joints made by 3.5 kW cooled slab CO2 laser welding using different shielding gases such as argon, nitrogen and helium.Design/methodology/approachThe tensile and impact tests were performed and the fractured surfaces were analyzed by scanning electron microscope. The hardness across the joint zone was measured. The X‐ray diffraction technique was used to analyze the phase composition. The microstructure of the laser welds were analyzed through optical microscopy.FindingsThe tensile sample fractures indicate that the specimen fails in a ductile manner under the action of tensile loading. The impact fracture surfaces of the different shielding gas laser welded joints show mixed mode fractures, that is, ductile and cleavage fractures. The hardness values of the Helium shielded laser joints in the weld metal regions are much higher than the others.Research limitations/implicationsThere is no limitation, except for the availability of the high beam power laser welding machine.Practical implicationsThe only practical implication is the laser welding shop hazard during the experiment.Social implicationsSocial implication is limited. The only hazard during the laser welding is that it may affect human body tissues.Originality/valueThe research work described in the paper is original.