Investigation on gas metal arc weldability of a high strength tool steel

In this paper, gas metal arc weldability results of a particular advanced tool steel are presented. Indeed, the study was focused on the weld profile, microhardness and microstructure of the joints. The aim was to identify an appropriate filler material and optimize the process parameter. The validation of results started with a careful metallographic analysis of the joints, in order to verify that the metallurgical properties of the material were not compromised by the welding process. In the following step, all the non-destructive and mechanical tests, imposed by procedure qualification, were performed in order to have a complete characterization of the joints. For all the wires used, hardness tests highlighted that the use of low heat input and a high number of beads causes an increase in the Heat Affected Zone (HAZ) hardness up to values equal to or exceeding the limits imposed by the European standard on the process qualification. To avoid this problem, it was therefore necessary to adopt high electric parameters and thus high heat inputs. The filler material that gave the best results, in terms of uniformity of mechanical properties, is the rutile flux wire.