Structural behavior of single‐sided welded HSS‐T‐joints with softening in the heat‐affected zone

In the case of high‐strength steels, softening in the heat‐affected zone (HAZ) is possible due to the heat input during the welding process. Therefore, in addition to weld failure, other forms of failure of the welded joint cannot be excluded. Within the framework of the AiF‐FOSTA research project P1453, experimental investigations are carried out on single‐sided welded T‐joints. The aim of the investigations is to analyze the failure modes resulting from softening in the HAZ. Specimens with different weld types, steel grades, plate thicknesses and cooling times t_8/5 are investigated. The softening of the HAZ is experimentally evaluated for thermome‐chanical rolled and quenched and tempered high‐strength steels with yield strengths from 500 to 960 MPa by thermo‐physical forming simulations. The results will be used to improve the design rules for welded joints. In particular, this includes a consideration of the heat‐affected zone in the design of welded joints made of high‐strength steels. The paper presents the results of thermo‐physical forming simulations. By measuring macrosections of butt joints, a description of the expansion of the heat‐affected zone as a function of peak temperature and cooling time is presented. Furthermore, results of structural mechanics studies for the load bearing capacity analysis of single‐sided welded T‐joints are presented. This is followed by a detailed description of the experimental test program.