Evaluation of hardness and impact toughness of drawn arc stud weldments on different structural steel grades

The drawn arc stud welding (DASW) procedure is usually qualified by visual examinations and practical destructive tests of the joint according to international standards. An assessment of the material properties in specific weld zone regions is not requested under consideration of their limited areas or the general joint dimension although the press welding process implies a complex metallurgy. Nonetheless, there is a need of knowledge regarding the heterogeneous material properties in the weld zone, especially when welding on base materials with specified strength and toughness behavior that might be significantly diminished. In this study, the local strength and toughness properties in welded joints of non-alloyed steel studs (Ø20 mm) on plates of different generic structural steel grades are investigated by hardness test and Charpy impact testing. A non-alloyed normalized structural steel (nominal yield strength 355 MPa) and a thermomechanically rolled fine grain structural steel of same strength as well as a quenched and tempered structural steel with high nominal yield strength of 690 MPa were examined. In the weld metal region, relatively similar hardness and low impact energy were determined despite of the different base plate steel grades. The base plate heat-affected zones suffer a strong embrittlement due to the DASW thermocycle.