Investigations on the microstructure of drawn arc stud welds on structural steels by quantitative metallography

Abstract

The drawn arc stud welding is widely applied in steel construction, and its welding procedure can be qualified according to different standards by visual examinations and practical destructive tests of the resulting joint. An evaluation of the material properties is usually not requested particularly considering the locally limited weld region. Nevertheless, there is a need of knowledge regarding the complex press welding process metallurgy and resulting heterogeneous material properties in the welded zone, especially when welding on base materials with specified strength and toughness behavior that might be significantly diminished. In this study, the metallurgy of standardized large low alloyed Ø20 mm steel studs welded on plates of different generic structural steel grades is comprehensively analyzed by quantitative metallography. Structural steels with a moderate nominal yield strength of 355 MPa in non-alloyed normalized and micro-alloyed thermomechanically rolled delivery condition as well as a quenched and tempered structural steel with a high nominal yield strength of 690 MPa were investigated comparatively. Despite the different base plate compositions, very similar microstructures were found in the weld metal, whereas a typical quenching microstructure that strongly depends on the steel grade occurs in the heat-affected zone. A basic suitability of all steel grades regarding the DASW metallurgy was found.