Fatigue crack growth resistance of electron beam welded joints from high strength steels

Abstract

The research focused on the fatigue crack growth resistance of electron beam welded joints of quenched and tempered S960QL and termomechanically rolled S960M high strength structural steels. In the welding experiments, 15 mm thick base materials were used to prepare the autogenous welded joints with I weld geometry. The three-point bending (TPB) specimens used for the fatgure crack growth tests were designed to be perpendicular or parallel to the characteristic directions, and the notch positions were also changed for the analysis of the characteristic parts of the welded joints (weld, fusion line, heat-affected zone). The cracks propagating during our tests correspond to the different crack appearances in the real welded structures. The fatigue crack growth resistance of the electron beam welded joint of the examined S960M steel proved to be significantly different in the examined directions, the S960QL steel did not show such a difference. The electron beam welded joints of S960QL steel proved to be significantly more sensitive to the location of fatigue cracking cracks in both directions than the joints of the examined S960M steel.