Investigations on the Fracture Toughness of Electron Beam Welded Steels

Abstract

Beam welded joints made from fine grain steels show martensitic micro structure, high weld hardness and thus low toughness in the weld seams. At the same time there is a risk for these welds to have crack-like defects that cannot be detected during the production and which grow due to cyclic loading. If such structures are used in areas with low ambient temperatures, it may come to brittle failure of the component. To secure components against such failure, fracture mechanic tests were carried out on electron beam welded SE(B)-samples made from S690QL and S960QL and the J-integral was determined. In order to describe the scattering of the results in the temperature transition region the results were evaluated by means of the Master Curve concept in accordance with ASTM E 1921. Afterwards the reference temperature in the transition range, T0, was determined and correlated with the T27J- temperature of Charpy V-notch tests.