Investigation of the hardness-toughness-relationship of a welded joint after different heat-treatment cycles

Due to the increasing use of high-strength steels, the requirements for filler materials are also growing. To investigate the toughness properties of the corresponding welded joints, a new testing method has to be developed. This new test method uses subsized Charpy-V specimens (abbr. KLST samples) which permit the analysis of welded sheets with a thickness of approx. 5 mm. For the development and evaluation of the new method, a high-strength steel (S690) and a high-strength filler metal (T 69 5 ZMn2NiCrMo M M1 H5) were used. Physical simulations of various post-weld heat treatment cycles and multipass welding were conducted in a dilatometer. After the heat treatment, the toughness of the specimens was tested by Charpy impact testing and the hardness with Vickers hardness measurements. Additional metallographic investigations were also carried out. The results show that the method provides useful results for a wide range of parameters and it is appropriate for the simulation of post-weld heat treatment cycles and multipass welding on welded joints.