Evaluating method for Charpy notch toughness of carbon steel welded joint by Laser beam welding

Abstract

This paper deals with the useful estimating method for toughness of welded metal by Laser Beam Welding (LBW). Under present circumstances, LBW is not applied for non-redundant structural member, because of toughness of the welded joint cannot be verified due to Fracture Path Deviation (FPD). In the study, 7 types of carbon steels and their welded joints have been evaluated by Charpy impact test and CTOD test. Many FPD has been observed and it is confirmed that FPD probability is tend to decrease, as the test temperature decreases. Therefore, the estimating method for toughness of LBW welded metal; using data tested in lower temperature has been established. For estimating a proper transition temperature, 3 valid data (at least one of them measured above the temperature as "Energy transient temperature -20 degrees") is required. Using the method, Charpy absorbed energy has been estimated with sufficient precision.