Effects of PWHT on Weld Metal Properties of YS 460 MPa Steels for Ship and Offshore Structures

This paper has an aim to study the effect of PWHT(for 140min.at 600 ℃) on FCAW weld metal properties (tensile, charpy impact and CTOD value) of YS 460 MPa steels for ship and offshore structures.On the basis of these study, it was found that strength was decreased and elongation was increased by PWHT.These phenomenon resulted from the reduction of acicula ferrite volume fraction by grain growth.Also, Charpy impact and CTOD value were decreased by PWHT.These phenomenon resulted from grain growth.Because the grain boundary grown by PWHT can play a role as crack initiation site and make the crack propagate more easily.Although weld metal properties were decreased by PWHT, tensile and impact properties could meet the class societies requirements for welds of YS 460 MPa steel, but decrease of fracture toughness need to be consider seriously.