A pathway of post-weld heat treatment (PWHT) to eliminate heat affected zone (HAZ) softening and improve the strength of the welded joints of DP980 steel was developed. It is found that the high temperature isothermal transition at 750–950 °C followed by water-quenching significantly influences the strength and fracture location by changing the microstructures of the welded joint. The block martensite is distributed discretely in the island ferrite after PWHT, which causes ferrite to deform continuously in space. At the same time, the microstructure of joints is more uniform after PWHT. As a result, the highest strength (1146 MPa) can be obtained by PWHT at 950 °C, which is about 1.35 times that of the as-welded joint.
|Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
|Published - 31 Jan 2022