Effects of Hot Bending Parameters on Microstructure and Mechanical Properties of Weld Metal for X80 Hot Bends

Mechanical properties of weld metal are the key factors affecting the quality of heavy-wall X80 hot induction bends. The effects of bending parameters on the mechanical properties of weld metal for hot bends were investigated by simulation conducted on a Gleeble-3500 thermal simulator. Continuous cooling transformation (CCT) diagrams of the weld metal were also constructed. The influences of hot bending parameters (such as reheating temperature, cooling rate, and tempering temperature) on the microstructure and mechanical properties of weld metal were also analyzed. Results show that the strength of all weld metal specimens is higher than the value indicated in the technical specification and increases with the increase of reheating temperature, cooling rate, and tempering temperature. The impact toughness is apparently related to the variation of reheating temperature, cooling rate, and tempering temperature.