Microstructures and Mechanical Properties of HAZ of Weld Thermal Simulation for 10Ni8CrMoV Steel

Microstructures and mechanical properties of HAZ of 10Ni8CrMoV of 980 MPa high strength steel were studied. The different regions of HAZ were simulated by weld thermal simulation technique. Microstructure observation,phase analysis,and corresponding tensile and impact tests for different regions in HAZ were made. The results indicated that the yield strength and plasticity were significantly reduced in the coarse grain zone; impact toughness of different regions in HAZ had no obvious change with the changing of the heat inputs; critical zone of HAZ had the worst impact toughness and was the weakest part of the HAZ; the main reason for higher impact toughness of coarse grain zone was that more austenite films was continuously distributed in this area.