Effects of external loads on microstructure and properties of P92 steel

During the metal-solid phase transition, the mechanical properties of metal materials are affected by the nucleation rate and growth rate of grain. In this work, external loads (200 N, 400 N, 600 N, and 800 N) were applied to P92 steel during the heat treatment process in an attempt to improve and optimize the microstructure and mechanical properties of P92 steel. The effects of different external loads on the morphology, corrosion resistance, microhardness, and mechanical properties of P92 steel were investigated by using optical microscopy, microhardness testing, electrochemical testing, tensile strength measurements, and semi-automatic impact tester. The results show that the grain growth rate of P92 steel was moderate under an external load of 600 N; the grain distribution was uniform and orderly whereas the microhardness and corrosion resistance of the sample reached the optimum value (528 Hv). The tensile strength, yield strength, and elongation of the sample were 786 MPa, 525 MPa, and 37.8 %, respectively. However, the impact power of the P92 steel under an external load of 200 N was the minimum, and its average value was 132 J. The results depict that the external load can improve the mechanical properties of P92 steel.