The Effect Of Electric Current Pulses On Microstructure And Mechanical Properties Of 14Cr2MoV Steel

As a non-equilibrium processing, electric current pulses shows its increasing applications in materials processing. Although the effects of electric current pulses (ECP) on the microstructures of materials have been extensively investigated, these works mainly focused on the mechanism evolution, but few on ECP applications. In this dissertation, the mechanical properties and microstructure evolution of a low carbon 14Cr2MoV steel under ECP treatment was discussed including:(1) The effect of ECP on martensitic transformation of 14Cr2MoV steel. (2) Improvement of mechanical properties of 14Cr2MoV steel under ECP.Compared with the conventional water quenching, the more refined and homogeneous martensitic microstructures were achieved after ECP. In addition, martensitic microstructures obtained from ECP possessed many more dislocations and much higher microhardness than that after water quenching. In view that the nucleation rate of a phase with higher electric conductivity was greatly enhanced during solid-state phase transformation caused by ECP, it was proposed that the nucleation rate of the austenite would be enhanced. Moreover, in combination with a very short treating time, the austenite grains have not enough time to grow, and then refined grains can be obtained finally.Furthermore, it is found that inhomogeneous mechanical properties of 14Cr2MoV steel caused by microstructure heritance can be eliminated after ECP. Though the microstructures almost had no changes, the shape of precipitation and the configuration of dislocations are changed under TEM observation. All of the above may result in the improvement of the mechanical properties after ECP.