Innovation of conventional heat treatment and microstructural modification of steels by electromagnetic processing

摘要

The microstructural modification and property improvement of steels through the introduction of a magnetic field, especially a high magnetic field, to their solid phase transformation has aroused much attention in recent years. The effect of the magnetic field on martensitic transformation, bainitic transformation and ferritic transformation of steels has been the main topic of this domain. It has been found that the magnetic field can increase the martensitic and bainitic transformation start temperatures and accelerate the transformation. The application of a high magnetic field to the proeutectoid transformation in steels started relatively late, as there existed technical difficulty in obtaining high temperature and high magnetic field at the same time. Now more attention has been shifted to the diffusional transformations of steels under high magnetic fields. The author's group has been active in this topic and conducted both theoretical and experimental researches in this domain. The main achievements in revealing the thermodynamic and kinetic effects of high magnetic fields on austenite decomposition and thus its positive application to practical heat treatment procedures are overviewed. In addition, the microstructural modification behaviors during martensitic decomposition by the magnetic field and the possible property improvement to a high strength low-alloyed steel are also summarized.