Application of Coercivity Force in Pre-evaluation of Heat Treatment Quality

Conventional methods of heat treatment quality evaluation need destructive processing of materials, which were inefficient and unsuitable for products batch inspection. Then, a magnetic nondestructive evaluation method based on coercivity(H_c) was proposed, and the relationship between the microstructure, mechanical properties and coercivity force of carbon steel under different heat treatment conditions were studied. The results show that three typical microstructures of carbon steel corresponded to different coercivity force levels, the order of which was H_{c (martensite)} > H_{c (pearlite)} > H_{c (ferrite)}. The common mechanical properties were approximately linear with coercivity force. Though measuring coercivity force could not only identify the microstructure of carbon steel quickly, but also predict the mechanical properties quantitatively, this could be used to pre-evaluate the carbon steel of heat treatment quality.