Aging Effects on Magnetic Properties in a 12Cr-W Steel

Changes of magnetic and mechanical properties by high-temperature, isothermal agings were studied in a 12Cr-W steel. Results of coercivity, hysteresis loss, and Vickers hardness obtained from the aged specimen decreased with second order exponential functions of the aging time increased. These phenomena were analyzed using the scanning electron microscope, backscattered electron, and X-ray diffraction; from a microstructural viewpoint, the aging resulted in a coarsening of the tempered carbide (Cr 23 C 6 ) and a formation of the Laves (Fe 2 W) phase. These microstructural changes are closely related with a reduction of the mechanical strength with the aging time.