Diffusion Kinetics of Boronized ASP (R) 2012 Tool Steel Produced by Powder Metallurgy

摘要

Tool steels are generally preferred for shaping and blanking dies in sheet forming industry. A mild heat treatment is needed to bring about the properties needed for long lasting operational characteristics such as low wear rate, high hardness and durability. Blanking and deep drawing processes, plastic injection moulding and various machine components are typical applications of such steels, which can also be produced by powder metallurgy such as ASP (R) 2012 class tool steels with a high hardness value as much as 63 HRC. In this study, boronizing was carried out on ASP (R) 2012 tool steels and diffusion kinetics were investigated for different temperatures (1123, 1173, 1223 K) and holding times (2, 4 and 6 h) in Ekabor-2 powder. The microstructural development and phases in the specimens were investigated by using optical microscopy and Shimadzu XRD-6000 brand X-ray diffraction using CuK alpha (lambda = 1.5406 angstrom) radiation, respectively. The kinetics study showed that high alloying elements retards the diffusion in the bulk however borides of W2B, Mo2B and CrB were observed within the hard boride layer on ASP (R) 2012 tool steel surface.