Abstract: Alternating current field enhanced pack chrom-aluminizing (ACFPCA) and the conventional pack chrom-aluminizing (CPCA) at 800 ℃ on the surface of the Q195 steel specimens were carried out, respectively, in which the inward diffusion of aluminium dominated, and then adding chromium powder to the aluminizing agent. The layer structure, phase, thickness and distribution of microhardness along the depth direction of the layer were studied by means of metallographic microscopic observation, X-ray diffraction analysis and micro-Vickers hardness test. The results show that compared with single aluminizing, adding a small amount of chromium powder has little effect on structure and thickness of the CPCA layer except increasing the hardness of the subsurface layer. Alternating current field (ACF) promotes both aluminizing and chrom-aluminizing. Compared with single ACF enhanced pack aluminizing (ACFPA), the inward diffusion of Al is further accelerated by adding a small amount of chromium powder to the aluminizing agent in ACFPCA. However, adding a small amount of chromium powder has little effect on increasing the hardness of the subsurface. With the increase of chromium powder in the pack agent, the ACFPCA layer's thickness increases first and then decreases. When 0.1% chromium powder is added, the promoting effect is the most significant and the obtained layer is about 123 μm thick, while the thickness of the ACFPA layer is about 50 μm and that of CPA layer is only about 18 μm.

Key words: pack chrom-aluminizing, alternating current field, Q195 steel