Influence of Austenitizing Holding Time on Microstructure and Property of Aluminum Silicon Coating Hot Stamped Steel

AS150 aluminum silicon coating was prepared on 22MnB5 hot stamping steel substrate, and the influences of austenitizing holding time on microstructure and property of 22MnB5 aluminum silicon coating hot stamping steel were studied. The results indicate that with the increase of austenitizing holding time, the Fe-Al-Si phase of aluminum silicon coating changes from slender and continuous Fe₂SiAl₂ phase near the interface to discontinuous Fe₃SiAl₃ phase, and finally to coarse and discontinuous Fe₄SiAl₄ phase offset to the coating surface. The migration amount of Al, Si and O elements from the coating surface to the substrate along the depth direction generally increases, and the maximum migration depth of O element is about 1.15 μm, and the migration of Fe element from the substrate to the coating surface along the depth direction increases obviously. The surface average roughness R_a and peak count R_pc of aluminum silicon coating increase rapidly at first, and then decrease slowly. When the holding time is 6 min, R_a and R_pc reach maximum, corresponding to 2.01 μm and 186. The total thickness of the coating and the thickness of the interface bonding increase gradually, and the microhardness of substrate increases rapidly at first, and then tends to change slowly.