Influence of surface aluminum content on microstructure and property of Q235 steel undergoing aluminizing

A powder aluminizing technique was used to fabricate the aluminizing layers on the surface of Q235 steel. The microstructures and properties of the aluminizing Q235 steel were studied. The results show that the continuous aluminizing layer can not be formed on the aluminizing surface with 2.6% aluminum content, but continuous aluminizing layer exists when aluminum content is 4.4% or more. The aluminizing surface with aluminum content of 4.4% or less is only consisted of α phase, and the surface with 36.2% is composed of α and AlFe phase. Hardness and high temperature oxidation resistance increase with increase in aluminum content on the aluminizing surface . The high temperature oxidation resistance of the specimen with 2.6% aluminum content on aluminizing surface is superior to that of pure Q235 steel, while the one with 51.2% aluminum is the same as that of1Crl8Ni9Ti stainless steel.