Frictional behavior of ZnO coated aluminized steels under hot drawing tests with coated tools

It is desired that the coefficient of friction is reduced in hot stamping of the aluminized 22MnB5 steels. It was reported that ZnO coated aluminized steel reduced the coefficient of friction and the amount of Al-Fe intermetallic compounds (IMC) adhered on the tool surface. In this paper, the frictional behavior of ZnO coated aluminized 22MnB5 steel when sliding against tool steel was investigated. The non-coated tool and the coated tools with TiN, TiAlN and DLC-Si were used. The experimental tests were carried out under dry condition using the hot flat drawing test machine. The coefficients of friction for the drawing distance were measured. After drawing, the Al-Fe IMC adhered on the tool surface was analyzed and the profile of tool surface was measured. For the non-coated tool, the amounts of adhered Al-Fe IMC of ZnO coated aluminized 22MnB5 steel were lower than that of aluminized 22MnB5 steel, and the coefficients of friction decreased, On the other hand, for the coated tools, the coefficient of friction became lower and the adhered aluminum became significantly thinner.