Abstract:In order to reduce the intermetallic compounds formed during the application of an Al-7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB) and hot stamping, 2-6 wt % Si was added to the coating to change the reaction layer. The coating was run at 690 • C for 120 s. Al 9 FeNi phases were formed on the steel interface, Fe 2 Al 5 was formed on the steel, FeAl 3 was generated between the existing layers, and flake-type Al 2 Fe 3 Si 3 was formed in the Fe 2 Al 5 phase, depending on the Si content. In addition, as Si was added to the coating, the thickness of the Fe 2 Al 5 phase decreased and the thickness of the Al 9 FeNi phase and Al 2 Fe 3 Si 3 increased. The decrease in the thickness of the Fe 2 Al 5 phase was mainly due to the effect of the Si solid solution and the Al 2 Fe 3 Si 3 formation in the Fe 2 Al 5 phase. The reason for the growth of Al 9 FeNi is that the higher the Si content in the coating, the more the erosion of the interface of the steel material due to the coating solution. Therefore, the outflow of Fe into the coating liquid increased.