The type-1aluminized(Al-10mass% Si)coating on hot stamped steel is used in commercial applications.The effect of temperature on microstructure and formability of the Al-10mass% Si coating was investigated.Hot-dip aluminized 22MnB5 steel was heated at 870,900,930,and 1 050 ℃ for 5 min.After heat treatment at different temperatures,the microstructure of Al-10mass% Si was characterized by field-emission scanning electron microscopy and energy-dispersive spectroscopy.The results show that when the Al-10mass% Si coating was heated at 870℃for 5min,three types of intermetallic phases were formed:two ternary Fe-Si-Al phases(Fe2SiAl7+Fe2Si2Al5and Fe2SiAl2+Fe2Si2Al5)and one binary Fe-Al phase(FeAl3).The phases in the coating became Fe2SiAl2+Fe2Si2Al5and FeAl3,the binary Fe-Al phase near the interface became Fe2Al5 and the Si-rich layers were decreased with the increase of heating temperature.When the heat treatment was 1 050℃for 5min,the Si-rich layer disappeared,the coating consisted of FeAl and Fe3 Al,and the Kirkendall voids were formed.When the heating temperature was increased through 870,900,and 930℃,the coating hardness was reduced and cracks were formed in the coating after hot stamping.The formability of the coating with temperature change was confirmed by a hot stamping test.When heated at 1 050 ℃,the coating was formable but continuous Kirkendall voids were observed. The type-1aluminized (Al-10mass% Si) coating on hot stamped steel is used in commercial applications. The effect of temperature on microstructure and formability of the Al-10mass% Si coating was investigated. Hot-dip aluminized 22MnB5 steel was heated at 870,900,930, and 1 050 ° C for 5 min. After heat treatment at different temperatures, the microstructure of Al-10mass% Si was characterized by field-emission scanning electron microscopy and energy-dispersive spectroscopy. The results show that when the the-Al- 10mass% Si coating was heated at 870 ℃ for 5min, three types of intermetallic phases were formed: two ternary Fe-Si-Al phases (Fe2SiAl7 + Fe2Si2Al5and Fe2SiAl2 + Fe2Si2Al5) and one binary Fe-Al phase became Fe2SiAl2 + Fe2Si2Al5and FeAl3, the binary Fe-Al phase near the interface became Fe2Al5 and the Si-rich layers were decreased with the increase of heating temperature. When the heat treatment was 1 050 ° C for 5min, the Si-rich layer disappeared, the coating consisted of f eAl and Fe3Al, and the Kirkendall voids were formed. At the heating temperature was increased through 870,900, and 930 ° C, the coating hardness was reduced and cracks were formed in the coating after hot stamping. The formability of the coating with temperature change was confirmed by a hot stamping test. heated at 1 050 ° C, the coating was formable but continuous Kirkendall voids were observed.