Alstar has far greater heat resistance than galvanized and cold-rolled steel sheet and thus keeps its original fine surface luster even when used for long periods at temperatures below 450 C.
If it is exposed to temperatures above 450c , however, the iron and aluminum become alloyed through mutual diffusion and the surface gradually turns from gray to a darker color
Since this alloy layer has a high fusing point, it will not melt even if exposed to a temperature above the fusing point of aluminum.
In addition, an oxide layer is produced on the coated surface by high temperature, which suppresses scale formation so that the sheet will not quickly become oxidized and worn until the diffusion progresses to the point where the aluminum coating becomes unable to control scale formation (approximately 600c) .The heat-resistant characteristics of AIstar are shown below.