Hot-Dip-Aluminizing, is a versatile technique for protection of iron and steel from harsh environments. Morphology , profile as well as growth of the intermetallics formed on the interface of aluminium coating and the substrate are affected by varying the dipping time and even the substrate that is stainless steel 316L or alpha iron. This effect has been investigated using optical and scanning electron microscopy and diffusion mathematical laws. Hot-dip-aluminized alpha iron exhibits a tongue like interface growth and a thick interlayer with successively increasing dipping time, whereas in case of stainless steel 316l, the thickness of the interlayer decreases and the interface between the interlayer and the substrate successively becomes ‘smoother’. Micro Vickers hardness tester was used for testing hardness on three different areas of cross-sectional aluminized samples it was carried out on coating, inter-layer and on substrate. These results showed that the hardness of the interlayer was maximum as it contains the brittle intermetallic compounds formed during aluminizing process.