Evolution of Al-Si Coating Microstructure during Heat-Treatment of Usibor^® 1500

Microstructural evolution of Al-10wt.%Si-(2-3)wt.%Fe coating during heat-treatment processing of the press hardenable steel Usibor^® 1500 was studied experimentally. Two coating thicknesses, AS150 (60-100 g/m2) and AS80 (35-65 g/m2), were subjected to the same heat-treatment schedule. The interrupted experiments were performed at heating and soaking stages in order to track the microstructural evolution. The effects of heating rates (and steel substrate thickness) on evolution of the coating were researched as well. Furthermore, the experimental results of coating development were then compared with the results of analytical modelling. (paper)