Development of an aluminized multi-phase steel with dual phase properties for high temperature corrosion resistance applications

A high strength, high Mn, Cr-Mo containing multi-phase steel grade was aluminized with a 90 wt% Al-10 wt% Si alloy coating, using a laboratory hot-dip simulator. The adhesion of the coating to the steel strip was evaluated and the microstructure of the as deposited material was assessed. The coated sheet steel was tested at high temperatures by monitoring the weight gain of the samples and their mechanical properties as a function of time. It was found that the thermal properties of the aluminized sheet were excellent. The analysis of the coating/substrate interface revealed the dissolution of brittle intermetallic phases, explaining the excellent high temperature resistance performance of the Al-Si coating up to temperatures as high as 900degreesC. In addition, the use of a continuous annealing cycle common in current aluminizing lines, resulted in a dual phase microstructure.