Chromizing of 3-Cr Steel

Steels with 3-Cr content are being evaluated as potential creep-resistant structural materials for steam plants.  There are concerns about the corrosion resistance of low-Cr steels at elevated temperatures, and it is likely that coatings will be necessary.   However, it is possible that coatings will degrade creep and fatigue resistance of the steel.  Thus, the influence of various coatings on the corrosion behavior and mechanical properties of creep-resistant steels needs to be evaluated. 

In this talk, aluminizing and chromizing of test coupons and mechanical test samples of 3-Cr steels coat will be discussed.    The coating method, i.e., halide activated pack cementation, will be described as well.  The effect of process parameters on the coating thickness, composition and microstructure will be pointed out.   Preliminary results of oxidation tests will be presented along with the relevant characterization of the coated coupons.