Abstract
Chromizing is a suitable method for coating development for high temperature surface protection, corrosion and wear resistance. A homogenized dual phase Fe-24%Mn-8.3%Al-5%Cr-0.38%Si-0.34%Mo-0.45%C cast alloy was chromized with a pack cementation process at 1000 °C for 1-16 h. A chromized surface layer and an adjacent processing-related ferrite layer ranging from 80 to 100 μm in depth were formed. The thickness of the chromized layer X vs. the coating time t obeys the parabolic law: X=K√t, where K is evaluated to be 5.89 μm/ √h. The primary phase on the chromized surface is (Cr, Fe) 2 N 1 -× and the rest is Cr 23 C 6 , while the internal part of chromized layer is Cr 7 C 3 phase. An appreciable increase of the surface hardness ranging from 2015 to 2458 HK is achieved due to the formation of chromium carbide layer. A significant improvement of the corrosion resistance in 3.5 wt.% NaCl aqueous solution is obtained. Chromized specimens exhibit only one-tenth weight loss compared to uncoated specimens when immersed in 90% Na 2 SO 4 and 10% NaCl molten salt at 877 °C for 48 h. © 2002 Elsevier Science B.V. All rights reserved.