Dear Abedouahed

What is your question?.

If you want to improve the erosion-corrosion resistance of the Cr-cast alloy.Try to heat treat the alloy i.e.,at 80 C, for sometimes ,i.e., 1- 2 hours,in a vacuum furnace or an inerted- furnace to increase the passive layer of the alloy before testing the alloy for erosion-corrosion.

Dear Abedouahed,

for cast iron with 27% chromium, there is no difference between 20°C and 80°C. A least noticeable increase in the thickness of the oxide film (Cr2O3 passivation coating) on this alloy starts from approx 500 degrees, and this film will reach a thickness of about 1 micron at temperatures above 600°C. At this temperature, the surface of high chromium cast iron begins to acquire interference coloration, which indicates an oxide film thickness of 0.1 to 1 microns.

Dear Abdelouahed Chbihi ;

Agree with Vadim Verlotski, reply and adding that this alloy has high corrosion resistance, the high chromium content improved its corrosion resistance and combined erosion-corrosion resistance over those with lower alloy chromium content. Although Ni-resist irons showed good corrosion resistance to many environments and are frequently used, they lack sufficient mechanical strength and suitability at a service temperature higher than (800 °C) [10]. Moreover, a new type of high chromium cast iron with 0.38% nitrogen (HCCI-N) was fabricated by vacuum induction is more resistant at high temperature. more details in the following references;

https://www.sciencedirect.com/science/article/abs/pii/S0043164821000442

Article Wear and Corrosion Behavior of High-Cr White Cast Iron Alloy...