Influence of Nitrogen on Chromium Cast Iron Structure and Properties

Structural and phase compositions of castings of chromium cast irons ChKh32 (2-4% C; 30% Cr; 2.4% Mn; 0.6% Si) alloyed with nitrogen using nitrided chromium as a master alloy are studied by X-ray diffraction, metallographic analyses, and scanning electron microscopy methods. It is shown that nitrogen in cast iron obtained is present mainly in iron-based solid solution, along with chromium, manganese and carbon, and is partly included within the composition of carbide phase (Fe, Cr)(7)C-3. Nitrogen alloying of ChKh32 (2% C) stabilizes austenite. Nitrogen alloying of ChKh32 (3-4% C) followed by heat treatment leads to formation of an austenitic-martensitic structure with an increase in material hard-ness. It is shown that addition of nitrogen in an amount of 0.2% to ChKh32 (2% C) improves corrosion resistance, and an increase in carbon content in these materials increases abrasive wear resistance.