Heat treatment and effects of Cr and Ni in low alloy steel

The effects of Cr and Ni on low carbon steel was observed. Undissolved carbide particles refine the austenite grain size. In the presence of nickel, chromium carbide is less effective in austenite grain refinement than chromium carbide in absence of nickel at temperature below 975°C. Nickel does not produce any austenite grain refinement but presence of nickel promotes the formation of acicular ferrites. It was also found that Ni and Cr as chromium carbide also refines the ferrite grain size and morphology. Cr as chromium carbide is more effective in refining ferrite grain size than nickel.