Nitrogen is also an element that forms austenite, which can partially replace nickel, and the ratio of nitrogen to nickel is 0.025~1. However, due to the relatively low solubility of nitrogen in the steel weight, some people think that the nitrogen content in the steel exceeding 0.25% will cause pores in the ingot; some people think that the chemical composition of the steel should be adjusted accordingly, especially the content ratio of chromium and manganese.
When appropriate, good quality ingots can be obtained even with a nitrogen content of 0.65%. The effect of a single pair on the formation of austenite is significant. For example, 18-8 type chromium-nickel steel, when it contains 0.15%, needs 5% nickel to obtain austenite structure; when it contains 0.25% nitrogen, only 4.5% nickel is needed. In order to save nickel, chromium-manganese-nitrogen stainless steel, which replaces nickel with manganese and nitrogen, has been used to some extent.
