430 stainless round steel (ASTM A276; GB 10Cr17) has a composition of 16.0–18.0% chromium (Cr), ≤0.12% carbon (C), ≤1.00% silicon (Si), ≤1.00% manganese (Mn), ≤0.040% phosphorus (P), ≤0.030% sulfur (S), and no intentional nickel.
This differs sharply from 304, which contains 8.0–10.5% nickel. The lack of nickel has major chemical implications: 430 is a ferritic stainless steel (vs. austenitic for 304), meaning its microstructure is body-centered cubic (BCC) rather than face-centered cubic (FCC). This makes 430 more prone to brittleness at low temperatures (due to BCC's tendency to undergo ductile-brittle transition) and limits its formability compared to 304. Nickel also enhances 304's corrosion resistance by stabilizing the passive Cr₂O₃ layer; without nickel, 430's corrosion resistance is significantly lower-especially in chloride environments, where it is prone to pitting. 430's higher carbon limit (≤0.12% vs. ≤0.08% in 304) also increases the risk of intergranular corrosion if heated, as more carbon is available to form chromium carbides at grain boundaries. Chromium still provides basic oxidation resistance, but 430's chemical performance is clearly inferior to 304 in most aggressive environments.