5Cr9Si3 is a new medium-carbon martensitic valve steel. Compared to traditional valve steels like 4Cr9Si2, 5Cr9Si3 boasts a higher carbon content, resulting in excellent hardenability. The combination of silicon and chromium in the steel also enhances its oxidation and corrosion resistance. 5Cr9Si3 offers a high cost-performance ratio and has been successfully used in the manufacture of engine intake valves, although its current domestic market usage is relatively low.