The primary reason why 316 stainless steel is more expensive than 304 stainless steel comes down to the cost of its alloying elements, specifically molybdenum and slightly higher nickel content.

Here’s a breakdown of the factors contributing to the higher cost of 316 SS:

1. Molybdenum Content: This is the most significant factor. 316 stainless steel contains approximately 2-3% molybdenum, while 304 contains only trace amounts, if any. Molybdenum is a relatively expensive alloying element compared to iron or chromium. Its addition is precisely what gives 316 its superior resistance to pitting and crevice corrosion, especially in chloride environments. The cost of adding this specific element directly increases the raw material cost.
2. Nickel Content: 316 stainless steel typically requires a slightly higher minimum nickel content (around 10-14%) compared to 304 (around 8-10.5%). Nickel is also a relatively expensive alloying metal, and its price fluctuates significantly on the global market. This higher nickel requirement further adds to the material cost of 316.
3. Market Demand and Supply: While both 304 and 316 are widely used, the specific demand dynamics for molybdenum and higher-nickel alloys can influence pricing. However, the fundamental driver remains the intrinsic cost of the alloying elements.
4. Processing Costs (Minor Factor): While processing costs for both grades are broadly similar as they are both austenitic stainless steels, slight differences in work hardening behavior or specific mill requirements could theoretically have a minor impact, but this is generally overshadowed by the raw material costs.

In essence, you are paying for the enhanced performance, particularly the significantly improved corrosion resistance, that the molybdenum and increased nickel provide in 316 stainless steel. The higher price reflects the higher cost of incorporating these valuable alloying elements into the steel matrix.