What Makes Grade 317 SS Different from 304 & 316 SS?

Grade 304, 316, and 317 stainless steel are all considered austenitic stainless steel alloys. These alloys all share some similar properties, such as high strength, corrosion resistance, and high concentrations of chromium and nickel.

What separates 316 and 317 SS from 304 SS is that these higher-numbered alloys have added molybdenum in their formulation—grade 316 has about 2-3% molybdenum, and grade 317 has more than 3% molybdenum.

This added molybdenum greatly improves the steel’s resistance to pitting from chlorides, which is why grade 316 SS is often used in the chemical processing and marine industries.

However, this added molybdenum content also influences the cost of these two alloys. Grade 317 SS is generally more expensive than grade 316 SS. 316 SS, in turn, is more expensive than grade 304 SS. The exact extra cost varies based on the market at the time.