317 vs 316 Stainless Steel: Molybdenum-Boosted Alloys

 

How do their chemical compositions differ?​

316 contains 16-18% chromium, 10-14% nickel, 2-3% molybdenum, and 0.08% max carbon. 317 increases molybdenum to 3-4% and chromium to 18-20%, significantly boosting pitting resistance.​

 

Which provides better corrosion resistance?​

317 outperforms 316 in aggressive environments, including sulfuric acid, high-chloride solutions, and industrial waste. Its higher molybdenum content makes it more resistant to pitting and crevice corrosion.​

 

How do they compare in mechanical properties?​

Both have similar tensile strength (around 515 MPa) and ductility, with 317 offering slightly higher yield strength. They're equally formable and weldable, with 317 requiring no special techniques despite extra alloying.​

 

What are the cost and application differences?​

317 is 15-20% pricier than 316 due to extra molybdenum. It's used when 316's corrosion resistance isn't enough, such as in industrial waste treatment and aggressive chemical processing.​

 

Where are 317 and 316 commonly used?​

316 is in marine equipment and food processing machinery. 317 finds applications in chemical storage tanks, offshore oil rigs, and pulp and paper industry components.