Comparator
Two grades, side by side, including where each one fails.
Up to four at a time. The limitations row is the one that matters — every supplier publishes strengths, which is why strengths alone never settle a specification.
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FAQ
04Selecting a grade
- What is the difference between 304 and 316?
- 316 contains 2 to 3 percent molybdenum, which 304 does not. That improves resistance to pitting and crevice corrosion in chloride environments, which is why 316 suits marine, chemical and coastal service. For dry indoor, food and general water use, 304 performs well at lower cost.
- What is duplex and super duplex stainless steel?
- A duplex microstructure is roughly half austenite and half ferrite, giving about double the yield strength of 316L together with much better resistance to chloride stress corrosion cracking. Super duplex (for example 2507) pushes corrosion resistance further for seawater and sour service. The main limit is a maximum service temperature near 300 degrees Celsius.
- What does PREN mean?
- PREN is the Pitting Resistance Equivalent Number: percent chromium plus 3.3 times percent molybdenum plus 16 times percent nitrogen. Higher means better resistance to pitting in chlorides. It is a ranking figure, not a substitute for assessing a specific service condition.
- Which grade should I choose?
- It depends on the medium, temperature and pressure the material will see. Our grade pages and the grade comparator set out composition, corrosion behaviour and limitations side by side; if you tell us the service conditions, we will tell you what we would specify.
Still deciding?
Tell us the medium, temperature and pressure. We will tell you what we would specify — and what we actually hold.