These are theoretically non-magnetic and generally have good corrosion reisitance. Additional elements to Austenitic stainless are Nickel and Chromium with around 18% of Chromium and 8% of Nickel gives rise to the generic name 18/8 - however composition may vary widely from these figures.
303 - Free machining version of 304 with Suplhur added but less corrosion resistant. Not recommended for bending or welding.
304H - (Carbon 0.04% to 0.10%) gives improved creep resistance at elevated temperatures.
304L - (Carbon 0.03%) general purpose grade. Good for bending and welding. Corrosion resistant for most applications.
310 - High Chromium and Nickel content giving better heat resistance. Furnace applications. Maximum service temperature 1100 deg cel.
316L - (Carbon 0.03% Max) Molybdenum added for higher corrosion resistance. Food and marine applications. Good welding properties.
321 - Titanium bearing for good welding and heat resistance. Maximum service temperature 800 deg cel.
321H - (Carbon 0.04% to 0.10%) This alloy can be easily welded and has excellent resistance to corrosion and oxidation: has a high creep strength and works best up to 1600 degrees F
325 - Sulphur added free-machining version of 321. Not recomended for bending or welding.
These are magnetic and less corrosion resistant the the Austenitics. Weld poorly. Suitable for hardening and tempering. They are not susceptible to stress corrosion.
410 - General purpose grade. We normally stock in condition 'R'
416 - Sulphur added free machining version of 410. Kept in conditions 'P' or 'R'.
420 - Usually held in condition 'R' but higher Carbon allows higher hardness after heat treatment.
431 - We stock in high tensile condition 'T'. Higher Chromium and Nickel than other martensitics makes it more corrosion resisitant ( but not as good austenitic).