Application Difference Between SS316 & SS316L

316L carries low carbon content (0.030 %) as compared to 316 (.08 %). Hence tendency to lose Chromium (which helps in resisting corrosion) via formation of Chromium Carbide is more in 316 than in 316L due to higher carbon content. So SS316L is used in place of SS316 in those excessively corrosive environments where intergranular corrosion of welds and heat affected zones is expected.

The application difference between Stainless steels 316 & 316L is as follows:

☺ 316

Good for:

• Good resistance to a wide range of chemicals - generally somewhat better than 304.

• Useful resistance to Chlorides, especially if cold - safe sea water temperature 22^oC.

• Higher resistance to pitting and crevice corrosion than 304 - PREN = 24.

• Excellent formability - readily deep drawn, bent and forged hot or cold.

• Available in an Improved Machinability "Ugima" form.

• Excellent weldability

• Useful high temperature strength to 870^oC - higher hot strength than 304.

Not Good for:

• Poor resistance to stress corrosion cracking - susceptible above 60^oC in even low Chloride environments. No better than 304 - use 2205 instead.

• Not suitable for exposure to hot concentrated nitric acid - 304 is better.

• Reduced scaling resistance in some environments above about 500^oC, due to Molybdenum.

• Low strength, particularly proof stress, limits structural use.

☺ 316L

Good for:

• Same good general corrosion resistance as Grade 316.

• Low Carbon (generally 0.03% max) gives resistance to sensitization for use in temperature range 450-850^oC and in heavy section welding (over about 5–10mm thick).

• Low Carbon content also reduces work hardening rate slightly - improves ductility for cold forging, drawing etc.

Not Good for:

• Lower hot strength than 316 - design codes limit use to about 500^oC maximum. This limit also applies to nominal Grade 316 with less than 0.03% Carbon.

• Same local corrosion resistance as 316, so poor resistance to stress corrosion cracking in Chloride environments - limit about 60^oC.

Grade 316 is the standard molybdenum-bearing grade with good overall corrosion resistant properties, particularly higher resistance to pitting and crevice corrosion in chloride environments. Continuous use of 316 in the 425-860°C range is not recommended if subsequent aqueous corrosion resistance is important. It has excellent forming and welding characteristics. It is readily brake or roll formed into a variety of parts for applications in the industrial, architectural, and transportation fields. Grade 316 also has outstanding welding characteristics. Post-weld annealing is not required when welding thin sections however heavy welded sections require post-weld annealing for maximum corrosion resistance.. Grade 316L, the low carbon version of 316 and is immune from sensitisation (grain boundary carbide precipitation). Thus it is extensively used in heavy gauge welded components (over about 6mm) and no post-weld annealing required. Grade 316L being more resistant to carbide precipitation can be used continuously in above temperature range. Typical applications include: - Food preparation equipment particularly in chloride environments. - Laboratory benches & equipment. - Coastal architectural panelling, railings & trim. - Boat fittings. - Chemical containers, including for transport. - Heat Exchangers. - Woven or welded screens for mining, quarrying & water filtration. - Threaded fasteners. - Springs.