Stainless Steel Grade 316 – Austral Wright Metals
Product Data Sheet – Stainless Steel
Grades 316, 316H UNS-S31600, S31603, S31609
Stainless Steel Grade 316 is the second most commonly used stainless steel. It is an austenitic, corrosion resistant steel with excellent strength, toughness, fabrication characteristics and weldability. The low carbon version, 316L, may be required for full corrosion resistance when thicker sections are welded. The 316H version has a guaranteed minimum carbon content, which ensures good strength at high temperatures.
Brewing and dairy equipment, evaporators, drums, barrels, heat exchangers, chemical and food processing, water treatment plant, chemical processing equipment, architectural and boat fittings exposed to marine and polluted atmospheres.
(AS1449 / ASTM A240 – Flat Products)
(AS1449 / ASTM A240 – Flat Products)
Grade 316 is a member of the 18/8 chromium nickel family of austenitic stainless steels, with an addition of 2% molybdenum for improved corrosion resistance, particularly to localised corrosion in chloride containing environments. The very tough and ductile austenitic structure gives grade 316 excellent formability and fabrication characteristics.
In most applications the steel is used where its corrosion resistance gives long lasting service life and appearance. The ease of cleaning and of maintaining a hygienic surface on the steel make it excellent for many purposes.
The low carbon version, 316L, may be required for full corrosion resistance when sections thicker than about 5 mm are welded. The version with guaranteed high carbon, 316H, may be required for elevated temperature service, such as pressure vessels.
Austral Wright Metals can supply this grade as plate, coil, sheet, strip, round, hexagon, flat bar, angles, tube, pipe and welding consumables.
No1 (hot rolled, annealed and pickled), 2D (cold rolled), 2B (cold rolled, skin passed), N4 (polished).
Flat products are available surface protected with white polyethylene (PE) film. Protection with blue poly vinyl chloride (PVC) for deep drawing or black PVC (for heavy forming) is also available.
Grade 316 has excellent corrosion resistance in many environments. Austral Wright Metals will be pleased to provide advice for specific applications.
Grade 316 gives good service in atmospheric conditions, resisting most environments. It is often used in marine conditions, or where industrial pollution is heavy. Best appearance is maintained where the design allows even rain washing of the surface, or where dirt deposits are occasionally washed off the steel.
Grade 316 has given excellent service in potable water. Pitting and crevice corrosion may occur in waters with higher chloride content, and 2000 ppm is accepted as the upper limit. The higher molybdenum content of 316 make it significantly more corrosion resistant than grade 304.
Grade 316 can be used with seawater, provided precautions are taken to avoid crevice corrosion developing under sediments, precipitation and biofouling, and at designed-in crevices.
Grade 316 (and grade 304) may suffer stress corrosion cracking in solutions containing chloride ions at temperatures over about 60°C. Stress corrosion cracking should be considered for all corrosion services where the corrosive liquid may contain chloride.
Austenitic stainless steels are inherently tough, maintaining the ductile fracture mode and high absorbed energy in impact tests to cryogenic temperatures (-200°C).
AS1210, Pressure Vessels, allows the use of grade 316 up to a temperature of 800°C. The standard allows the use of higher design stresses for 316H at all temperatures.
High Temperature Corrosion
The generally accepted maximum service temperatures for grade 316 (and grade 304) in air are 870°C for intermittent service and 925°C for continuous service.
Grade 316 is readily workable, by the standard methods of sheet metal working, with the exception that it cannot be oxygen cut. Plasma cutting is normal. The deep drawing capability of grade 316 is outstanding, because of its high austenite stability.
316 is one of the easier austenitic stainless steels to forge, at temperatures above 925°C.
Grade 316 is relatively easy to machine, although more difficult than carbon steel. More power is required to machine grade 316. Cutting speed should be lower, the feed higher, tooling and equipment heavier. The machinability of 316 is about 60% that of AISI B1112 resulphurised free cutting carbon steel. A free machining version of 316 is available as bar.
Solution annealing is performed at 1065 – 1120°C, followed by rapid cooling to prevent the precipitation of the chromium carbides. 316 cannot be hardened by heat treatment. Stress relieving is rarely required due to the high ductility of 316.
Grade 316 is readily weldable by most fusion techniques (GTAW / TIG, GMAW / MIG / MAG, MMAW / stick, SAW), with no preheat, postheat or control of interpass temperature needed. It is usually welded with filler metals of the same grade, 316 or 316L (or the silicon containing versions) which retains corrosion resistance and strength. These grades are pre-qualified weld metals to AS1554.6:1994 for welding grade 316 to itself.