SUS 316 Forgings (JIS G4303 / UNS S31600 / EN 1.4401)

We melt and open-die forge SUS 316 to customer drawings at our works in Jiangyin, Jiangsu. Forms include seamless rolled rings, forged flanges, shafts, round bars, discs, tube sheets, sleeves, bushings and valve parts, supplied solution annealed with EN 10204 3.1 or 3.2 certification.

Data checked against JIS G 4303, ASTM A240 and ASTM A182. Updated 3 October 2026.

What SUS 316 is

SUS 316 is the Japanese Industrial Standard name for the molybdenum-bearing austenitic stainless steel sold elsewhere as Type 316, UNS S31600 and EN 1.4401. It is SUS 304 with 2 to 3% molybdenum added, and that addition is the whole reason the grade exists. Molybdenum gives 316 better overall corrosion resistance than 304 and, in particular, higher resistance to pitting and crevice corrosion in chloride environments. After 304 it is the most used austenitic stainless steel.

The austenitic structure brings excellent toughness, held down to cryogenic temperatures, along with excellent forming and welding behaviour. Like every austenitic stainless, SUS 316 cannot be hardened by thermal treatment. Strength comes from the chemistry and from cold work, not from a quench.

Which standard are you buying to?

SUS 316 on its own is a chemistry, not a product specification, and the acceptance values shift with the standard named on the order. A ring bought as JIS G 4303 bar stock, as ASTM A182 F316 forgings or as JIS G 3214 SUS F316 pressure-vessel forgings carries the same chemistry but different minimum elongation and hardness limits.

Elongation. A182 F316 asks for 30% elongation and 50% reduction of area, not the 40% quoted for bar and plate. The lower figure allows for heavier sections and for test pieces cut across the grain flow. If a drawing calls out 40% on a large forged ring, tell us at enquiry stage so the test-piece location and the forging reduction ratio can be planned around it.

Chemical composition of SUS 316

Watch the silicon limit. JIS G 4303 and A182 F316 both allow silicon to 1.00%; A240 plate stops at 0.75%. A heat that is sound as SUS 316 bar can fail an A240 product analysis on silicon alone. We aim the ladle at the tightest limit written on the order, which is one practical benefit of melting the steel in the same works that forges it.

Melting route

SUS 316 is melted in our 25 t electric arc furnace, refined in a 25 t or 50 t ladle furnace, then decarburised under vacuum in a 30 t or 60 t VOD unit. VOD is what pulls carbon down reliably and keeps nitrogen and residuals in hand, which matters for 316 and is not optional for 316L. Maximum heat size is 60 tonnes. Electroslag remelting in our 3 t or 6 t protective-atmosphere furnaces is available where a specification demands tighter cleanliness, though standard SUS 316 rarely calls for it.

Physical properties

Corrosion and heat resistance

SUS 316 performs excellently across a wide range of atmospheres and many corrosive media, generally better than 304. Its limits are well mapped, and worth stating plainly, because the grade gets specified past them more often than any other stainless we forge.

Chlorides and stress corrosion cracking

316 pits and suffers crevice attack in warm chlorides, and it cracks under stress corrosion above roughly 60 °C. It is taken as resistant to potable water with up to about 1000 mg/L chlorides at ambient temperature, falling to about 500 mg/L at 60 °C. The grade is usually called the standard marine stainless, but it is not resistant to warm sea water, and in many marine settings it stains brown at crevices and on rough surface finishes.

Its pitting resistance equivalent, PREN = %Cr + 3.3 × %Mo + 16 × %N, lands at roughly 24 to 26. That covers light coastal exposure. It does not cover submerged service, crevice-heavy assemblies or high-chloride process duty. Where the duty runs past it, see the alternative grades below.

Elevated temperature

Oxidation resistance is good to 870 °C intermittent and 925 °C continuous. Continuous service between 425 and 860 °C is not advised where aqueous corrosion resistance still matters afterwards, because carbide precipitation in that band sensitises the steel. For parts that must sit in that range and then resist wet corrosion, specify 316L. For parts carrying load above about 500 °C, 316H has the elevated-temperature strength and brings a grain-size requirement of ASTM No. 7 or coarser.

Forging practice, heat treatment and machining

Solution annealing

Solution treatment means heating to 1010-1120 °C and cooling fast, to put chromium carbides back into solution and leave a fully austenitic structure. The cooling rate through the sensitising band decides whether that is achieved, so on heavy rings and thick discs the section thickness and the quench tank govern the result as much as the furnace setting. There is no quench-and-temper route for raising strength here; the grade does not respond to it.

Our heat-treatment shop runs 14 furnaces. Car-bottom furnaces take work to 8,000 × 2,000 × 2,000 mm, and two well furnaces 15 m deep let long SUS 316 shafts be solution treated and quenched vertically, which avoids the bow that comes from quenching a long shaft on its side.

Welding

316 welds well by all standard fusion methods, with or without filler, and thin sections need no post-weld anneal. Heavy welded sections in 316 do need post-weld annealing for full corrosion resistance. 316L does not, which is the usual reason it wins for welded components over about 6 mm; 316Ti is the other option in heavy section.

Machining

316 machines like any austenitic stainless. It work hardens, it is gummy, and it wants sharp tooling, rigid setups and plenty of coolant. An improved-machinability version of the grade exists in round and hollow bar, giving higher cutting rates and lower tool wear, but that is a mill product rather than something produced from a forged ingot. We supply forgings as-forged with allowance, proof-machined for ultrasonic inspection, or finish-machined to drawing on vertical lathes to 5,000 mm swing and horizontal lathes to 14 m between centres.

SUS 316 equivalent grades

Equivalence is approximate. These are functionally similar materials, not contractual equivalents, and the limits differ between standards, as the silicon case above shows. Where an exact equivalent is required, the original specification has to be consulted and named on the order. We certify to the specification you name, not to a cross-reference table.

316, 316L and 316H

316 and 316L are often stocked dual certified, meeting both at once. Dual certified material does not meet 316H and may be unacceptable at high temperature, so do not accept a 316/316L certificate against a 316H line item.

When SUS 316 is not enough

SUS 316 product forms we forge

Size envelope for SUS 316. Heaviest single forging 30 tonnes, largest rolled ring OD 6,000 mm, smallest ring OD 50 mm by the upset-and-punch route, longest turned shaft 14 m, minimum order 10 kg with no minimum piece count.

Where SUS 316 forgings are used

316 gets specified where 304 is marginal on corrosion but the service does not yet justify duplex or a nickel alloy. Typical uses for the grade include food preparation equipment in chloride environments, laboratory benches and equipment, coastal architectural panelling, railings and trim, boat fittings, chemical containers including transport tanks, heat exchangers, woven and welded screens for mining, quarrying and water filtration, threaded fasteners and springs. In forged form, these are the jobs we are asked for most.

Testing, inspection and certification

Because the steel is melted here, chemistry is verified at the furnace rather than inherited from someone else's billet certificate, and traceability runs from melt number through forging, heat treatment and machining to the shipped part.

The works holds CCS, BV, DNV, LR and NK approvals. Heat-treatment charts, NDT reports, dimensional reports and PMI records go out with the certificate. Intergranular corrosion testing to ASTM A262 is the item most often left off a 316 order and most often demanded at the point of inspection, so put it on the enquiry and it gets scheduled before shipment instead of after.

Request a quotation for SUS 316 forgings

Quotations come from a drawing or a written specification, normally back within two working days of a complete enquiry. Minimum order is 10 kg with no minimum piece count. Lead time for SUS 316 sits at the lower end of our 20 to 60 day range, since the grade runs through the EAF and VOD route with no remelting step.

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Frequently asked questions about SUS 316

Related grades and product pages

Austenitic and higher-alloy stainless grades we forge: A182 F316, A182 F321, A182 F347, A182 F309, 904L, Sanicro 28, Nitronic 50, Nitronic 60, A182 F44, A182 F51, A182 F53, A182 F55.