Type 316 stainless steel
Selecting UNS S31600 by product form, condition and exposure, with distinctions from 316L and bounded property and corrosion evidence.
Tags: materials, stainless-steel, austenitic
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Identity and product specification
ATI lists 515 MPa minimum tensile and 205 MPa minimum yield for Type 316 plate alongside ASTM A240 and ASME SA-240. Its bulletin gives 0.08% maximum carbon for 316 versus 0.030% for 316L. The lower carbon helps with intergranular attack after short thermal exposure such as welding. ATI reports no corresponding benefit for chloride stress-corrosion cracking. ATI plate data, ATI 316/316L bulletin
Type 316, UNS S31600, is an austenitic chromium-nickel-molybdenum stainless steel. ATI's product page lists chromium 16–18%, nickel 10–14%, molybdenum 2–3% and carbon 0.08% maximum, with other controlled elements. Selected composition limits do not replace the complete ordered specification or delivered heat analysis. ATI 316 product identity and chemistry
Outokumpu identifies Supra 316/4401 (EN 1.4401) and Supra 316/4436 (EN 1.4436) as separate offerings associated with S31600. Its range also contains 316L, 316Ti and 316plus products with different identities. Preserve the full designation and producer product instead of treating every name containing “316” as interchangeable. Outokumpu Supra range composition and designations
Type 316 versus 316L
ATI's technical bulletin distinguishes the 0.08% maximum carbon of 316 from 0.030% maximum for 316L. It discusses lower-carbon material where welding and subsequent exposure make intergranular corrosion important. This is a condition-specific selection issue, not permission to substitute one grade for another without checking all ordered requirements. ATI 316/316L technical bulletin
Keep carbon limits separate from mechanical acceptance, code allowances and service qualification. A low-carbon designation alone cannot establish joint efficiency, allowable stress or compliance of a finished vessel or device. Record the applicable specification and final condition, including any required heat treatment.
ATI explicitly says that the low-carbon variants offer no advantage for chloride stress-corrosion-cracking resistance, despite their benefit where intergranular corrosion is a concern. Do not collapse those mechanisms into one generic corrosion rating. ATI intergranular-corrosion and SCC discussion
Bounded mechanical and mass examples
ATI's plate product listing publishes these entries alongside ASTM A240 and ASME SA-240:
| Quantity | Published plate entry |
|---|---|
| Tensile strength | ≥515 MPa |
| Yield strength | ≥205 MPa |
| Elongation | ≥40% |
| Hardness | ≤95 HRB |
The web summary does not give a complete temperature, orientation and specimen protocol beside the table. Confirm those details, condition and applicable dimensional limits in the governing order before using the entries for acceptance or calculation. They are not universal properties of every S31600 form. ATI plate specifications and properties
Keep minimum requirements, typical characterization and shipment test results in separate fields. A favorable measured tensile result does not establish a minimum for future supply, and no tensile figure alone establishes fatigue life, allowable pressure or impact performance.
ATI lists density 8.03 g/cm³. An ideal 100 × 100 × 2 mm solid sheet occupies 20 cm³, giving estimated mass 160.6 g. This original calculation excludes holes, coatings, fasteners, tolerances and density variation. Use finished geometry and a suitable material input for a final mass model. ATI density basis
A mass comparison does not establish equal stiffness or stability after changing material or thickness. Reassess support, joints, local geometry and load history separately.
Corrosion evidence and exposure definition
Outokumpu presents pitting-resistance-equivalent values as a rough comparison based on composition, and distinguishes pitting, crevice corrosion, SCC and intergranular attack. Its Supra 316/4401 table gives PRE 24, while the higher-molybdenum 316/4436 offering has PRE 25. Neither number is a corrosion rate, service-temperature limit or acceptance test for a finished component. Outokumpu corrosion guidance and PRE table
The same guide warns of chloride-induced SCC under combined tensile stress, chloride exposure and temperatures above about 50°C. This is screening guidance, not a guarantee that all conditions below a single temperature are safe. Its pitting/crevice discussion also makes chemistry and surface state part of selection. Outokumpu localized corrosion and SCC
Describe fluid composition, concentration, contaminants, pH, oxidants, temperature, aeration, flow, deposits, crevices and stress. Include cleaning, shutdown and upset conditions. Specify the acceptable general-corrosion rate and localized-attack criteria before choosing supporting tests.
For a gasket, fastener or dissimilar-metal interface, assess the assembled geometry. Open-surface evidence does not settle an inaccessible crevice. Where the intended exposure differs from published data, obtain producer advice or representative testing instead of assigning a universal seawater or chloride rating.
Thermal history, welding and finishing
ATI describes chromium-carbide precipitation and sensitization after exposure of 316 in the 427–816°C range. The relevant risk depends on exposure and subsequent environment; the range is not a complete time–temperature service envelope. ATI sensitization discussion
Define the starting condition, forming, joining, thermal treatment and final acceptance before production. An unspecified instruction to stress relieve can leave both the intended mechanical state and corrosion performance unresolved. A hardness reading cannot reconstruct the full thermal history.
ATI's welding guidance calls for clean surfaces and proper inert shielding and warns that carbon-steel brushes can embed particles that subsequently rust. ATI welding and cleaning guidance
Qualify the actual joint, filler, shielding, thermal controls and inspection. Establish the required properties and cleanliness in weld and heat-affected regions separately from incoming stock. Define post-weld surface acceptance rather than treating a bright appearance as proof of corrosion resistance.
Plan machining and forming around the supplied condition, tooling, work hardening, springback and required finish. Use representative trials for critical features. For another manufacturing route, including casting or additive manufacture, obtain route-specific properties and qualification instead of transferring wrought plate entries.
Release and source versions
Retain the specification, producer, heat/lot, certificate, supplied and final conditions, drawing, fabrication history and inspection results together. Resolve substitutions against the complete service and acceptance record. Application lists identify candidates and do not qualify a particular pressure boundary, food-contact assembly or implant.
ATI's bulletin prints Version 1, 18 April 2012. Outokumpu's Supra PDF prints 1561EN:4, November 2022. The live ATI page has no technical revision date used here. These are reference-document identities, not evidence of current contractual specification editions. Review date: 2026-11-01, America/Los_Angeles.