Scope
UNS S31600 is the Unified Numbering System designation for the molybdenum-bearing 316 austenitic stainless steel that ASTM A193 Grade B8M is manufactured from. The same chemistry envelope appears across multiple international standards under different designations; this page consolidates the cross-references and the procurement-relevant material data for sourcing 316 SS bolting from any regional supply chain.
International designations
- UNS (Unified Numbering System, US): S31600 (standard 316), S31603 (316L low-carbon variant)
- AISI (American Iron and Steel Institute): Type 316, Type 316L
- ASTM A193 / ASME SA-193 (US bolting): Grade B8M, Grade B8MA, Grade B8MN (high nitrogen), Grade B8MLCuN (super-austenitic variant)
- ASTM A194 / ASME SA-194 (companion US nut): Grade 8M, Grade 8MA
- EN 10088-3 (European stainless steel): 1.4401 (316), 1.4404 (316L)
- DIN W.Nr (German Werkstoffnummer): 1.4401 (X5CrNiMo17-12-2)
- JIS G4303 (Japan): SUS 316, SUS 316L
- GOST 5632 (Russia): 08Kh17N13M2T (316Ti equivalent), 03Kh17N14M3 (316L equivalent)
- GB/T 1220 (China): 0Cr17Ni12Mo2 (316), 00Cr17Ni14Mo2 (316L)
- BS 970 (UK legacy): 316S31, 316S11 (316L)
Physical properties
Typical 316 stainless steel physical properties at room temperature (not specified-minimum, engineering reference values):
- Density: 8.00 g/cm³ (0.289 lb/in³)
- Modulus of elasticity: 193 GPa (28.0 × 10&sup6; psi) at 20°C
- Mean coefficient of thermal expansion (20-100 °C): 16.0 × 10⁻⁶ /°C (8.9 × 10⁻⁶ /°F)
- Thermal conductivity (100°C): 16.3 W/(m·K)
- Electrical resistivity (20°C): 0.74 µΩ·m
- Specific heat (20°C): 500 J/(kg·K)
- Melting range: 1370-1400°C (2500-2550°F)
- Magnetic permeability (annealed): μr ≈ 1.02 (essentially non-magnetic; rises slightly in strain-hardened Class 2 condition due to martensite formation under cold work)
Fabrication and welding notes
316 stainless steel work-hardens significantly during machining; threading is generally cut rather than rolled at large diameters to avoid excessive thread-root hardness. Tooling, feeds, and speeds should follow austenitic stainless guidelines (rigid setups, sharp tools, generous coolant). Welding is performed with matching filler metals (ER316L or ER316LSi for 316L base, ER316 for standard 316) following the AWS A5.9 envelope; the L-grade filler is preferred for sensitization-prone welds. Post-weld solution annealing restores the Class 1 / Class 1A microstructure for sour-service applications.
Service-temperature guidance
Class 1 / Class 1A / Class 1D solution-annealed B8M is stable in service up to roughly 800°F (425°C) without creep relaxation. Class 2 strain-hardened B8M is limited to the same temperature ceiling and is not preferred above 400°F for sustained service because thermal recovery of the cold-worked structure reduces yield strength over time. The low-temperature lower limit is −425°F (−254°C) for cryogenic service across all classes, with Charpy impact retention typical of austenitic stainless steel.
B8M Equivalent Grades (DIN / EN / JIS / GB / BS)
UNS S31600 is the single most cross-referenced austenitic stainless steel in the global standards landscape. The same nominal Cr 17 percent, Ni 12 percent, Mo 2.00 to 3.00 percent, C 0.08 max chemistry is catalogued under at least eight national systems. A buyer placing a B8M purchase order against a project specification written to EN, DIN, JIS, GB, or BS nomenclature can rely on the mapping below to confirm the material grade is identical at the heat-analysis level. Mill certification routinely cross-stamps multiple grade names on the same 3.1 / 3.2 certificate per EN 10204.
| Standards system | Designation equivalent to A193 B8M (UNS S31600) | Issuing body |
|---|---|---|
| ASTM (USA) | A193 Grade B8M / A194 Grade 8M / A182 F316 | ASTM International |
| ASME BPVC (USA) | SA-193 Grade B8M / SA-194 Grade 8M | American Society of Mechanical Engineers, Section II Part A |
| AISI / SAE (USA) | Type 316 | American Iron and Steel Institute (legacy designation) |
| UNS (USA) | S31600 | SAE / ASTM Unified Numbering System |
| EN 10088-3 (Europe) | 1.4401 (X5CrNiMo17-12-2) | European Committee for Standardization (CEN) |
| DIN (Germany, legacy) | X5CrNiMo17-12-2 / Werkstoff 1.4401 | Deutsches Institut fur Normung |
| BS EN 10269 (United Kingdom) | 1.4401 condition AT (solution annealed) | British Standards Institution |
| JIS G 4303 (Japan) | SUS 316 | Japanese Industrial Standards |
| GB / T 1220 (China) | 06Cr17Ni12Mo2 (legacy designation 022Cr17Ni12Mo2) | Standardization Administration of China |
| ISO 3506-1 (international fasteners) | Property class A4 (with A4-70 / A4-80 tensile classes) | International Organization for Standardization |
| NF AFNOR (France, legacy) | Z6CND17-11 / Z6CND17-12 | Association Francaise de Normalisation |
| GOST (Russia) | 08Kh17N13M2T / 08H17N13M2T | Russian state standard (closest equivalent, Ti-bearing variant) |
Field substitution between any two of the above grades on the same B8M order is routine and accepted by every major end-user spec (Shell DEP, BP GIS, ExxonMobil GP, Aramco SAES, Total GS), subject to engineer-of-record approval and a 3.1 mill certificate showing the equivalent grade designation alongside the ordered ASTM A193 grade. The European A4-70 designation matches A193 B8M Class 1 (75 ksi tensile, solution annealed), while A4-80 maps to a strain-hardened condition closer to B8M Class 2. Below A4-70 the EN tensile class is outside the A193 envelope.
Related references
Detailed pages: B8M overview, B8M Class 1, Class 1A, Class 1D, Class 2, B8M vs B8 (316 vs 304), ASME SA-193 designation. Companion hardware: ASTM A194 Grade 8M nuts.
