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.
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.
