Stainless Steel 316F
AISI/SAE 316F · UNS S31620
316F (UNS S31620) is a free-machining version of 316 austenitic stainless steel in which deliberate sulfur (and sometimes higher phosphorus) additions form manganese-sulfide inclusions that break up chips and dramatically improve turning and automatic-lathe productivity.
Values for the Cold Drawn condition
316F tempers and conditions
316F is supplied in 3 conditions, soft to hard. Cold Drawn is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
solution annealed (~1040–1120 °C, rapid cool) | Pick for maximum ductility, best available corrosion resistance and any forming or bending of the bar. | 260 | 550 | 45 | 160 HB | — |
Cold DrawnDefault annealed then cold drawn bar (as-drawn, unground) | Standard stocked screw-machine bar: higher strength, tighter tolerance and cleaner chip-breaking than annealed. | 450 | 620 | 30 | 200 HB | — |
heavily drawn small-diameter bar/wire | Pick for small-diameter shafts and fasteners needing higher yield strength, accepting low ductility and magnetism. | 620 | 760 | 15 | 21 HRC | 2.3 % IACS |
What is 316F?
316F (UNS S31620) is a free-machining version of 316 austenitic stainless steel in which deliberate sulfur (and sometimes higher phosphorus) additions form manganese-sulfide inclusions that break up chips and dramatically improve turning and automatic-lathe productivity. It keeps the Cr-Ni-Mo base of 316, so general and chloride-pitting resistance is still good for a free-machining grade, and it is chosen for high-volume screw-machine parts, valve components and fittings. The sulfides, however, reduce corrosion resistance versus standard 316, sharply degrade weldability (hot-cracking) and lower transverse ductility and polish quality. 316F has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,375°C (2,507 °F). 316F has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 70% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 193 GPa (28 Msi).
What is 316F used for?
- Marine machined fittings
- Surgical hardware
- Screw-machine valve components
- Pump and instrument shafts
- Threaded fasteners and inserts
- Hydraulic fittings and adapters
- Bushings and spacers
Advantages
- Easy to machine — 72/100, better than 99% of stainless steel grades
Limitations
- Hard to polish — 45/100, worse than 96% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
316F properties
Typical room-temperature values for 316F-Cold Drawn; bars are the position among stainless steel grades.
Physical3
316F has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,375°C (2,507 °F).
Mechanical13
316F has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 70% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
316F is rated for continuous service to 700°C (1,292 °F). It conducts heat at 16.3 W/m·K (9.42 BTU/hr·ft·°F), better than 68% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
316F conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of 316F takes about 55 MJ of energy and emits 5.2 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
316F's machinability is very good (72/100, better than 99% of stainless steel grades); weldability poor (25/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 316F is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 316F
Is 316F easy to machine?
Runs well on multi-spindle and CNC lathes at ~1.4–1.6× the speed of 316 with short, breakable chips; still work-hardens, so use rigid setups, positive rake, sharp carbide and generous coolant, and avoid dwelling.
Can 316F be welded?
Not recommended for welded assemblies — the high sulfur promotes solidification hot cracking; if unavoidable, use low heat input, 316L/309 filler, minimal restraint and expect reduced joint corrosion performance.
Can 316F be formed, bent or molded?
Cold heading and severe bending are limited by the sulfide stringers; hot working 1150–1250 °C followed by solution anneal and rapid cooling is preferred, and annealed bar should be used for any forming.
Manufacturability
The process limits FabDigit applies to 316F. Every 316F part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Excellent72 / 100 |
|---|---|
| ISO material group | M.1 |
| Cutting speed (rough / finish) | 150 / 180 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
316F chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | ≤ 0.08 | 0.06 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 1 | 0.6 |
| Praised P permitted to aid machinability | ≤ 0.2 | 0.05 |
| Sintentional sulfur for free machining | ≥ 0.1 | 0.18 |
| Cr | 16 – 18 | 17 |
| Ni | 10 – 14 | 12 |
| Mo | 1.75 – 2.5 | 2.1 |
| Fe | balance |
What surface finishes work on 316F?
Passivate per ASTM A967 (nitric or citric) after machining, expecting less uniform passivity than 316; electropolishing and mirror polishing are compromised by inclusion pull-out, and plating requires careful activation.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 316F in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S31620
How much does 316F cost?
316F is a standard-cost stainless steel ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
316F — frequently asked
What is 316F used for?
316F is typically used for marine machined fittings, surgical hardware, screw-machine valve components, pump and instrument shafts, threaded fasteners and inserts and hydraulic fittings and adapters. In short: free-machining marine stainless.
What is the yield strength of 316F?
316F has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 70% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 316F easy to machine?
Yes — machinability is rated very good (72/100, better than 99% of stainless steel grades). Runs well on multi-spindle and CNC lathes at ~1.4–1.6× the speed of 316 with short, breakable chips; still work-hardens, so use rigid setups, positive rake, sharp carbide and generous coolant, and avoid dwelling.
Can 316F be welded?
Not readily — weldability is rated poor (25/100). Not recommended for welded assemblies — the high sulfur promotes solidification hot cracking; if unavoidable, use low heat input, 316L/309 filler, minimal restraint and expect reduced joint corrosion performance.
What surface finishes work on 316F?
Passivate per ASTM A967 (nitric or citric) after machining, expecting less uniform passivity than 316; electropolishing and mirror polishing are compromised by inclusion pull-out, and plating requires careful activation.
Can 316F be formed, bent or molded?
Cold heading and severe bending are limited by the sulfide stringers; hot working 1150–1250 °C followed by solution anneal and rapid cooling is preferred, and annealed bar should be used for any forming.
What is the maximum service temperature of 316F?
316F is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 316F cost?
316F is a standard-cost stainless steel ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 316F?
Yes — 316F is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A582/A582M — Free-Machining Stainless Steel Bars — ASTM International (2021)
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- UNS S31620 alloy designation data (SAE/ASTM Metals & Alloys in the Unified Numbering System) — SAE International / ASTM (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.