Stainless Steel 303 · temper
Stainless Steel 303 Annealed
Properties of the Annealed condition, compared with the other 303 tempers.
Softest, most ductile and most corrosion-resistant condition; choose for cold heading, bending or when maximum ductility is needed.
What is 303 Annealed?
303 Annealed is 303 in the Annealed temper — softest, most ductile and most corrosion-resistant condition; choose for cold heading, bending or when maximum ductility is needed. 303 Annealed has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 193 GPa (28 Msi). 303 Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,400°C (2,552 °F). Cold Drawn is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Easy to machine — 66/100, better than 98% of stainless steel grades
- Ductile — tolerates forming and impact — 50%, better than 90% of stainless steel grades
Limitations
- Hard to polish — 40/100, worse than 99% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
303 Annealed properties
Typical room-temperature values for 303 Annealed — 15 properties are specific to this condition; the rest are grade-level values shared by every 303 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
303 Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
303 Annealed has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
303 Annealed is rated for continuous service to 760°C (1,400 °F). It conducts heat at 16.2 W/m·K (9.36 BTU/hr·ft·°F), better than 64% of stainless steel grades. Thermal expansion is 17.3 µm/m·K (9.61 µin/in·°F).
Electrical3
303 Annealed conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of 303 Annealed takes about 53 MJ of energy and emits 5.5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
303 Annealed's machinability is good (66/100, better than 98% of stainless steel grades); weldability poor (25/100); formability good (55/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 303 tempers and conditions
303 is also supplied in 4 other conditions. The full side-by-side table is on the 303 overview.
- Cold DrawnDefaultStandard stocked condition for screw-machine bar: higher strength, tight size tolerance and the best chip control.450 MPa yield · 240 HB
- Cold Worked 1/4 HardHigher-strength small-diameter bar and wire for fasteners where extra proof strength is required.620 MPa yield · 29 HRC
- CD Ground & PolishedPick when a precise diameter and a smooth shaft surface are needed straight from stock (pins, spindles, shafts).450 MPa yield · 240 HB
- AnnealedSoftest, most ductile and most corrosion-resistant condition; choose for cold heading, bending or when maximum ductility is needed.260 MPa yield · 165 HB
Working with 303 Annealed
Is 303 easy to machine?
The best-machining austenitic stainless: run 30–50 % faster than 304 with sharp positive-rake tools, rigid setups and generous coolant; chips break cleanly thanks to MnS.
Can 303 be welded?
Not recommended — high sulfur promotes hot cracking and porosity; if unavoidable use 308L/312 filler, low heat input and no restraint, and expect reduced corrosion resistance.
Can 303 be formed, bent or molded?
Only light cold forming (thread rolling, mild bending); transverse ductility is poor and sulfide stringers open into cracks on tight bends — use 304 for deep drawing.
What surface finishes work on 303?
Passivate per ASTM A967 (nitric or citric) after machining; electropolish improves pitting resistance, but a mirror polish is hard to achieve because sulfides pull out.
303 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 | ≤ 0.15 | 0.08 |
| Mncombines with S to form free-machining MnS | ≤ 2 | 1.5 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.2 | 0.03 |
| Sdeliberate free-machining addition | 0.15 – 0.35 | 0.25 |
| Cr | 17 – 19 | 18 |
| Ni | 8 – 10 | 9 |
| Mooptional at producer's discretion (ASTM A582) | ≤ 0.6 | — |
| Fe | balance | — |
303 Annealed — frequently asked
What is 303 Annealed used for?
303 Annealed is typically used for CNC turned shafts, valve bodies and stems, nuts and threaded fittings, bushings and spacers, shaft couplings and instrument and connector bodies. In short: easiest machining stainless.
What is the yield strength of 303 Annealed?
303 Annealed has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 303 Annealed easy to machine?
Reasonably — machinability is rated good (66/100, better than 98% of stainless steel grades). The best-machining austenitic stainless: run 30–50 % faster than 304 with sharp positive-rake tools, rigid setups and generous coolant; chips break cleanly thanks to MnS.
Can 303 Annealed be welded?
Not readily — weldability is rated poor (25/100). Not recommended — high sulfur promotes hot cracking and porosity; if unavoidable use 308L/312 filler, low heat input and no restraint, and expect reduced corrosion resistance.
What surface finishes work on 303 Annealed?
Passivate per ASTM A967 (nitric or citric) after machining; electropolish improves pitting resistance, but a mirror polish is hard to achieve because sulfides pull out.
Can 303 Annealed be formed, bent or molded?
Only light cold forming (thread rolling, mild bending); transverse ductility is poor and sulfide stringers open into cracks on tight bends — use 304 for deep drawing.
What is the maximum service temperature of 303 Annealed?
303 Annealed is rated for continuous use to about 760°C (1,400 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 303 Annealed?
Yes — 303 Annealed is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A582/A582M Free-Machining Stainless Steel Bars — ASTM International (2021)
- EN 10088-3 Stainless steels — Semi-finished products, bars, rods (1.4305) — CEN (2014)
- GB/T 1220 (Y1Cr18Ni9) — SAC (2007)
- JIS G 4303 Stainless steel bars (SUS303) — JSA (2012)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- Sandvik / Outokumpu free-machining austenitic grade datasheets — Sandvik, Outokumpu (2022)
- SMM / Mysteel — SMM, Mysteel (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.