Stainless Steel 1.4305 +AT (Solution annealed)
Heat-treated state · default condition
EN 1.4305 · UNS S30300 · AISI/SAE 303 · JIS SUS303 · GB Y1Cr18Ni9
Standard stock condition for hot-rolled/peeled and centreless-ground bar; maximum corrosion resistance and ductility, softest chips.
Values for the +AT condition
Other 1.4305 tempers and conditions
1.4305 is listed in 5 conditions; see the grade overview at 1.4305.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ATDefaultThis page Solution annealed | Standard stock condition for hot-rolled/peeled and centreless-ground bar; maximum corrosion resistance and ductility, softest chips. | 260 | 620 | 48 | 160 HB | — |
+AT, peeled / centreless-ground bright bar | Annealed bar turned/ground to close diameter tolerance — pick when the outside diameter is used as-supplied on CNC parts. | 265 | 620 | 45 | 165 HB | 2.4 % IACS |
Cold drawn, Rm ≥ 700 MPa | Light cold-drawn bar: the usual automatic-lathe stock — straight, bright, better chip control and higher strength than +AT. | 520 | 760 | 25 | 230 HB | — |
Cold drawn, Rm ≥ 800 MPa | Harder cold-drawn bar for shafts, pins and fasteners needing higher proof strength and the cleanest possible turned finish. | 640 | 860 | 16 | 26 HRC | — |
Cold drawn, Rm ≥ 900 MPa | Heavily drawn small-diameter bar/wire where maximum strength and stiffness of the blank matter more than ductility. | 740 | 960 | 10 | 30 HRC | — |
What is 1.4305 +AT?
1.4305 +AT is 1.4305 heat treated to +AT — standard stock condition for hot-rolled/peeled and centreless-ground bar; maximum corrosion resistance and ductility, softest chips. 1.4305 +AT 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 48% and the elastic modulus is 193 GPa (28 Msi). 1.4305 +AT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- Easy to machine — 58/100, better than 97% of stainless steel grades
- Ductile — tolerates forming and impact — 48%, better than 85% of stainless steel grades
Limitations
- Hard to polish — 45/100, worse than 96% of stainless steel grades
- Difficult to weld — 22/100, worse than 94% of stainless steel grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
1.4305 +AT properties
Typical room-temperature values for 1.4305 +AT; 17 are specific to this condition. Other listed values are 1.4305 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4305 +AT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
1.4305 +AT 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 48% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
1.4305 +AT is rated for continuous service to 700°C (1,292 °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 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
1.4305 +AT 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 1.4305 +AT takes about 54 MJ of energy and emits 4.5 kg of CO₂ — less than 59% of stainless steel grades. Typical recycled content is 70%.
Manufacturability7
1.4305 +AT's machinability is good (58/100, better than 97% of stainless steel grades); weldability poor (22/100); formability fair (42/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4305 +AT
Is 1.4305 easy to machine?
The benchmark free-machining stainless: run 60–100 m/min HSS or 150–250 m/min carbide with sharp positive-rake tools, good chip flow and generous coolant; expect ~1.5–2× the material removal rate of 304 with far better tool life.
Can 1.4305 be welded?
Not recommended — 0.15–0.35 % S promotes solidification (hot) cracking; if unavoidable, use 308L/309L filler, low heat input, no filler-free autogenous welds, and accept reduced corrosion resistance.
Can 1.4305 be formed, bent or molded?
Limited cold formability: gentle bends with large radii only, avoid heavy heading, thread rolling or deep drawing; hot work 1150–1250 °C then solution anneal 1010–1120 °C and water quench.
What surface finishes work on 1.4305?
Passivate per ASTM A967 (citric or nitric) after machining to remove smeared sulphides; electroplating and PVD work with proper activation, but mirror polishing and electropolishing reveal sulphide pits — use 304/316 if cosmetic finish is critical.
1.4305 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 |
|---|---|---|
| CEN 10088-3 max | ≤ 0.1 | 0.06 |
| Si | ≤ 1 | 0.5 |
| Mncombines with S as MnS chip breakers | ≤ 2 | 1.3 |
| P | ≤ 0.05 | 0.03 |
| Sintentional free-machining addition | 0.15 – 0.35 | 0.25 |
| Cr | 17 – 19 | 18 |
| Ni | 8 – 10 | 9 |
| Cu | ≤ 1 | 0.4 |
| Mooptional/residual (AISI 303 allows ≤0.60 %) | ≤ 0.6 | — |
| Nresidual limit per EN 10088-3 | ≤ 0.11 | 0.04 |
| Fe | balance | — |
1.4305 +AT — frequently asked
What is 1.4305 +AT used for?
1.4305 +AT is typically used for precision turned fittings, fasteners and valve components. In short: best-machining austenitic stainless; not recommended for welding; turning-optimised 304 variant.
What is the yield strength of 1.4305 +AT?
1.4305 +AT 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 1.4305 +AT easy to machine?
Reasonably — machinability is rated good (58/100, better than 97% of stainless steel grades). The benchmark free-machining stainless: run 60–100 m/min HSS or 150–250 m/min carbide with sharp positive-rake tools, good chip flow and generous coolant; expect ~1.5–2× the material removal rate of 304 with far better tool life.
Can 1.4305 +AT be welded?
Not readily — weldability is rated poor (22/100). Not recommended — 0.15–0.35 % S promotes solidification (hot) cracking; if unavoidable, use 308L/309L filler, low heat input, no filler-free autogenous welds, and accept reduced corrosion resistance.
What surface finishes work on 1.4305 +AT?
Passivate per ASTM A967 (citric or nitric) after machining to remove smeared sulphides; electroplating and PVD work with proper activation, but mirror polishing and electropolishing reveal sulphide pits — use 304/316 if cosmetic finish is critical.
Can 1.4305 +AT be formed, bent or molded?
Limited cold formability: gentle bends with large radii only, avoid heavy heading, thread rolling or deep drawing; hot work 1150–1250 °C then solution anneal 1010–1120 °C and water quench.
What is the maximum service temperature of 1.4305 +AT?
1.4305 +AT 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.
Sources
- EN 10088-3 Stainless steels — Technical delivery conditions for semi-finished products, bars, rods, wire, sections — CEN (2014)
- ASTM A582/A582M Free-Machining Stainless Steel Bars — ASTM (2021)
- GB/T 1220 — SAC (2007)
- JIS G 4303 Stainless steel bars (SUS303) — JSA (2012)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Outokumpu / Sandvik free-machining austenitic bar datasheets (4305 / 303) — Outokumpu; Sandvik (2023)
- (SMM) / Mysteel — SMM; Mysteel (2026)
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.