Stainless Steel 1.4570 +AT (Solution annealed)
Heat-treated state · default condition
EN 1.4570
Softest and most corrosion-resistant condition; pick for large-diameter bar, subsequent cold forming, or when maximum ductility is needed.
Values for the +AT condition
Other 1.4570 tempers and conditions
1.4570 is listed in 7 conditions; see the grade overview at 1.4570.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ATDefaultThis page Solution annealed | Softest and most corrosion-resistant condition; pick for large-diameter bar, subsequent cold forming, or when maximum ductility is needed. | 260 | 600 | 45 | 175 HB | — |
Annealed then bright cold drawn | Default stock condition for automatic-lathe bar: good size tolerance, straightness and chip control with a modest strength increase. | 500 | 700 | 18 | 220 HB | — |
Cold worked to tensile class Rm ≥ 700 MPa | Lightest EN 10088-3 cold-worked strength class; use for larger diameters where only a small strength uplift is required. | 520 | 760 | 20 | 20 HRC | 2.4 % IACS |
+CG / h6 | Choose when close diameter tolerance (h6/h7) and a smooth turned-free surface are needed for shafts running in bushings. | 520 | 720 | 16 | 19 HRC | 2.4 % IACS |
Cold worked to tensile class Rm ≥ 800 MPa | Most common cold-worked strength class for small/medium free-machining bar in screw-machine work. | 620 | 860 | 13 | 25 HRC | 2.4 % IACS |
Cold worked to tensile class Rm ≥ 900 MPa | Higher-strength drawn bar for small-diameter shafts and pins that must resist bending without heat treatment. | 720 | 960 | 9 | 30 HRC | 2.4 % IACS |
Cold worked to tensile class Rm ≥ 1000 MPa | Maximum standard cold-drawn strength, limited to small diameters; ductility and impact toughness are low. | 820 | 1,060 | 7 | 33 HRC | 2.4 % IACS |
What is 1.4570 +AT?
1.4570 +AT is 1.4570 heat treated to +AT — softest and most corrosion-resistant condition; pick for large-diameter bar, subsequent cold forming, or when maximum ductility is needed. 1.4570 +AT has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi). 1.4570 +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 — 72/100, better than 99% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Hard to polish — 40/100, worse than 99% of stainless steel grades
- Difficult to weld — 20/100, worse than 95% of stainless steel grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
1.4570 +AT properties
Typical room-temperature values for 1.4570 +AT; 12 are specific to this condition. Other listed values are 1.4570 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4570 +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).
Mechanical16
1.4570 +AT has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
1.4570 +AT is rated for continuous service to 760°C (1,400 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
1.4570 +AT conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4570 +AT takes about 53 MJ of energy and emits 5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
1.4570 +AT's machinability is very good (72/100, better than 99% of stainless steel grades); weldability poor (20/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4570 +AT
Is 1.4570 easy to machine?
Best-machining austenitic stainless: run ~30–50 % higher speeds than 304, use sharp positive-rake carbide, high-pressure flood coolant and avoid dwelling to prevent work-hardened glazing.
Can 1.4570 be welded?
Not recommended — 0.15–0.35 % S causes hot (solidification) cracking; if unavoidable use 312 or 309 filler, minimal heat input and no restraint.
Can 1.4570 be formed, bent or molded?
Only light bending and mild cold heading; sulfide stringers make transverse ductility poor, so bend across the rolling direction with generous radii and hot form at 1150–1200 °C.
What surface finishes work on 1.4570?
Passivate per ASTM A967 (nitric-based, note sulfide attack risk) after machining; electropolishing and mirror polishing are difficult because inclusions pull out — plating or black oxide are common alternatives.
1.4570 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 |
|---|---|---|
| CX6 designation | ≤ 0.06 | 0.05 |
| Si | ≤ 1 | 0.5 |
| Mncombines with S as MnS chip breakers | ≤ 2 | 1.5 |
| P | ≤ 0.05 | 0.03 |
| Sfree-machining addition | 0.15 – 0.35 | 0.27 |
| Cr | 17 – 19 | 18 |
| Ni | 8 – 10 | 9 |
| Culowers work hardening, improves cold heading and chip control | 1.3 – 2.5 | 1.9 |
| Moresidual, optional | ≤ 0.8 | 0.3 |
| N | ≤ 0.11 | 0.05 |
| Fe | balance | — |
1.4570 +AT — frequently asked
What is 1.4570 +AT used for?
1.4570 +AT is typically used for precision machined parts, fittings, fasteners and valve components. In short: best-machining austenitic stainless; free-machining 303 variant; not recommended for welding.
What is the yield strength of 1.4570 +AT?
1.4570 +AT has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 1.4570 +AT easy to machine?
Yes — machinability is rated very good (72/100, better than 99% of stainless steel grades). Best-machining austenitic stainless: run ~30–50 % higher speeds than 304, use sharp positive-rake carbide, high-pressure flood coolant and avoid dwelling to prevent work-hardened glazing.
Can 1.4570 +AT be welded?
Not readily — weldability is rated poor (20/100). Not recommended — 0.15–0.35 % S causes hot (solidification) cracking; if unavoidable use 312 or 309 filler, minimal heat input and no restraint.
What surface finishes work on 1.4570 +AT?
Passivate per ASTM A967 (nitric-based, note sulfide attack risk) after machining; electropolishing and mirror polishing are difficult because inclusions pull out — plating or black oxide are common alternatives.
Can 1.4570 +AT be formed, bent or molded?
Only light bending and mild cold heading; sulfide stringers make transverse ductility poor, so bend across the rolling direction with generous radii and hot form at 1150–1200 °C.
What is the maximum service temperature of 1.4570 +AT?
1.4570 +AT 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.
Sources
- EN 10088-3 Stainless steels — Semi-finished products, bars, rods, sections — CEN (2014)
- EN 10088-1 Stainless steels — List of stainless steels (physical properties) — CEN (2014)
- ASTM A582/A582M Free-Machining Stainless Steel Bars — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.16 — Machining (machinability ratings) — ASM International (1989)
- Free-machining austenitic bar datasheets (Outokumpu, Sandvik, Ugitech) — various producers (2023)
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.