Stainless Steel 1.4594 +AT (Solution annealed)
Heat-treated state · default condition
EN 1.4594
Mill delivery and stocking condition: machine or cold-form here, then age to the required strength level.
Values for the +AT condition
Other 1.4594 tempers and conditions
1.4594 is listed in 7 conditions; see the grade overview at 1.4594.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Precipitation hardened, Rm ≥ 930 MPa | Lowest-strength / highest-toughness aged condition — choose for shafts and fittings needing good impact and SCC resistance. | 760 | 970 | 18 | 28 HRC | — |
+ATDefaultThis page Solution annealed | Mill delivery and stocking condition: machine or cold-form here, then age to the required strength level. | 795 | 965 | 14 | 27 HRC | — |
Precipitation hardened, Rm ≥ 1000 MPa | Balanced strength/toughness aged condition for valve stems, pump shafts and structural fasteners. | 880 | 1,030 | 16 | 32 HRC | — |
Solution annealed + cold drawn bar/wire | Cold-drawn precision bar and wire supplied in the annealed-then-drawn state for close tolerance and higher as-supplied strength before aging. | 900 | 1,050 | 10 | 31 HRC | 2.2 % IACS |
Precipitation hardened, Rm ≥ 1070 MPa | Highest standard EN strength level — for highly loaded shafts, springs and aerospace/oil-field components where some toughness is traded for strength. | 1,010 | 1,100 | 15 | 34 HRC | — |
Aged 538 °C / 4 h | US-spec aging step above the EN levels; use where ~1200 MPa strength with moderate ductility is specified. | 1,140 | 1,210 | 14 | 37 HRC | — |
Aged 482 °C (900 °F) for 1 h, peak hardness | Peak-hardness condition for maximum strength and wear resistance; lowest toughness and SCC margin of the aged states. | 1,240 | 1,310 | 13 | 41 HRC | — |
What is 1.4594 +AT?
1.4594 +AT is 1.4594 heat treated to +AT — mill delivery and stocking condition: machine or cold-form here, then age to the required strength level. 1.4594 +AT has a yield strength of 795 MPa (115 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 96% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 200 GPa (29 Msi). 1.4594 +AT has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- High strength — 795 MPa (115 ksi), better than 96% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- Easy to machine — 45/100, better than 84% of stainless steel grades
Limitations
- Limited ductility — 14%, worse than 91% of stainless steel grades
- Limited service temperature — 350°C (662 °F), worse than 84% of stainless steel grades
1.4594 +AT properties
Typical room-temperature values for 1.4594 +AT; 16 are specific to this condition. Other listed values are 1.4594 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4594 +AT has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
1.4594 +AT has a yield strength of 795 MPa (115 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 96% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4594 +AT is rated for continuous service to 350°C (662 °F). It conducts heat at 17 W/m·K (9.82 BTU/hr·ft·°F), better than 71% of stainless steel grades. Thermal expansion is 10.6 µm/m·K (5.89 µin/in·°F).
Electrical3
1.4594 +AT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4594 +AT takes about 55 MJ of energy and emits 4 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability6
1.4594 +AT's machinability is fair (45/100, better than 84% of stainless steel grades); weldability very good (70/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4594 +AT
Is 1.4594 easy to machine?
Machine in +AT (≈27 HRC): rigid setups, sharp positive-rake carbide, 60–100 m/min, heavy feed to cut under the work-hardened skin; aged parts above 34 HRC need reduced speeds or ceramic/CBN finishing.
Can 1.4594 be welded?
Good GTAW/GMAW/EB weldability with matching or AWS ER630 filler, no preheat needed; re-solution-anneal + age for full joint strength, or age-only for partial recovery.
Can 1.4594 be formed, bent or molded?
Cold form and bend only in the solution-annealed condition with generous radii; hot work 1150–950 °C then solution anneal ~1040 °C and quench.
What surface finishes work on 1.4594?
Takes a fine mirror polish and passivates readily per ASTM A967 (nitric or citric); no anodizing — chrome/nickel plating requires low-hydrogen practice plus 190 °C bake for aged high-strength conditions.
1.4594 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 |
|---|---|---|
| Clow carbon for toughness | ≤ 0.05 | 0.03 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 14 – 16 | 15 |
| Ni | 5 – 7 | 6 |
| Moimproves pitting resistance vs 17-4PH | 0.5 – 1 | 0.75 |
| Cuepsilon-Cu precipitation hardener | 1.25 – 1.75 | 1.5 |
| Nb8 × C minimum (Nb+Ta) | 0.24 – 0.6 | 0.35 |
| Fe | balance | — |
1.4594 +AT — frequently asked
What is 1.4594 +AT used for?
1.4594 +AT is typically used for shafts, valve stems, paper machinery rolls and marine hardware. In short: tougher than 17-4PH; better corrosion PH stainless; custom 450 chemistry.
What is the yield strength of 1.4594 +AT?
1.4594 +AT has a typical yield strength of 795 MPa (115 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 96% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 1.4594 +AT easy to machine?
Reasonably — machinability is rated fair (45/100, better than 84% of stainless steel grades). Machine in +AT (≈27 HRC): rigid setups, sharp positive-rake carbide, 60–100 m/min, heavy feed to cut under the work-hardened skin; aged parts above 34 HRC need reduced speeds or ceramic/CBN finishing.
Can 1.4594 +AT be welded?
Yes — weldability is rated very good (70/100). Good GTAW/GMAW/EB weldability with matching or AWS ER630 filler, no preheat needed; re-solution-anneal + age for full joint strength, or age-only for partial recovery.
What surface finishes work on 1.4594 +AT?
Takes a fine mirror polish and passivates readily per ASTM A967 (nitric or citric); no anodizing — chrome/nickel plating requires low-hydrogen practice plus 190 °C bake for aged high-strength conditions.
Can 1.4594 +AT be formed, bent or molded?
Cold form and bend only in the solution-annealed condition with generous radii; hot work 1150–950 °C then solution anneal ~1040 °C and quench.
What is the maximum service temperature of 1.4594 +AT?
1.4594 +AT is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4594 +AT and 1.4594-H900?
+AT is the default condition — mill delivery and stocking condition: machine or cold-form here, then age to the required strength level. H900: peak-hardness condition for maximum strength and wear resistance; lowest toughness and SCC margin of the aged states. Yield strength is 795 MPa in +AT versus 1,240 MPa in H900.
Sources
- EN 10088-3 Stainless steels – Part 3: semi-finished products, bars, rods, sections — CEN (2014)
- ASTM A564/A564M – Hot-Rolled and Cold-Finished Age-Hardening Stainless Bars (Type XM-25) — ASTM International (2019)
- Custom 450 Stainless (UNS S45000) alloy datasheet — Carpenter Technology (2020)
- ASM Handbook Vol.1 – Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 – Fatigue and Fracture — ASM International (1996)
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.