Stainless Steel 1.4458-ST (Solution annealed)
Heat-treated state · default condition
EN 1.4458
Standard delivery condition for all pressure and chemical-service castings; maximum corrosion resistance and ductility.
Values for the ST condition
Other 1.4458 tempers and conditions
1.4458 is listed in 4 conditions; see the grade overview at 1.4458.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefaultThis page Solution annealed | Standard delivery condition for all pressure and chemical-service castings; maximum corrosion resistance and ductility. | 235 | 490 | 42 | 140 HB | 1.6 % IACS |
Hot isostatically pressed then solution annealed | Specified for leak-tight, radiographed valve and pump castings where microporosity must be closed; toughness and fatigue improve. | 240 | 505 | 48 | 140 HB | 1.6 % IACS |
Spheroidize annealed | Only for non-critical, non-corrosive or rough-machining parts — interdendritic carbides/segregation cut corrosion resistance and toughness. | 250 | 470 | 28 | 150 HB | 1.6 % IACS |
Centrifugally cast tube/ring, solution annealed | Pick for pump sleeves, bushings and pipe spools: denser, finer structure than static castings gives slightly higher strength. | 255 | 520 | 40 | 145 HB | 1.6 % IACS |
What is 1.4458-ST?
1.4458-ST is 1.4458 heat treated to ST — standard delivery condition for all pressure and chemical-service castings; maximum corrosion resistance and ductility. 1.4458-ST has a yield strength of 235 MPa (34.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 98% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 193 GPa (28 Msi). 1.4458-ST has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Advantages
- Good corrosion resistance — 79/100, better than 86% of stainless steel grades
Limitations
- Low electrical conductivity — 1.6 % IACS, worse than 99% of stainless steel grades
- Low strength — 235 MPa (34.1 ksi), worse than 98% of stainless steel grades
- Poor heat conductor — 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 88% of stainless steel grades
- High embodied carbon — 5.8 kg CO₂/kg, worse than 86% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
1.4458-ST properties
Typical room-temperature values for 1.4458-ST; 23 are specific to this condition. Other listed values are 1.4458 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4458-ST has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
1.4458-ST has a yield strength of 235 MPa (34.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 98% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 193 GPa (28 Msi).
Thermal5
1.4458-ST is rated for continuous service to 500°C (932 °F). It conducts heat at 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 88% of stainless steel grades. Thermal expansion is 14.8 µm/m·K (8.22 µin/in·°F).
Electrical3
1.4458-ST conducts electricity at 1.6 % IACS, worse than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (79/100), better than 86% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4458-ST takes about 75 MJ of energy and emits 5.8 kg of CO₂ — more than 84% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
1.4458-ST's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability good (65/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4458-ST
Is 1.4458 easy to machine?
Gummy and rapidly work-hardening — rigid setup, positive-rake carbide, heavy constant feed, low speed (≈30–60 m/min) and copious coolant; avoid dwelling to prevent glazing.
Can 1.4458 be welded?
Readily welded by GTAW/SMAW with matching Nb-stabilized Alloy 20 filler (ER320LR / E320LR); use low heat input, stringer beads, interpass <150 °C, then re-solution anneal for the most aggressive acid service.
Can 1.4458 be formed, bent or molded?
Sand or investment cast with generous risering (wide freezing range, ~2.2 % shrink); no cold forming route — machine or weld-fabricate instead.
What surface finishes work on 1.4458?
Grit blast, pickle in HNO₃–HF then passivate in nitric acid for full corrosion performance; not anodizable, electropolishing gives the best surface for acid service.
1.4458 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 |
|---|---|---|
| CASTM A744 CN7M ≤0.07; EN 1.4458 (GX2NiCrMo28-20-2) ≤0.03 | ≤ 0.07 | 0.03 |
| SiEN grade ≤1.0 | ≤ 1.5 | 0.8 |
| MnA744 CN7M ≤1.50 | ≤ 2 | 1 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 19 – 22 | 20.5 |
| NiA744 CN7M 27.5–30.5; EN 26–30 | 26 – 30.5 | 28.5 |
| MoEN grade 2.0–2.5 | 2 – 3 | 2.4 |
| CuA744 CN7M 3.0–4.0; EN 1.4458 lower Cu | 1.5 – 4 | 3 |
| Febalance, ≈43–47 % | balance | — |
1.4458-ST — frequently asked
What is 1.4458-ST used for?
1.4458-ST is typically used for sulfuric acid pumps and valves, chemical processing castings and fertilizer plant equipment. In short: cast Alloy 20 equivalent; strong sulfuric acid resistance; very ductile cast stainless.
What is the yield strength of 1.4458-ST?
1.4458-ST has a typical yield strength of 235 MPa (34.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 98% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4458-ST easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Gummy and rapidly work-hardening — rigid setup, positive-rake carbide, heavy constant feed, low speed (≈30–60 m/min) and copious coolant; avoid dwelling to prevent glazing.
Can 1.4458-ST be welded?
Yes — weldability is rated good (65/100). Readily welded by GTAW/SMAW with matching Nb-stabilized Alloy 20 filler (ER320LR / E320LR); use low heat input, stringer beads, interpass <150 °C, then re-solution anneal for the most aggressive acid service.
What surface finishes work on 1.4458-ST?
Grit blast, pickle in HNO₃–HF then passivate in nitric acid for full corrosion performance; not anodizable, electropolishing gives the best surface for acid service.
Can 1.4458-ST be formed, bent or molded?
Sand or investment cast with generous risering (wide freezing range, ~2.2 % shrink); no cold forming route — machine or weld-fabricate instead.
What is the maximum service temperature of 1.4458-ST?
1.4458-ST is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4458-ST and 1.4458 ST-CF?
ST is the default condition — standard delivery condition for all pressure and chemical-service castings; maximum corrosion resistance and ductility. ST-CF: pick for pump sleeves, bushings and pipe spools: denser, finer structure than static castings gives slightly higher strength. Yield strength is 235 MPa in ST versus 255 MPa in ST-CF.
Sources
- ASTM A744/A744M — Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Severe Service (CN7M) — ASTM (2019)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM (2020)
- EN 10283 — Corrosion resistant steel castings (GX2NiCrMo28-20-2, 1.4458) — CEN (2010)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels; Cast Corrosion-Resistant Alloys — ASM International (1990)
- Alloy 20 (N08020/N08007) physical and corrosion data — Carpenter / Rolled Alloys (2021)
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.