Stainless Steel 1.3955-ST (Solution annealed)
Heat-treated state · default condition
EN 1.3955
Standard supply condition for all corrosion-service castings; dissolves carbides and restores maximum corrosion resistance and ductility.
Values for the ST condition
Other 1.3955 tempers and conditions
1.3955 is listed in 5 conditions; see the grade overview at 1.3955.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Cheapest condition for non-corrosive structural or ornamental castings only; retained carbides make it sensitization-prone. | 250 | 500 | 30 | 155 HB | 2.3 % IACS |
STDefaultThis page Solution annealed | Standard supply condition for all corrosion-service castings; dissolves carbides and restores maximum corrosion resistance and ductility. | 255 | 520 | 50 | 140 HB | — |
Solution annealed after hot isostatic pressing | Choose for pressure-tight, radiographically clean castings (valve/pump bodies, nuclear and subsea parts) where micro-shrinkage must be closed. | 265 | 545 | 55 | 145 HB | 2.3 % IACS |
Centrifugally cast + solution annealed (ASTM A451 CPF8 type) | Pipe and cylinder forms with denser, finer structure and higher strength than static castings. | 275 | 545 | 45 | 150 HB | 2.3 % IACS |
CF8A-type | Same chemistry but ferrite balanced to a higher level for greater strength where a stronger casting is specified. | 285 | 570 | 45 | 155 HB | 2.4 % IACS |
What is 1.3955-ST?
1.3955-ST is 1.3955 heat treated to ST — standard supply condition for all corrosion-service castings; dissolves carbides and restores maximum corrosion resistance and ductility. 1.3955-ST has a yield strength of 255 MPa (37 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 193 GPa (28 Msi). 1.3955-ST 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
- Ductile — tolerates forming and impact — 50%, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
Limitations
- Low strength — 255 MPa (37 ksi), worse than 87% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- Limited formability — 25/100, worse than 78% of stainless steel grades
1.3955-ST properties
Typical room-temperature values for 1.3955-ST; 12 are specific to this condition. Other listed values are 1.3955 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.3955-ST 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
1.3955-ST has a yield strength of 255 MPa (37 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
1.3955-ST 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
1.3955-ST conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.3955-ST takes about 58 MJ of energy and emits 4.2 kg of CO₂ — more than 66% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
1.3955-ST's machinability is fair (40/100, better than 72% of stainless steel grades); weldability very good (75/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.3955-ST
Is 1.3955 easy to machine?
Gummy and work-hardening: use sharp positive-rake carbide, heavy positive feed to cut under the hardened skin, ~60–110 m/min, flood coolant; avoid dwelling.
Can 1.3955 be welded?
Readily welded with ER308/E308 (or 308L for as-welded corrosion service) by GTAW/SMAW; no preheat, keep interpass below ~150 °C and post-weld solution anneal for critical corrosion duty.
Can 1.3955 be formed, bent or molded?
Sand, investment and centrifugal casting all suitable; good fluidity with ~2.0–2.5 % solidification shrinkage — feed heavy sections generously and control ferrite (FN 5–15) to avoid hot tearing.
What surface finishes work on 1.3955?
Pickle and passivate (ASTM A967) or shot blast + electropolish; cannot be anodized, and casting skin porosity limits mirror polishing.
1.3955 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 A743 CF8 limit; EN GX12CrNi18-11 allows up to ~0.15 C | ≤ 0.08 | 0.06 |
| Mn | ≤ 1.5 | 0.8 |
| Sihigh Si aids fluidity | ≤ 2 | 1.2 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 18 – 21 | 19.5 |
| Ni | 8 – 11 | 9.5 |
| Moresidual only | ≤ 0.5 | 0.2 |
| Fe | balance | — |
1.3955-ST — frequently asked
What is 1.3955-ST used for?
1.3955-ST is typically used for valve bodies, pump casings and process piping fittings. In short: general-purpose cast 304; service to 760 °C; widely available casting grade.
What is the yield strength of 1.3955-ST?
1.3955-ST has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 1.3955-ST easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Gummy and work-hardening: use sharp positive-rake carbide, heavy positive feed to cut under the hardened skin, ~60–110 m/min, flood coolant; avoid dwelling.
Can 1.3955-ST be welded?
Yes — weldability is rated very good (75/100). Readily welded with ER308/E308 (or 308L for as-welded corrosion service) by GTAW/SMAW; no preheat, keep interpass below ~150 °C and post-weld solution anneal for critical corrosion duty.
What surface finishes work on 1.3955-ST?
Pickle and passivate (ASTM A967) or shot blast + electropolish; cannot be anodized, and casting skin porosity limits mirror polishing.
Can 1.3955-ST be formed, bent or molded?
Sand, investment and centrifugal casting all suitable; good fluidity with ~2.0–2.5 % solidification shrinkage — feed heavy sections generously and control ferrite (FN 5–15) to avoid hot tearing.
What is the maximum service temperature of 1.3955-ST?
1.3955-ST 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.
What is the difference between 1.3955-ST and 1.3955-CF8A?
ST is the default condition — standard supply condition for all corrosion-service castings; dissolves carbides and restores maximum corrosion resistance and ductility. CF8A: same chemistry but ferrite balanced to a higher level for greater strength where a stronger casting is specified. Yield strength is 255 MPa in ST versus 285 MPa in CF8A.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application (grade CF8) — ASTM International (2019)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts (CF8, CF8A) — ASTM International (2018)
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
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.