Stainless Steel ZG0Cr18Ni9-ST (Solution annealed)
Heat-treated state · default condition
ASTM CF3
Standard supplied condition for all pressure-containing castings; maximum corrosion resistance and ductility.
Values for the ST condition
Other ZG0Cr18Ni9 tempers and conditions
ZG0Cr18Ni9 is listed in 4 conditions; see the grade overview at ZG0Cr18Ni9.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefaultThis page Solution annealed | Standard supplied condition for all pressure-containing castings; maximum corrosion resistance and ductility. | 245 | 525 | 55 | 140 HB | — |
As fabricated | Only for non-pressure, non-corrosive decorative or structural parts; carbides and casting stresses remain, corrosion resistance is degraded. | 250 | 490 | 35 | 150 HB | 2.4 % IACS |
As-welded deposit | The reason this ultra-low-carbon grade exists: casting repaired or welded into an assembly and put into service without re-solutioning. | 250 | 510 | 45 | 150 HB | 2.4 % IACS |
hot isostatically pressed then solution treated | Choose for fatigue- or leak-critical castings (pump/valve bodies, subsea parts) where internal microporosity must be closed. | 255 | 545 | 60 | 145 HB | 2.4 % IACS |
What is ZG0Cr18Ni9-ST?
ZG0Cr18Ni9-ST is ZG0Cr18Ni9 heat treated to ST — standard supplied condition for all pressure-containing castings; maximum corrosion resistance and ductility. ZG0Cr18Ni9-ST has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 525 MPa (76.1 ksi) — weaker than 94% of stainless steel grades. Elongation at break is 55% and the elastic modulus is 193 GPa (28 Msi). ZG0Cr18Ni9-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
- Readily welded — 92/100, better than 98% of stainless steel grades
- Ductile — tolerates forming and impact — 55%, better than 97% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
Limitations
- Low strength — 245 MPa (35.5 ksi), worse than 94% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
ZG0Cr18Ni9-ST properties
Typical room-temperature values for ZG0Cr18Ni9-ST; 12 are specific to this condition. Other listed values are ZG0Cr18Ni9 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
ZG0Cr18Ni9-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
ZG0Cr18Ni9-ST has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 525 MPa (76.1 ksi) — weaker than 94% of stainless steel grades. Elongation at break is 55% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
ZG0Cr18Ni9-ST is rated for continuous service to 425°C (797 °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 µm/m·K (9.44 µin/in·°F).
Electrical3
ZG0Cr18Ni9-ST conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 68% of stainless steel grades.
Sustainability4
Producing a kilogram of ZG0Cr18Ni9-ST takes about 55 MJ of energy and emits 5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
ZG0Cr18Ni9-ST's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (92/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZG0Cr18Ni9-ST
Is ZG0Cr18Ni9 easy to machine?
Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, heavy positive feed (no dwelling), 60–120 m/min, flood coolant; cast skin/sand inclusions dull the first cut.
Can ZG0Cr18Ni9 be welded?
Excellent — GTAW/SMAW with ER308L/E308L filler, no preheat, low interpass (<150 °C); the ≤0.03 % C plus 5–20 FN ferrite lets repairs stay in service without post-weld solution annealing.
Can ZG0Cr18Ni9 be formed, bent or molded?
Wide freezing range needs generous risers, chills on heavy sections and a solidification simulation; keep ferrite 8–18 FN to avoid hot cracking while staying below sigma-formation risk.
What surface finishes work on ZG0Cr18Ni9?
Passivate (nitric or citric per ASTM A967) after machining; shot blast + pickling to remove scale; electropolishable for sanitary service, but porosity limits true mirror polish.
ZG0Cr18Ni9 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 |
|---|---|---|
| Cultra-low carbon for sensitization resistance | ≤ 0.03 | 0.02 |
| Si | ≤ 2 | 1.2 |
| Mn | ≤ 1.5 | 1 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 17 – 21 | 19 |
| Ni | 8 – 12 | 9.5 |
| Moresidual only | ≤ 0.5 | 0.2 |
| Fe | balance | — |
ZG0Cr18Ni9-ST — frequently asked
What is ZG0Cr18Ni9-ST used for?
ZG0Cr18Ni9-ST is typically used for welded valve castings, pump housings and food and pharmaceutical process castings. In short: low-carbon cast austenitic; best as-welded corrosion resistance; CF3 equivalent.
What is the yield strength of ZG0Cr18Ni9-ST?
ZG0Cr18Ni9-ST has a typical yield strength of 245 MPa (35.5 ksi) and a tensile strength of 525 MPa (76.1 ksi) — weaker than 94% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is ZG0Cr18Ni9-ST easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, heavy positive feed (no dwelling), 60–120 m/min, flood coolant; cast skin/sand inclusions dull the first cut.
Can ZG0Cr18Ni9-ST be welded?
Yes — weldability is rated excellent (92/100). Excellent — GTAW/SMAW with ER308L/E308L filler, no preheat, low interpass (<150 °C); the ≤0.03 % C plus 5–20 FN ferrite lets repairs stay in service without post-weld solution annealing.
What surface finishes work on ZG0Cr18Ni9-ST?
Passivate (nitric or citric per ASTM A967) after machining; shot blast + pickling to remove scale; electropolishable for sanitary service, but porosity limits true mirror polish.
Can ZG0Cr18Ni9-ST be formed, bent or molded?
Wide freezing range needs generous risers, chills on heavy sections and a solidification simulation; keep ferrite 8–18 FN to avoid hot cracking while staying below sigma-formation risk.
What is the maximum service temperature of ZG0Cr18Ni9-ST?
ZG0Cr18Ni9-ST is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZG0Cr18Ni9-ST and ZG0Cr18Ni9-F?
ST is the default condition — standard supplied condition for all pressure-containing castings; maximum corrosion resistance and ductility. F: only for non-pressure, non-corrosive decorative or structural parts; carbides and casting stresses remain, corrosion resistance is degraded. Yield strength is 245 MPa in ST versus 250 MPa in F.
Sources
- ASTM A351/A351M Castings, Austenitic, for Pressure-Containing Parts (CF3) — ASTM International (2022)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
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.