Stainless Steel S30435-ST (Solution annealed)
Heat-treated state · default condition
UNS S30435
Standard supply condition for A213/A249 superheater and reheater tubing — Cu and Nb in solution, ready for in-service precipitation strengthening.
Values for the ST condition
Other S30435 tempers and conditions
S30435 is listed in 2 conditions; see the grade overview at S30435.
- ST
- CD
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefaultThis page Solution annealed | Standard supply condition for A213/A249 superheater and reheater tubing — Cu and Nb in solution, ready for in-service precipitation strengthening. | 300 | 655 | 45 | 180 HB | 2.3 % IACS |
Cold drawn | Intermediate mill condition or special order where higher room-temperature strength and tight tolerance matter more than ductility; not the code condition for creep service. | 620 | 830 | 20 | 25 HRC | 2.3 % IACS |
What is S30435-ST?
S30435-ST is S30435 heat treated to ST — standard supply condition for A213/A249 superheater and reheater tubing — Cu and Nb in solution, ready for in-service precipitation strengthening. S30435-ST has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 197 GPa (28.6 Msi). S30435-ST 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
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Forms and bends easily — 70/100, better than 79% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
S30435-ST properties
Typical room-temperature values for S30435-ST; 23 are specific to this condition. Other listed values are S30435 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
S30435-ST 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
S30435-ST has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 197 GPa (28.6 Msi).
Thermal6
S30435-ST is rated for continuous service to 700°C (1,292 °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 16.8 µm/m·K (9.33 µin/in·°F).
Electrical3
S30435-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 S30435-ST takes about 55 MJ of energy and emits 4.6 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
S30435-ST's machinability is fair (38/100, better than 63% of stainless steel grades); weldability good (68/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S30435-ST
Is S30435 easy to machine?
Gummy, strongly work-hardening austenitic: rigid setup, positive-rake sharp carbide, 60–100 m/min, heavy feed and flood coolant, avoid dwelling to prevent glazing.
Can S30435 be welded?
GTAW/GMAW with low heat input, interpass < 150 °C, no post-weld heat treatment normally; use matching Cu-Nb 304H filler or ERNiCr-3/EPRI P87 for dissimilar joints — watch hot-cracking and creep-strength mismatch at the HAZ.
Can S30435 be formed, bent or molded?
Cold bends and expansions are readily made in the solution-annealed state; cold work above ~20% should be re-solution annealed, and hot working is done at 1100–1200 °C followed by rapid cooling.
What surface finishes work on S30435?
Pickle and passivate per ASTM A380 after welding or hot work; ID shot-blasting is the usual order option to improve steam-side oxidation resistance; not anodizable.
S30435 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 |
|---|---|---|
| CH-grade carbon level for creep strength | 0.07 – 0.13 | 0.1 |
| Si | ≤ 0.3 | 0.2 |
| Mn | ≤ 1 | 0.8 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.01 | 0 |
| Cr | 17 – 19 | 18 |
| Ni | 7.5 – 10.5 | 9 |
| Cuforms fine Cu-rich precipitates during service — main creep strengthener | 2.5 – 3.5 | 3 |
| NbMX carbonitride strengthening | 0.3 – 0.6 | 0.45 |
| N | 0.05 – 0.12 | 0.1 |
| Bgrain-boundary strengthening (when specified) | 0 – 0.01 | 0 |
| Alrestricted to keep Nb effective | ≤ 0.03 | 0.01 |
| Fe | balance | — |
S30435-ST — frequently asked
What is S30435-ST used for?
S30435-ST is typically used for boiler superheater tubes, reheater tubing and high-temperature pressure parts. In short: creep-strengthened 304H upgrade; cu-Nb precipitation hardening; mainly boiler tube product.
What is the yield strength of S30435-ST?
S30435-ST has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is S30435-ST easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Gummy, strongly work-hardening austenitic: rigid setup, positive-rake sharp carbide, 60–100 m/min, heavy feed and flood coolant, avoid dwelling to prevent glazing.
Can S30435-ST be welded?
Yes — weldability is rated good (68/100). GTAW/GMAW with low heat input, interpass < 150 °C, no post-weld heat treatment normally; use matching Cu-Nb 304H filler or ERNiCr-3/EPRI P87 for dissimilar joints — watch hot-cracking and creep-strength mismatch at the HAZ.
What surface finishes work on S30435-ST?
Pickle and passivate per ASTM A380 after welding or hot work; ID shot-blasting is the usual order option to improve steam-side oxidation resistance; not anodizable.
Can S30435-ST be formed, bent or molded?
Cold bends and expansions are readily made in the solution-annealed state; cold work above ~20% should be re-solution annealed, and hot working is done at 1100–1200 °C followed by rapid cooling.
What is the maximum service temperature of S30435-ST?
S30435-ST is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S30435-ST and S30435-CD?
ST is the default condition — standard supply condition for A213/A249 superheater and reheater tubing — Cu and Nb in solution, ready for in-service precipitation strengthening. CD: intermediate mill condition or special order where higher room-temperature strength and tight tolerance matter more than ductility; not the code condition for creep service. Yield strength is 300 MPa in ST versus 620 MPa in CD.
Sources
- ASTM A213/A213M — Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes — ASTM International (2022)
- ASTM A249/A249M — Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes — ASTM International (2022)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- Super304H (18Cr-9Ni-3Cu-Nb-N) boiler tube data — Nippon Steel (Sumitomo Metals) (2019)
- 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.