Steel WC9 N+T+PWHT
Heat-treated state
GB WC9 · ASTM A217 Grade WC9
Condition of weld-repaired or fabricated WC9 castings after the mandatory 700–760 °C PWHT; slightly softer and tougher than as-tempered.
Values for the N+T+PWHT condition
Other WC9 tempers and conditions
WC9 is listed in 4 conditions; see the grade overview at WC9.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Intermediate soft condition supplied for rough machining or weld repair; must be re-normalized/tempered before code service. | 280 | 480 | 27 | 140 HB | — |
N+T+PWHTThis page normalized, tempered and post-weld heat treated (700–760 °C) | Condition of weld-repaired or fabricated WC9 castings after the mandatory 700–760 °C PWHT; slightly softer and tougher than as-tempered. | 310 | 510 | 25 | 155 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Standard ASTM A217 delivery condition for valve bodies and pressure castings in 450–570 °C steam/hydrocarbon service. | 330 | 530 | 24 | 165 HB | — |
Quenched and tempered | Choose for heavy-section castings needing higher yield and better low-temperature toughness within the same A217 tensile band. | 400 | 575 | 22 | 185 HB | — |
What is WC9 N+T+PWHT?
WC9 N+T+PWHT is WC9 heat treated to N+T+PWHT — condition of weld-repaired or fabricated WC9 castings after the mandatory 700–760 °C PWHT; slightly softer and tougher than as-tempered. WC9 N+T+PWHT has a yield strength of 310 MPa (45 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 83% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi). WC9 N+T+PWHT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). N+T is the default condition FabDigit quotes; N+T+PWHT is available on request or by drawing note.
Advantages
- High service temperature — 570°C (1,058 °F), better than 96% of steel grades
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
- Low strength — 310 MPa (45 ksi), worse than 83% of steel grades
- Limited formability — 22/100, worse than 76% of steel grades
WC9 N+T+PWHT properties
Typical room-temperature values for WC9 N+T+PWHT; 22 are specific to this condition. Other listed values are WC9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
WC9 N+T+PWHT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
WC9 N+T+PWHT has a yield strength of 310 MPa (45 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 83% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
WC9 N+T+PWHT is rated for continuous service to 570°C (1,058 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 71% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
WC9 N+T+PWHT conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of WC9 N+T+PWHT takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 75%.
Manufacturability8
WC9 N+T+PWHT's machinability is good (55/100, better than 62% of steel grades); weldability fair (48/100); formability poor (22/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with WC9 N+T+PWHT
Is WC9 easy to machine?
Machines like normalized 4130/4140 at roughly 55 % of 1212 — use rigid setups, carbide inserts and moderate speeds; cast skin and residual sand are abrasive, so take a heavy first cut.
Can WC9 be welded?
P-No. 5A material: preheat 200–300 °C, use E9018-B3 / ER90S-B3 (2.25Cr-1Mo) consumables, maintain interpass and apply 700–760 °C PWHT to avoid hard HAZ and reheat cracking.
Can WC9 be formed, bent or molded?
Supplied as sand or investment castings; design generous fillets and directional risering, and always normalize-and-temper the casting to break up as-cast bainitic/dendritic structure.
What surface finishes work on WC9?
Shot-blast to remove scale then aluminize, phosphate or apply high-temperature silicone/aluminium paint; not anodizable and not corrosion-resistant in wet service.
WC9 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 |
|---|---|---|
| C | 0.05 – 0.18 | 0.13 |
| Mn | 0.4 – 0.7 | 0.55 |
| Si | ≤ 0.6 | 0.35 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Cr | 2 – 2.75 | 2.35 |
| Mo | 0.9 – 1.2 | 1.05 |
| Niresidual | ≤ 0.5 | — |
| Curesidual | ≤ 0.5 | — |
| Wresidual | ≤ 0.1 | — |
| Vresidual; total residuals ≤1.00 % | ≤ 0.03 | — |
| Fe | balance | — |
WC9 N+T+PWHT — frequently asked
What is WC9 N+T+PWHT used for?
WC9 N+T+PWHT is typically used for high-temperature valve bodies, steam turbine casings and refinery piping fittings. In short: cast equivalent of P22; highest-temperature WC grade; most demanding PWHT here.
What is the yield strength of WC9 N+T+PWHT?
WC9 N+T+PWHT has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 83% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is WC9 N+T+PWHT easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like normalized 4130/4140 at roughly 55 % of 1212 — use rigid setups, carbide inserts and moderate speeds; cast skin and residual sand are abrasive, so take a heavy first cut.
Can WC9 N+T+PWHT be welded?
With care — weldability is rated fair (48/100). P-No. 5A material: preheat 200–300 °C, use E9018-B3 / ER90S-B3 (2.25Cr-1Mo) consumables, maintain interpass and apply 700–760 °C PWHT to avoid hard HAZ and reheat cracking.
What surface finishes work on WC9 N+T+PWHT?
Shot-blast to remove scale then aluminize, phosphate or apply high-temperature silicone/aluminium paint; not anodizable and not corrosion-resistant in wet service.
Can WC9 N+T+PWHT be formed, bent or molded?
Supplied as sand or investment castings; design generous fillets and directional risering, and always normalize-and-temper the casting to break up as-cast bainitic/dendritic structure.
What is the maximum service temperature of WC9 N+T+PWHT?
WC9 N+T+PWHT is rated for continuous use to about 570°C (1,058 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between WC9 N+T and WC9-ANN?
N+T is the default condition — standard ASTM A217 delivery condition for valve bodies and pressure castings in 450–570 °C steam/hydrocarbon service. ANN: intermediate soft condition supplied for rough machining or weld repair; must be re-normalized/tempered before code service. Yield strength is 330 MPa in N+T versus 280 MPa in ANN.
Sources
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service — ASTM International (2021)
- ASME BPVC Section II Part D — Materials, Properties — ASME (2023)
- ASME B16.34 — Valves, Flanged, Threaded and Welding End — ASME (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- API RP 941 — Steels for Hydrogen Service at Elevated Temperatures — API (2016)
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.