Valve Material Chemical Composition & Mechanical Properties
Complete reference chart for chemical composition (%) and mechanical properties of all common valve body casting, forging, and bolting materials. Covers carbon steel, alloy steel, stainless steel, and special alloys per ASTM standards. Published by Supreme Valves India.
Quick Reference
- Carbon Steel Castings: WCB (general), WC6 (0.5Mo), WC9 (2.25Cr-1Mo), C5 (5Cr-0.5Mo), LCB/LCC (low temp)
- Stainless Steel Castings: CF8 (304), CF8M (316), CF3 (304L), CF3M (316L), CN7M (Alloy 20)
- Carbon Steel Forgings: A105 (general), F6 (13Cr), F11 (1.25Cr-0.5Mo)
- SS Forgings/Bar: 304, 316, 304L, 316L, 321, 410, 420, 430
- Bolting: B7/B7M (Cr-Mo), B8/B8M (SS304), L7/L7M (low temp), 2H/2HM (nuts)
Chemical Composition (% by weight)
Maximum or range values per applicable ASTM standard. All elements in weight percent.
| Material | C max. |
Mn max. |
P max. |
S max. |
Si max. |
Cr | Mo | Ni | Cu max. |
|---|---|---|---|---|---|---|---|---|---|
| Carbon Steel & Alloy Steel Castings (ASTM A216 / A217) | |||||||||
| WCB | 0.30 | 1.00 | 0.04 | 0.045 | 0.60 | ≤0.5 | ≤0.2 | ≤0.5 | ≤0.3 |
| WC6 | 0.20 | 0.5–0.8 | 0.04 | 0.045 | 0.60 | 1.0–1.5 | 0.45–0.65 | 0.5 | 0.5 |
| WC9 | 0.18 | 0.4–0.7 | 0.04 | 0.045 | 0.60 | 2.0–2.75 | 0.9–0.12 | 0.5 | 0.5 |
| C5 | 0.20 | 0.4–0.7 | 0.04 | 0.045 | 0.75 | 4.00–6.50 | 0.45–0.65 | 0.5 | 0.5 |
| LCB | 0.30 | 1.00 | 0.04 | 0.045 | 0.60 | 0.5 | 0.2 | 0.5 | 0.3 |
| LCC | 0.25 | 1.20 | 0.04 | 0.045 | 0.60 | 0.5 | 0.2 | 0.5 | 0.3 |
| Stainless Steel Castings (ASTM A351) | |||||||||
| CF8 | 0.08 | 1.50 | 0.04 | 0.04 | 2.00 | 18–21 | 0.5 | 8–11 | – |
| CF8M | 0.08 | 1.50 | 0.04 | 0.04 | 1.50 | 18–21 | 2–3 | 9–12 | – |
| CF3 | 0.03 | 1.50 | 0.04 | 0.04 | 2.00 | 17–21 | 0.5 | 8–12 | – |
| CF3M | 0.03 | 1.50 | 0.04 | 0.04 | 1.50 | 17–21 | 2–3 | 9–13 | – |
| CN7M | 0.07 | 1.50 | 0.04 | 0.04 | 1.50 | 19.0–22.0 | 2–3 | 27.0–30.5 | 3.0–4.0 |
| Carbon Steel & Alloy Steel Forgings (ASTM A105 / A182) | |||||||||
| A105 | 0.35 | 0.60–1.05 | 0.04 | 0.05 | 0.35 | ≤0.3 | ≤0.12 | ≤0.4 | ≤0.3 |
| F6 | 0.15 | 1.00 | 0.04 | 0.03 | 1.00 | 11.5–13.5 | – | ≤0.5 | – |
| F11 | 0.1–0.2 | 0.3–0.8 | 0.04 | 0.04 | 0.5–1.0 | 1.0–1.5 | 0.44–0.65 | – | – |
| Stainless Steel Forgings & Bar (ASTM A182 / A276) | |||||||||
| 304 | 0.08 | 2.0 | 0.04 | 0.03 | 1.0 | 18.0–20.0 | – | 8.0–11.0 | – |
| 316 | 0.08 | 2.0 | 0.04 | 0.03 | 1.0 | 16.0–18.0 | 2.0–3.0 | 10.0–14.0 | – |
| 304L | 0.035 | 2.0 | 0.04 | 0.03 | 1.0 | 18.0–20.0 | – | 8.0–13.0 | – |
| 316L | 0.035 | 2.0 | 0.04 | 0.03 | 1.0 | 16.0–18.0 | 2.0–3.0 | 10.0–15.0 | – |
| 321 | 0.08 | 2.0 | 0.04 | 0.03 | 1.0 | 17.0 min. | – | 9.0–12.0 | – |
| 410 | 0.15 | 1.0 | 0.04 | 0.03 | 1.0 | 11.5–13.5 | – | – | – |
| 420 | >0.15 | 1.0 | 0.04 | 0.03 | 1.0 | 12.0–14.0 | – | – | – |
| 430 | 0.12 | 1.0 | 0.04 | 0.03 | 1.0 | 16.0–18.0 | – | – | – |
| Bolting Materials (ASTM A193 / A194 / A320) | |||||||||
| B7 | 0.37–0.49 | 0.65–1.10 | 0.035 | 0.04 | 0.15–0.35 | 0.75–1.20 | 0.15–0.25 | – | – |
| B7M | 0.37–0.49 | 0.65–1.10 | 0.035 | 0.04 | 0.15–0.35 | 0.75–1.20 | 0.15–0.25 | – | – |
| 2H | >0.4 | 1.00 | 0.04 | 0.05 | 0.40 | – | – | – | – |
| 2HM | >0.4 | 1.00 | 0.04 | 0.05 | 0.40 | – | – | – | – |
| B8 | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 | 18.0–20.0 | – | 8.0–10.5 | – |
| B8M | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 | 16.0–18.0 | 2.0–3.0 | 10.0–14.0 | – |
| 8 | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 | 18.0–20.0 | – | 8.0–10.5 | – |
| L7 | 0.38–0.48 | 0.75–1.00 | 0.035 | 0.04 | 0.15–0.35 | 0.80–1.10 | 0.15–0.25 | – | – |
| L7M | 0.38–0.48 | 0.75–1.00 | 0.035 | 0.04 | 0.15–0.35 | 0.80–1.10 | 0.15–0.25 | – | – |
Note: Values are maximum unless a range is shown. Always refer to the applicable ASTM standard edition for exact requirements. "–" indicates element not specified or not significant.
Mechanical Properties
Minimum tensile strength, yield strength, elongation, reduction of area, and hardness per applicable ASTM standard.
| Material | Tensile Strength (MPa min) |
Yield Strength (MPa min) |
Elongation (% min) |
Red. of Area (% min) |
Hardness (BHN) |
|---|---|---|---|---|---|
| Carbon Steel & Alloy Steel Castings | |||||
| WCB | 485 | 250 | 22 | 35 | – |
| WC6 | 485 | 275 | 20 | 35 | – |
| WC9 | 655 | 275 | 20 | 35 | – |
| C5 | 620 | 415 | 18 | 35 | – |
| LCB | 450 | 240 | 24 | 35 | – |
| LCC | 485 | 275 | 22 | 35 | – |
| Stainless Steel Castings | |||||
| CF8 | 485 | 205 | 35 | – | – |
| CF8M | 485 | 205 | 30 | – | – |
| CF3 | 485 | 205 | 35 | – | – |
| CF3M | 485 | 205 | 30 | – | – |
| CN7M | 425 | 170 | 35 | – | – |
| Carbon Steel & Alloy Steel Forgings | |||||
| A105 | 485 | 250 | 22 | 30 | 187 |
| F6 | 485 | 275 | 18 | 35 | 143–187 |
| F11 | 485 | 275 | 20 | 40 | 179–217 |
| Stainless Steel Forgings & Bar | |||||
| 304 | 515 | 205 | 30 | 50 | – |
| 316 | 515 | 205 | 30 | 50 | – |
| 304L | 485 | 170 | 30 | 50 | – |
| 316L | 485 | 170 | 30 | 50 | – |
| 321 | 515 | 205 | 30 | 50 | – |
| 410 | 480 | 275 | 16 | 45 | – |
| 420 | – | – | – | – | 255 |
| 430 | 415 | 207 | 20 | 45 | – |
| Bolting Materials | |||||
| B7 (≤2½") | 860 | 720 | 16 | 50 | – |
| B7M | 690 | 550 | 18 | 50 | 235 |
| 2H (Nut) | – | – | – | – | 248–352 |
| 2HM (Nut) | – | – | – | – | 159–237 |
| B8 (CL1) | 515 | 205 | 30 | 50 | 223 |
| B8M (CL1) | 515 | 205 | 30 | 50 | 223 |
| 8 (Nut) | – | – | – | – | 126–300 |
| L7 (≤2½") | 860 | 725 | 16 | 50 | – |
| L7M | 690 | 550 | 18 | 50 | 235 |
Note: Values are minimum unless a range is shown. Bolt material properties vary by diameter — values shown are for ≤2½" (65mm) diameter. For larger diameters, refer to the applicable ASTM standard. BHN = Brinell Hardness Number.
Casting ↔ Forging ↔ Wrought Equivalents
Cross-reference between cast, forged, and wrought designations for common valve materials.
| Type | Casting (A216/A217/A351) | Forging (A105/A182) | Wrought/Bar (A276/A479) | Application |
|---|---|---|---|---|
| Carbon Steel | WCB | A105 | – | General service, -29 to 425°C |
| 1.25Cr-0.5Mo | WC6 | F11 | – | High temp steam, up to 538°C |
| 2.25Cr-1Mo | WC9 | F22 | – | High temp steam, up to 593°C |
| 5Cr-0.5Mo | C5 | F5 | – | High temp, sulfur crude, up to 649°C |
| Low Temp CS | LCB | LF2 | – | Low temperature, down to -46°C |
| SS 304 | CF8 | F304 | 304 | General corrosive, cryogenic |
| SS 316 | CF8M | F316 | 316 | Chloride, seawater, chemical |
| SS 304L | CF3 | F304L | 304L | Welded, intergranular corrosion |
| SS 316L | CF3M | F316L | 316L | Welded, chloride + weld service |
| Alloy 20 | CN7M | – | N08020 | Sulfuric acid, phosphoric acid |
| 13Cr | CA15 | F6a | 410 | Mild corrosion, erosion resistant |
Why does this matter? When specifying a valve, the body material is specified as a casting grade (e.g., WCB for cast body) or forging grade (e.g., A105 for forged body). The trim (stem, disc, seat) may use wrought/bar grades (e.g., 316 bar for a stem). Knowing the equivalents ensures correct material matching across all valve components.
Standard Bolt + Nut Pairing Guide
| Service | Stud Bolt | Nut | Temperature Range | Notes |
|---|---|---|---|---|
| Standard (CS body) | A193 B7 | A194 2H | -29 to 425°C | Most common pairing for WCB valves |
| Standard (HIC/SSC) | A193 B7M | A194 2HM | -29 to 425°C | Max hardness 22 HRC for NACE MR0175 |
| SS body (corrosive) | A193 B8M | A194 8M | -196 to 425°C | SS316 bolts for CF8M body |
| SS body (general) | A193 B8 | A194 8 | -196 to 425°C | SS304 bolts for CF8 body |
| Low temperature | A320 L7 | A194 4 | -101 to 425°C | Cr-Mo, impact tested at -101°C |
| Low temp (HIC/SSC) | A320 L7M | A194 7M | -101 to 425°C | Max hardness 235 BHN for NACE |
| High temperature | A193 B16 | A194 4 | -29 to 538°C | Cr-Mo-V, for high-temp flanges |
NACE MR0175 / ISO 15156: For sour service (H₂S), bolt hardness must not exceed 22 HRC (237 BHN). Use B7M/2HM or L7M/7M pairings. Standard B7/2H may exceed this limit and are NOT suitable for sour service without hardness verification.
Frequently Asked Questions
What is the chemical composition of WCB carbon steel?
WCB (ASTM A216 Grade WCB) chemical composition: C 0.30% max, Mn 1.00% max, P 0.04% max, S 0.045% max, Si 0.60% max, Cr ≤0.5%, Mo ≤0.2%, Ni ≤0.5%, Cu ≤0.3%. Mechanical properties: Tensile strength 485 MPa min, Yield strength 250 MPa min, Elongation 22% min, Reduction of area 35% min. WCB is the most common valve body casting material for general service (-29 to 425°C).
What is the chemical composition of CF8M (SS316 casting)?
CF8M (ASTM A351) chemical composition: C 0.08% max, Mn 1.50% max, Si 1.50% max, Cr 18–21%, Mo 2–3%, Ni 9–12%. Mechanical properties: Tensile 485 MPa min, Yield 205 MPa min, Elongation 30% min. CF8M is the cast equivalent of wrought SS316. The 2–3% molybdenum provides superior pitting and crevice corrosion resistance compared to CF8 (SS304).
What is the difference between CF8 and CF8M?
CF8 = cast SS304 (18Cr-8Ni, no Mo). CF8M = cast SS316 (18Cr-12Ni-2Mo). The key difference is 2–3% Molybdenum in CF8M, which provides significantly better resistance to pitting, crevice corrosion, and chloride stress corrosion cracking. Use CF8 for general corrosive service; use CF8M when chlorides, seawater, or aggressive acids are present.
What is ASTM A193 B7 bolt material?
A193 B7 is a Cr-Mo alloy steel bolt/stud material. Composition: C 0.37–0.49%, Cr 0.75–1.20%, Mo 0.15–0.25%. Mechanical properties (≤2½"): Tensile 860 MPa min, Yield 720 MPa min, Elongation 16%, Reduction of area 50%. B7 is the most common stud bolt for flanged valve connections. For sour service (NACE MR0175), use B7M (max 235 BHN / 22 HRC).
What is the difference between A105 and WCB?
A105 = forged carbon steel (ASTM A105). WCB = cast carbon steel (ASTM A216). Both are used for valve bodies. A105 is forged (higher strength, better grain structure, used for small valves per API 602, flanges, fittings). WCB is cast (complex shapes, larger sizes, used for API 600/6D valves). A105 has slightly higher carbon (0.35% vs 0.30%) and higher hardness limit (187 BHN). Both have similar tensile/yield strength.
What bolt material to use with SS316 valves?
For CF8M (SS316) valve bodies: Use A193 B8M studs + A194 8M nuts for corrosive environments where bolt material must match the body. For non-corrosive environments, A193 B7 + A194 2H is acceptable and more economical. For low-temperature service, use A320 L7M. For sour service, use B7M/2HM (hardness ≤22 HRC). Always check the project specification.
Related Technical Resources
Valve Material Selection Guide
WCB vs SS316 vs Duplex — temperature limits, corrosion chart, cost comparison
Valve Test Pressure ChartAPI 598 hydrostatic test pressures, ASME B16.34 P-T ratings
P-T Rating CalculatorInteractive ASME B16.34 lookup for all materials and classes
Valve Standards ReferenceAPI 600, API 602, ASME B16.34, material standards reference
Need Valves in Specific Materials?
Supreme Valves India supplies valves in all materials listed above — WCB, SS316, Duplex, Alloy Steel, and exotic alloys. Complete material traceability with EN 10204 3.1 certificates.