In valve manufacturing, both WCB and WCA are cast carbon steel materials in accordance with the ASTM A216 standard, but their chemical composition, mechanical properties and applicable scenarios are significantly different:
1. Chemical composition difference
WCA: Carbon content (C) ≤ 0.25%, stricter restrictions on phosphorus (P) and sulfur (S) impurities (P ≤ 0.035%, S ≤ 0.035%). Improve low-temperature toughness by controlling carbon content and impurities.
WCB: Carbon content (C) ≤ 0.30%, relatively loose restrictions on phosphorus and sulfur (P ≤ 0.04%, S ≤ 0.045%). Focus on strength and weldability in general scenarios.
Key points: WCA has a lower carbon content and stricter impurity control to ensure low-temperature performance; WCB has a slightly higher carbon content and focuses more on room-temperature strength.
2. Difference in mechanical properties
WCA:
Tensile strength ≥415 MPa, yield strength ≥205 MPa.
Advantage: Better low-temperature impact toughness, suitable for low-temperature environments of -46°C.
WCB:
Tensile strength ≥485 MPa, yield strength ≥250 MPa.
Advantage: Higher strength and hardness, but weaker low-temperature toughness than WCA, minimum operating temperature -29°C.
Core difference: WCA sacrifices some strength in exchange for low-temperature toughness, while WCB strengthens strength but has poor low-temperature tolerance.
3. Applicable temperature range
WCA:
-46°C to 425°C (focusing on low-temperature conditions, such as liquefied natural gas and refrigerant systems).
WCB:
-29°C to 425°C (general normal temperature conditions, such as water, steam, oil products).
Note: If the temperature is lower than -29°C, WCA or lower temperature materials (such as LCB) must be selected; if it is higher than 425°C, alloy steel must be used instead.
4. Application scenarios WCA:
Liquefied petroleum gas (LPG), liquid nitrogen, low-temperature refrigeration systems, and other occasions prone to low-temperature brittle fracture.
WCB:
Normal/medium temperature non-corrosive media scenarios such as HVAC, ordinary oil pipelines, and power plant steam systems.
