WCB, a carbon steel casting material conforming to ASTM A216 Grade WCB, undergoes a standardized heat treatment process to achieve the required mechanical properties, dimensional stability, and resistance to thermal stress. Below is a detailed description of the typical heat treatment workflow for WCB YD7A1X-16 Butterfly Valve castings:
1. Preheating
- Purpose: To minimize thermal gradients and prevent cracking during subsequent high-temperature treatment.
- Process: Castings are slowly heated in a controlled furnace to a temperature range of 300–400°C (572–752°F).
- Key Parameters: Heating rate is maintained at 50–100°C/hour (90–180°F/hour) to ensure uniform temperature distribution.
2. Austenitizing (Normalizing)
- Purpose: To homogenize the microstructure, refine grain size, and dissolve carbides.
- Process:
- Castings are heated to an austenitizing temperature of 890–940°C (1634–1724°F).
- Held at this temperature for 1–2 hours per 25 mm (1 inch) of section thickness to ensure complete phase transformation.
- Cooled in still air (normalizing) to room temperature.
3. Tempering
- Purpose: To relieve residual stresses, improve toughness, and stabilize the microstructure.
- Process:
- After normalizing, castings are reheated to a tempering temperature of 590–720°C (1094–1328°F).
- Soaked at this temperature for 1–2 hours per 25 mm (1 inch) of thickness.
- Cooled in air or furnace-cooled at a controlled rate to prevent new stress formation.
4. Post-Treatment Inspection
- Purpose: To verify compliance with ASTM A216 standards.
- Process:
- Mechanical testing (e.g., tensile strength, yield strength, hardness).
- Microstructural analysis to ensure uniformity and absence of defects.
- Dimensional checks to confirm stability post-heat treatment.
Optional Steps (Case-Specific)
- Stress Relieving: For complex geometries, an additional stress-relief cycle may be performed at 600–650°C (1112–1202°F) to eliminate residual stresses from machining or welding.
- Controlled Cooling: For thick-section castings, slower cooling rates (e.g., furnace cooling) may be applied during tempering to enhance ductility.
Key Considerations
- Furnace Atmosphere: Neutral or slightly oxidizing atmosphere to prevent decarburization.
- Temperature Uniformity: ±10°C tolerance to ensure consistent results.
- Documentation: Full traceability of heat treatment parameters (time, temperature, cooling rates) for quality assurance.
This process ensures TWS concentric buttterfly valve body D341B1X-16 in WCB castings meet the ASTM A216 requirements for tensile strength (≥485 MPa), yield strength (≥250 MPa), and elongation (≥22%), making them suitable for high-temperature and pressure applications in valves, pumps, and piping systems.
From TWS VALVE, an experienced in producing rubber seated concentric butterfly valve YD37A1X, gate valve, Y-strainer manufacture.
Post time: Apr-02-2025
