Information details
How is the ball of a hard-sealed ball valve generally treated?
Release Time：
2025-08-22
The hardening treatment methods for the ball of a hard-sealed ball valve primarily include surface hardening, chemical heat treatment, thermal spraying, and weld overlay, among others. The specific choice depends on the operational requirements:
Surface Hardening
Flame Hardening: Utilizes an oxygen-acetylene flame to rapidly heat the surface, followed by water cooling to form a martensitic structure. This method achieves high hardness but is prone to deformation, making it suitable for single-piece or small-batch production.
Induction hardening: Heating the surface using an alternating magnetic field, followed by cooling to achieve high and uniform hardness, suitable for mass production.
Chemical heat treatment
Carburizing: Infusing carbon into the surface to form a high-carbon layer, which, after quenching, achieves high hardness and wear resistance but has a longer processing cycle.
Nitriding: Nitrogen atoms are diffused into the surface to form a nitrided layer, resulting in high hardness and wear resistance, but with increased brittleness.
Carbonitriding: Combines the advantages of carburizing and nitriding, with lower processing temperatures and shorter times, offering excellent overall performance.
Thermal Spraying
Plasma Spraying: Melts materials such as metal ceramics and sprays them at high speed onto the surface, resulting in high bonding strength and wear resistance.
Supersonic flame spraying: Produces dense coatings with low porosity, suitable for high-demand applications.
Welding
Manual arc welding: Highly flexible, capable of welding hard alloys, but quality is significantly influenced by human factors.
Automatic submerged arc overlay welding: High efficiency, suitable for mass production.
Other processes
Hard chrome plating: Hardness can reach 60-65 HRC, but the process is complex and large-area treatment is prone to deformation.
Supersonic spraying: Forms an ultra-hard coating on the surface of the sphere, combined with optimized sealing structure to enhance sealing performance.
When selecting a process, consider operating conditions (such as high temperature, high pressure, strong corrosion, etc.) and sealing direction (unidirectional or bidirectional). For example, high-temperature and high-pressure conditions often use carburizing or supersonic spraying processes.
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