Surface Hardness of Tungsten Cemented Carbide Balls

Tungsten cemented carbide balls are spherical products made from tungsten carbide (WC) powder as the primary component and cobalt (Co) or other metals as a binder, sintered using a powder metallurgy process. They offer high hardness, wear resistance, corrosion resistance, bending resistance, and high-temperature resistance, making them widely used in precision bearings, valve seals, abrasive media, instrumentation, sprayers, water pumps, oilfield equipment, and hardness testers.

The extremely high surface hardness of tungsten cemented carbide balls is one of their core advantages. According to standard specifications for common grades (such as the YG and YT series), tungsten cemented carbide balls typically have a hardness of ≥90.5 HRA (Rockwell A scale). This is equivalent to a Vickers hardness (HV) of approximately 1500-2000 kg/mm² or a Rockwell hardness C scale (HRC) of approximately 85-93, which is much higher than that of ordinary steel balls (HRC is usually 58-65). The hardness value will vary slightly depending on the specific alloy formula (such as cobalt content) and processing technology (such as fine grinding or sintering temperature). For example, some high-performance models can reach HRA 92-94.

The hardness of tungsten cemented carbide balls is usually tested using a Rockwell hardness tester (HRA). The surface must be flat and free of defects. The hardness gradient of cemented carbide is uniform, and the surface and overall hardness are basically the same, so no additional surface hardening treatment is required.

Factors affecting the hardness of tungsten cemented carbide balls include (1) component ratio: the higher the WC content, the higher the hardness, but the toughness may decrease; the higher the cobalt content, the better the toughness but the hardness is slightly lower. (2) sintering process: high temperature sintering can increase the hardness. Vacuum or hydrogen reduction furnace sintering can ensure a dense surface and improve hardness stability, but it needs to be controlled to avoid excessive grain size affecting wear resistance. (3) Application scenarios: At high temperatures (>800°C) or in corrosive media, the surface hardness may slightly decrease, but the overall durability is better than that of steel.

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