Approximately what tungsten content range produces red hardness?

Approximately what tungsten content range produces red hardness?

• A. 5-10%
• B. 17-20%
• C. 25-30%
• D. 0.5-1%

Answer: (B)

Red hardness is the ability of a cutting tool material to keep its hardness when it gets hot during use. Tungsten helps with this by forming very hard carbides that resist softening at elevated temperatures, so the tool stays sharp longer under heat. The best balance occurs when tungsten content is around 17 to 20 percent. At this range, enough carbide-forming material is present to create a tough, heat-resistant microstructure without making the metal too brittle. If tungsten is much lower, say 5–10%, there aren’t enough carbide phases to sustain hardness at high temps, so red hardness drops. If tungsten is much higher, like 25–30%, the carbide network can become too dominant, increasing brittleness and reducing toughness, which can also hurt practical red hardness. Very small amounts, such as 0.5–1%, have little impact on high-temperature hardness.

Red hardness is the ability of a cutting tool material to keep its hardness when it gets hot during use. Tungsten helps with this by forming very hard carbides that resist softening at elevated temperatures, so the tool stays sharp longer under heat. The best balance occurs when tungsten content is around 17 to 20 percent. At this range, enough carbide-forming material is present to create a tough, heat-resistant microstructure without making the metal too brittle. If tungsten is much lower, say 5–10%, there aren’t enough carbide phases to sustain hardness at high temps, so red hardness drops. If tungsten is much higher, like 25–30%, the carbide network can become too dominant, increasing brittleness and reducing toughness, which can also hurt practical red hardness. Very small amounts, such as 0.5–1%, have little impact on high-temperature hardness.