Which material is resistant to wear but brittle and is commonly used for drill bits and lathe cutting tools?

• A. High-speed steel
• B. Cast iron
• C. Copper
• D. Bronze

Answer: (A)

High-speed steel is designed to resist wear while keeping hardness at elevated cutting temperatures, which is essential for drill bits and lathe tools. Its alloying elements form hard carbide particles that protect the cutting edge from abrasion, so the tools stay sharp longer even as they heat up during cutting. Cast iron is brittle and wears quickly under cutting, while copper and bronze are relatively soft and don’t provide the sustained edge hardness needed for drilling or turning. That combination of hardness, wear resistance, and heat tolerance makes high-speed steel the best choice for these cutting tools.