What material is characterized as having high toughness but lower hardness compared to carbide?

High-Speed Steel is recognized for its high toughness combined with lower hardness when compared to carbide materials. The toughness of High-Speed Steel allows it to absorb significant stress and resist chipping and breaking, which is crucial during machining operations where tools are subjected to heavy loads.

While carbide offers enhanced hardness, making it suitable for high-speed applications and operations where wear resistance is critical, it can be more brittle. This brittleness can lead to failure in applications involving shock or impact. High-Speed Steel, conversely, balances hardness and toughness, making it versatile for various cutting tools and applications.

Other materials listed, such as cast iron, carbon steel, and tool steel, do not match the specific combination of high toughness and lower hardness relative to carbide offered by High-Speed Steel. Cast iron is more prone to brittleness, carbon steel lacks the necessary toughness for high performance in cutting tools, and while tool steel can exhibit high hardness, it does not emphasize the toughness aspect in the same way High-Speed Steel does.