ANS:B - hot hardness

A material's capability to resist softening at high temperatures is typically referred to as hot hardness. Hot hardness refers to the ability of a material to maintain its hardness and strength at elevated temperatures. Some materials, especially metals and alloys, tend to soften and lose their mechanical properties when exposed to high temperatures for prolonged periods. However, materials with good hot hardness retain their strength and hardness even at elevated temperatures, making them suitable for high-temperature applications such as cutting tools, dies, and engine components. The other options provided are distinct properties related to materials but are not specifically associated with resistance to softening at high temperatures:

• Hot temper typically refers to the process of heat treating steel to improve its toughness and reduce brittleness.
• Fatigue refers to the weakening of a material due to repeated loading and unloading cycles, which can occur at any temperature, including high temperatures.
• Creep is the tendency of a material to deform slowly and permanently under mechanical stresses at high temperatures, typically at temperatures close to or above their melting point. While creep is related to the behavior of materials at high temperatures, it is not specifically about resistance to softening.