Toughness is best defined as which of the following?

Toughness is best defined as which of the following?

• A. The maximum stress a material can withstand before yielding.
• B. The rate at which a material heats up under thermal loading.
• C. A combination of strength and ductility, i.e., the ability to absorb energy and deform plastically before fracturing.
• D. The ability of a material to resist corrosion in a reactor environment.

Answer: (C)

Toughness is about how much energy a material can absorb before it breaks, which comes from having both strength and the ability to deform plastically. In a stress–strain plot, toughness is the area under the curve up to fracture, meaning a material that is strong but very brittle may not absorb much energy before fracturing, while a material that can deform a lot (ductile) and carry load can absorb more energy. So toughness really describes a combination of strength and ductility—the ability to absorb energy and deform plastically before fracturing. The other options don’t fit: the maximum stress before yielding is yield strength, not toughness; the rate of heating relates to thermal response; and corrosion resistance concerns environmental durability rather than resistance to fracture under load.

Toughness is about how much energy a material can absorb before it breaks, which comes from having both strength and the ability to deform plastically. In a stress–strain plot, toughness is the area under the curve up to fracture, meaning a material that is strong but very brittle may not absorb much energy before fracturing, while a material that can deform a lot (ductile) and carry load can absorb more energy. So toughness really describes a combination of strength and ductility—the ability to absorb energy and deform plastically before fracturing. The other options don’t fit: the maximum stress before yielding is yield strength, not toughness; the rate of heating relates to thermal response; and corrosion resistance concerns environmental durability rather than resistance to fracture under load.