Coarse grain steels are preferred in applications where which property is important?

Coarse grain steels are preferred in applications where which property is important?

• A. Lower cost is important.
• B. Very high hardness is required.
• C. Excellent weldability is important.
• D. High temp creep resistance is important.

Answer: (D)

Coarse grain structure reduces the area of grain boundaries, and at high temperatures creep mechanisms rely on diffusion and grain-boundary processes. Fewer boundaries slow these processes, so the material resists long-term deformation under load better when the grains are larger. That’s why coarse grain steels are chosen where high temperature creep resistance is important. The other properties aren’t inherently tied to having coarse grains—coarse grains can even reduce hardness and toughness and don’t guarantee better weldability or lower cost.

Coarse grain structure reduces the area of grain boundaries, and at high temperatures creep mechanisms rely on diffusion and grain-boundary processes. Fewer boundaries slow these processes, so the material resists long-term deformation under load better when the grains are larger. That’s why coarse grain steels are chosen where high temperature creep resistance is important. The other properties aren’t inherently tied to having coarse grains—coarse grains can even reduce hardness and toughness and don’t guarantee better weldability or lower cost.