Which deoxidized steel type yields the softest steel with low carbon content as the cheapest and most common grade?

Which deoxidized steel type yields the softest steel with low carbon content as the cheapest and most common grade?

• A. Rimmed steel
• B. Capped steel
• C. Semi-killed steel
• D. Killed steel

Answer: (A)

Understanding how deoxidation type affects softness and cost is key here. Rimmed steel comes from a melt with very little deoxidation, so oxygen isn’t fully removed and a thin oxide rim forms as it solidifies. This results in the softest possible steel with the lowest practical carbon content, giving great ductility and formability. Because the process is simpler and cheaper, rimmed steel is the most economical option and has been the most widely produced. Other deoxidized types—fully deoxidized (killed), semi-killed, or capped—offer greater uniformity and strength and reduce gas porosity, but they trade off softness and cost, so they aren’t as soft or as economical as rimmed steel.

Understanding how deoxidation type affects softness and cost is key here. Rimmed steel comes from a melt with very little deoxidation, so oxygen isn’t fully removed and a thin oxide rim forms as it solidifies. This results in the softest possible steel with the lowest practical carbon content, giving great ductility and formability. Because the process is simpler and cheaper, rimmed steel is the most economical option and has been the most widely produced. Other deoxidized types—fully deoxidized (killed), semi-killed, or capped—offer greater uniformity and strength and reduce gas porosity, but they trade off softness and cost, so they aren’t as soft or as economical as rimmed steel.