The percentage of carbon in low carbon steel is:
Try it first: pick an option, then read the explanation.
Understanding Steel Classification by Carbon Content
Plain carbon steels are classified into three main categories based on their carbon content, as this is the primary factor that determines their mechanical properties like strength, hardness, and ductility.
Low Carbon Steel (Mild Steel)
Carbon Range: Generally defined as having a carbon content between 0.05% and 0.25%.
Properties: This type of steel is relatively soft, ductile, and tough. It is not extremely strong but is easy to shape, form, and weld. Its surface can be hardened through carburizing if needed. It is the most common and least expensive form of steel.
Detailed Analysis of the Options
Let's place each option within the standard classification of carbon steels.
| Steel Type | Typical Carbon Range | Properties |
|---|---|---|
| Low Carbon (Mild) Steel | 0.05% - 0.25% | Soft, ductile, easily welded, tough |
| Medium Carbon Steel | 0.25% - 0.60% | Stronger, harder, less ductile |
| High Carbon Steel | 0.60% - 1.5% | Very strong, very hard, brittle |
Evaluating the Choices:
- (A) 0.05%: This is at the very low end of the mild steel range, often considered an ultra-low carbon steel.
- (B) 0.15%: This value falls squarely in the middle of the accepted range for low carbon/mild steel (0.05% - 0.25%). It is a very typical and representative value.
- (C) 0.3%: This value is at the upper limit of low carbon steel and is more accurately classified as the beginning of the medium carbon steel range.
- (D) 0.5%: This is firmly within the medium carbon steel range.
Given the options, 0.15% is the most representative and common value for what is generally considered low carbon steel.