Low Carbon Steel, commonly referred to as Mild Steel (MS), is a ferrous alloy containing approximately 0.05% to 0.25% carbon. Its low carbon content makes it highly ductile, easily formable, readily weldable, and cost-effective, making it the most widely used steel worldwide.
Mild steel offers an excellent balance of strength, toughness, workability, and affordability, which explains its dominance across construction, fabrication, automotive, infrastructure, and general engineering sectors.
Chemical Composition
| Element | Typical % |
|---|---|
| Carbon (C) | 0.05 – 0.25 |
| Manganese (Mn) | 0.30 – 0.90 |
| Silicon (Si) | ≤ 0.40 |
| Sulphur (S) | ≤ 0.050 |
| Phosphorus (P) | ≤ 0.050 |
| Iron (Fe) | Balance |
Microstructure
Low carbon steel primarily consists of:
• Ferrite (soft, ductile phase)
• Small amounts of pearlite (strength-contributing phase)
This microstructure results in high ductility, excellent impact resistance, and ease of machining and forming.
Typical Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 370 – 440 MPa |
| Yield Strength | 200 – 250 MPa |
| Elongation | 20 – 30% |
| Hardness | 95 – 120 HB |
| Impact Toughness | High |
| Density | 7.85 g/cm³ |
| Modulus of Elasticity | ~200 GPa |
Heat Treatment Behavior
• Annealing – Improves ductility and softness
• Normalizing – Refines grain structure and uniformity
• Carburizing / case hardening – Hard surface with tough core
• Stress relieving – Reduces residual stresses after fabrication
Common Grades
Indian Standards: IS 2062 (E250, E300, E350), IS 277, IS 1786
International Standards: ASTM A36, ASTM A283/A285, EN 10025 (S235, S275), JIS G3101 (SS400)
Available Product Forms
✔ Plates & sheets (hot rolled / cold rolled)
✔ Coils
✔ Structural sections (beams, channels, angles)
✔ Pipes & tubes (ERW, seamless)
✔ Flats, rounds, squares
✔ TMT bars & wire rods
✔ Galvanized & pre-painted steel
Applications
Construction: Buildings, bridges, sheds, frameworks, scaffolding
Automotive: Chassis, body panels, structural components
Manufacturing: Machinery frames, tools, fabricated parts
Piping: Water pipelines, low-pressure gas pipelines
Advantages
✔ Low cost and wide availability
✔ Excellent weldability and formability
✔ Easy machining and fabrication
✔ Good strength-to-weight ratio
✔ Ideal for mass production
Limitations
⚠ Lower strength than alloy steels
⚠ Poor corrosion resistance without coating
⚠ Not hardenable by quenching
⚠ Limited high-temperature performance
Comparison: Mild vs High Carbon Steel
| Property | Mild Steel | High Carbon Steel |
|---|---|---|
| Carbon Content | 0.05 – 0.25% | 0.6 – 1.0% |
| Ductility | High | Low |
| Weldability | Excellent | Poor |
| Hardness | Low–Moderate | High |
| Typical Use | Structural & fabrication | Tools, springs |
Why Choose Mild Steel
Low carbon steel is the backbone of modern infrastructure and manufacturing. Its unmatched combination of ductility, weldability, machinability, and cost-effectiveness makes it the preferred material for structural, automotive, industrial, and general engineering applications worldwide.