---
title: "Cast iron versus steel"
subject: "Civil Engineering Materials"
chapter: 8
key: "semester_3/civil_engineering_materials:cast-iron-vs-steel"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/cast-iron-vs-steel
site: BCT Engineering
---

# Cast iron versus steel

Civil Engineering Materials · Chapter 8: Metals and Alloys

- Asked in: 2069 Chaitra, 3 marks; 2072 Chaitra, 2 marks (asked 2 times)
- Video: [Difference Between Pig iron, Wrought iron, Cast Iron, And Steel - An Overview.](https://www.youtube.com/watch?v=rp5_Al2JXAg) — James Sword Engineering 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/cast-iron-vs-steel
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-8

## Question

Differentiate between cast iron and steel (mild steel).

## Short answer

Cast iron (2-4.5% C) is hard, brittle, non-malleable, with low melting point and poor weldability, suited for casting. Mild steel (<0.25% C) is tough, ductile, strong, weldable, used for reinforcement and structures.

## Answer

| Point | Cast iron | Steel (mild steel) |
|---|---|---|
| Carbon content | 2-4.5% | 0.05-0.25% (mild steel), below 2% |
| Nature | Hard, brittle | Tough, ductile |
| Tensile strength | Low (150-300 MPa) | High (400-550 MPa) |
| Compressive strength | High | High |
| Malleability/ductility | Not malleable or ductile | Malleable and ductile |
| Melting point | Lower (1150-1300 C) | Higher (1400-1500 C) |
| Forging/rolling | Cannot be forged or rolled; only cast | Can be forged, rolled and drawn |
| Weldability | Poor | Good |
| Shock/vibration | Poor under impact; absorbs vibration | Resists shock |
| Corrosion | More resistant | Rusts more easily |
| Use | Pipes, columns, manhole covers, machine beds | Reinforcement, beams, frames, bridges |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Cast iron carbon is
   A. 2-4.5%
   B. 0.05-0.25%
   C. Zero
   D. 10%
   Answer: A. Higher. (Key point: Carbon)

2. Cast iron is
   A. Ductile
   B. Hard and brittle, cannot be forged
   C. Easily welded
   D. Forged
   Answer: B. Brittle. (Key point: Nature)

3. Cast iron
   A. Rusts faster
   B. Never
   C. Resists corrosion better than steel
   D. Same
   Answer: C. More resistant. (Key point: Corrosion)

## Related in Civil Engineering Materials

- [Compare cast iron, steel, aluminium](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acompare-cast-iron-steel-aluminium) — Civil Engineering Materials, chapter 8
- [Cast iron versus wrought iron](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acast-iron-vs-wrought-iron) — Civil Engineering Materials, chapter 8
- [Cast iron manufacture and properties](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acast-iron-manufacture-properties) — Civil Engineering Materials, chapter 8
- [Plain carbon steel versus alloy steel](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aplain-carbon-vs-alloy-steel) — Civil Engineering Materials, chapter 8

## Related in other subjects

- [Stress-strain diagram of mild steel](https://www.bctengineer.com/question.md?key=semester_4%2Fstrength_of_materials_mechanical%3Astress-strain-diagram-mild-steel) — Strength of Materials, chapter 2
- [Cast iron pipe with 85% magnesia insulation](https://www.bctengineer.com/question.md?key=semester_2%2Ffundamental_of_thermodynamics_and_heat_transfer%3Acast-iron-pipe-magnesia-insulation-thickness) — Fundamental of Thermodynamics & Heat Transfer, chapter 7
- [Water hammer in elastic cast-iron pipe](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Awater-hammer-cast-iron-pipe) — Hydro Power, chapter 1
- [Cast iron pipe size for given head loss](https://www.bctengineer.com/question.md?key=semester_4%2Fhydraulics%3Acast-iron-pipe-size-for-head-loss) — Hydraulics, chapter 2