Exam Question
Q7
(a) Cast Iron welding is a challenging task, give reasons.
(8)
(b) What alternative repair methods were employed by engine makers on a cast iron casing of an engine?
(8)
Class 2 (2nd Engineer)
MEKM
📅 Mar 2026
Reference Answer
### (a) Reasons for Challenges in Welding Cast Iron
Welding cast iron is an exceptionally challenging metallurgical process due to its inherent chemical composition and physical properties. The primary difficulties arise from its high carbon content and low ductility, leading to a high susceptibility to cracking during and after welding.
1. **High Carbon Content & Formation of Brittle Structures:**
* Cast iron typically contains 2% to 4% carbon, significantly higher than steel. During the welding process, this carbon readily combines with iron in the Heat Affected Zone (HAZ) and the weld fusion zone.
Welding cast iron is an exceptionally challenging metallurgical process due to its inherent chemical composition and physical properties. The primary difficulties arise from its high carbon content and low ductility, leading to a high susceptibility to cracking during and after welding.
1. **High Carbon Content & Formation of Brittle Structures:**
* Cast iron typically contains 2% to 4% carbon, significantly higher than steel. During the welding process, this carbon readily combines with iron in the Heat Affected Zone (HAZ) and the weld fusion zone.
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