Materials and welding metallurgy

Cast irons

Cast-iron weldability is governed by carbon morphology, matrix, thickness, ageing and service contamination. The critical mechanisms are hard brittle structures at the fusion boundary and the inability of the casting to absorb shrinkage stress. A successful repair therefore starts with diagnosis, not electrode selection.

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Topic overview

Cast-iron weldability is governed by carbon morphology, matrix, thickness, ageing and service contamination. The critical mechanisms are hard brittle structures at the fusion boundary and the inability of the casting to absorb shrinkage stress. A successful repair therefore starts with diagnosis, not electrode selection.

Is repair technically and safely permissible, is the cast-iron type known, and has the cause of the original damage been removed?

Rapid cooling can bind carbon as cementite and create an extremely hard, brittle and unmachinable zone.

Carbon dissolved in austenite can transform to a hard HAZ during cooling and initiate cracking.

What the module covers

  • Cast irons — metallurgy, welding and repair
  • 1. Main cast-iron types and weldability
  • 2. Two distinct repair philosophies
  • 3. Repair workflow
  • Repair checklist
  • Practical rule
Educational content does not replace current standards, approved WPS/WPQR documentation or decisions by competent welding coordination personnel.