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How do you determine the type of cast iron you are dealing with?


Frequently Asked Questions

Determination of the type of cast iron you wish to weld is vital if you intend to produce a sound weld with suitable properties. A useful checklist is:

  1. Check all paperwork and documentation for specifications or trade names that describe the iron casting.
  2. Contact the iron founder for confirmation.
  3. Study a section under the optical microscope in accordance with BS EN ISO 945-1:2008 (you may need assistance from a qualified metallurgist to carry out this operation).
  4. Carry out a chemical analysis and a hardness check to determine the iron type and condition.
  5. If a weld repair is under consideration, it may be prudent to consult a design authority to confirm the advisability of the operation.

TWI can provide assistance with chemical analysis, hardness testing, metallographic examination, cast iron weld repair and development of welding procedures for cast iron components. Contact us for more information on any of these topics.

Further information available in:

Welding of cast irons- a guide to best practice

Microstructure of cast irons-Part 1:  Graphite classification by visual analysis, BS EN ISO 945-1:2008, British Standard Institute, United Kingdom. e-mail:

ISBN 978 0 580 70831 2

For more information please email: