Alan, More info = More replies…………….

Bear..

The only way to "WELD" cast iron is using oxy /acetylene. Any other systenm is adhesion on a microscopic level.The problem is the free carbon available in the cast iron which has a tendency to embrittle any filler material. The use of nickel helps to reduce this tendancy,because it does not combine with the carbon.

I agree with Michael Darby. Any method other than ox/ac welding with cast iron rod will give unsatisfactory results.

Mig and Tig are particularly bad because of the very concentrated heat. The mass quench effect of the base metal will create a hard zone that is extremely brittle. Even with ox/ac mass quench can result in hard zones that require post weld anneal to restore machinability.

http://www.lincolnelectric.com/en-gb/support/welding-how-to/Pages/welding-cast-iron-detail.aspx

He would have used a nickel based filler which as I stated earlier would not have "Welded" the joint " because the filler could not use up the free carbon it would have "adhered" to the iron molecules in the casting forming a nickel rich iron moleclue. the problem with this is that you have free carbon atatchments to the iron creating brittle edges within the structure of the material hence the post heating cycle to attempt to reduce the brittle edges

Alan ,

In my experience thorough and sustained both pre and post heating are essential if the repair is to stand any chance of permanence . The last CI item I welded was a bench vice . I thoroughly pre- heated , then used a No 25 nozzle on o-a to complete the weld , before carefully put the vice in a dustbin full of sand for 24 hours . Vice is still in use many years later . If you know anyone with oxy-acet that can do the work for you , but who lack the materials , I can supply you small amount of rod and flux to complete your work for the cother of the postage . Alternatively you may find Cast Iron Welding Services in Coalville on 01530 811308 ( no connection ) helpful .