Grahame Collins
9th Dec 2007, 01:14 PM
Hi Everyone,
I really tried to to avoid coming into this one,but I could not help myself. I was going to post this on another thread, but thought it might high jack the thread.I have not come here to tell any one how to suck eggs.
What I do wish to point out that the repair welding of this metal is complex and there is more to it than meets the eye of a DIY welder.
Those comments I saw are based on some contributors experiences. What it will work for some it won't for others.
I do not seek to criticize anyone but I do urge caution to all.
Cast iron can be an extremely difficult metal to weld because of differing reasons.
Cast irons vary in type and in composition. They are several base types.Unless you know the type and its composition its just a guessing game and your chance of success is diminished if you don't know what you are working with.
Cast iron has a very different modulus of elasticity to steel which unfortunately many welders unwittingly compare it to. Cast iron in general will compress well, but does not tolerate tensile or torque loads well.
Cast iron disperses heat held in thick and thin sections at a different rate. It is this uneven cooling that causes much grief among those attempting to weld it. Cracking is the result of stress built up by uneven cooling between thick and thin sections.
Cast iron has the ability to draw in compounds used around it. Oil and carbon from exhaust manifolds come to mind readily.Welding of cast iron is greatly affected by contaminants.
Cast iron contains a super saturation of carbon -up to 4% (yes its is 4% its not my typo) in some cases.Excess carbon is the cause of hardness brittleness and in combination with cooling differentials - cracking.
The above very much determines what process and techniques should be employed to successfully undertake a reliable welding repair on cast iron material.
For those in Brisbane look up the phone and check out Accurate Welding Works at Lytonn. Note that they seem to be the only ones in the book to take on cast iron repair in a big way.
They are also the company I started my apprenticeship with, so I do understand a bit of the subject 40 years down the track. You might ask yourself why there are not a lot of welding works around that do cast iron.
Just some things to think about off the top of my head.
Grahame
I really tried to to avoid coming into this one,but I could not help myself. I was going to post this on another thread, but thought it might high jack the thread.I have not come here to tell any one how to suck eggs.
What I do wish to point out that the repair welding of this metal is complex and there is more to it than meets the eye of a DIY welder.
Those comments I saw are based on some contributors experiences. What it will work for some it won't for others.
I do not seek to criticize anyone but I do urge caution to all.
Cast iron can be an extremely difficult metal to weld because of differing reasons.
Cast irons vary in type and in composition. They are several base types.Unless you know the type and its composition its just a guessing game and your chance of success is diminished if you don't know what you are working with.
Cast iron has a very different modulus of elasticity to steel which unfortunately many welders unwittingly compare it to. Cast iron in general will compress well, but does not tolerate tensile or torque loads well.
Cast iron disperses heat held in thick and thin sections at a different rate. It is this uneven cooling that causes much grief among those attempting to weld it. Cracking is the result of stress built up by uneven cooling between thick and thin sections.
Cast iron has the ability to draw in compounds used around it. Oil and carbon from exhaust manifolds come to mind readily.Welding of cast iron is greatly affected by contaminants.
Cast iron contains a super saturation of carbon -up to 4% (yes its is 4% its not my typo) in some cases.Excess carbon is the cause of hardness brittleness and in combination with cooling differentials - cracking.
The above very much determines what process and techniques should be employed to successfully undertake a reliable welding repair on cast iron material.
For those in Brisbane look up the phone and check out Accurate Welding Works at Lytonn. Note that they seem to be the only ones in the book to take on cast iron repair in a big way.
They are also the company I started my apprenticeship with, so I do understand a bit of the subject 40 years down the track. You might ask yourself why there are not a lot of welding works around that do cast iron.
Just some things to think about off the top of my head.
Grahame