Hi guys
I have a question;
What welding procedure is more suitable for welding of Cast Iron (CI)?
I had sevral case of cast iron for welding but some case of welding were not successfull and crack were created in base metal, HAZ or fusion zone. I guess, one of common thing in all cases is high restraint stress, for example repair welding of heat exchanger cap.
Welding Procedure Specification (WPS) that was used in all cases:
- Removing crack or any defects by grinding or machining device
- 100% Penetrant Test (PT) to ensure there are'nt any defects in the base metal
- Bevel: 75 degree
- Preheat 250-300 C
- Welding Electrode: AWS ENiFe-CI or AWS ENi-CI
- Electrode diameter: 2.5 mm
- Current Range Amp: 50-80 A
- In order to decreasing cooling rate; After Welding Cooling Through the Rockwool
If you want to improve the quality of the welding, a heat treatment (tempering at approx. 600-650°C for 1-2 hours with slow cooling) after welding is absolutely necessary.
Okay, thank you for your answer.
As you know the stress relieving improves the quality of the weld, that is used after a healthy or sound weld (a weld free from any crack and defects), while the main problem is formation of crack during the welding!
How can we dissolve it?
If you have cracks during welding, then only two things can help: as much heating as possible before welding and using the most ductile welding filler. For cast iron, nickel is such an filler metal.
You can preheat the joints prior to welding according to carbon equivalent
This solve cracks problem
Dear Mr. Abdou Abdallah Hassan
Yeah, we were heating the workpieces by preheat of 250-300 C.
That's good, therefore we would increase the preheat temperature if it increased according to carbon equivalent.
Thanks a lot.
Dear Hassan,
All the answers are correct. But, in practice, there are some important tricks for a successful repair weld of cast iron.
Even if you are an expert on welding (which you are) I would recommend to you to outsource this work to an experienced expert on repair welding of cast iron.
Above all, I would suggest to detect the root cause of the failure, so you will not encounter such a problem anymore.
Regards
When it comes to welding cast iron (CI), there are a few different welding procedures that can be suitable depending on the specific application and requirements. However, based on the information you provided, it seems that the welding procedure used in your cases may not be the most appropriate for preventing cracking in the base metal, heat-affected zone (HAZ), or fusion zone.
To address the cracking issues, you can consider the following welding procedure modifications:
It is important to note that cast iron welding can be challenging due to its brittle nature and susceptibility to cracking. Therefore, it is recommended to consult with experienced welding professionals or metallurgists who have expertise in cast iron welding to develop a welding procedure specification (WPS) that suits your specific application and can help minimize cracking issues.
Sounds good
Thank you for taking the time to explain your technical answer.
Hello everyone ,
I appreciated all the answers but I agree with doctors R. Beygia and Dr Dzevad Hadzihafizovica.
The use of a cast iron welding specialist is necessary. Several factors influence, in addition to preheating, post heating and PWHT , already recommended, I think that the human factor must be taken into consideration. You need a good, highly qualified cast iron welder who is used to mastering and controlling his weld pool. The height of the arc and the welding energy are factors that only a qualified welder can control.
Otherwise, I would say your WPS is correct
best regards
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