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Participant

Join Date: Mar 2011
Posts: 1

Welding Cast Iron and Food toxic

03/11/2011 2:23 AM

1. I have a 99% nickel rod coated with flux. According the MSDS the flux contains barium carbonate, which I believe is used as rat posion. Being a possible contact surface for food, does the flux become part of the weld? Can it be washed away?

2. When welding cast Iron with TIG, the weld puddle sometimes pulses or bubbles at certain place. What causes this? How do I prevent it?

3. Based on Metallurgy why did the technique below led to failure?

Oxy-acetylene torch oxidizing flame attempt to decarburize while brushing with stainless steel. Stacked refractory bricks, to make a temporary oven. Cleaned joint with solvent. Preheated with large propane torch of more than 500 F (temp. crayon), but less than 1414 F (Curie point, checked with magnet). Welded using tig DC - 130 amps (full pedal) ER70S-2 .035" cracked grind out (decarburize) and tried ER70S-7 .035" DC- 100 amps (1/2 pedal) (cracked). Post heated with torch is both cracks.

Best Regards,

Adam Prince

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Guru

Join Date: Oct 2006
Location: Surrey BC Canada
Posts: 1570
Good Answers: 40
#1

Re: Welding Cast Iron and Food toxic

03/11/2011 10:39 PM

This may not be applicable to your situation.

The last time I repaired a cast iron housing was for a piston water pump for a cottage. Water had frozen in it and cracked the housing.

First the crack was ground to a V, then I simply heated the housing in an oven to about 400F, then used oxy-acetylene and brazed it with a bronze rod. I let it sit in a draft free area to cool. No problems with the repair.

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Participant

Join Date: Mar 2011
Posts: 2
#2

Re: Welding Cast Iron and Food toxic

03/11/2011 11:38 PM

There are many different kinds of cast iron... and not all weld the same.....the place where it bubbles where you tried to weld is a dirt pocket " sand inclusion" from the foundry process . grind and clean "you may be chasing it"....flux acts as a sheild for the weldment 1510 degrees C (2750°F)...so safe to say it just needs to be cleaned...most cast after welding needs to be prop. anneled then slow to cooled 1340 held drop to 0 after approx 8 hrs... lots of variables

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Guru

Join Date: Jun 2009
Location: Ontario Canada
Posts: 930
Good Answers: 31
#3

Re: Welding Cast Iron and Food toxic

03/12/2011 9:29 AM

In response to your welding problem JamJam is correct but you can try welding with a Dillon Welding Torch with cast iron rod and the correct flux. Follow the setup and pressures recommended with the Dillon it uses low pressure (4psi) both sides oxy and acetylene. I do not know the composition of this flux but the Dillon torch has a very concentrated and gentle flame and welding cast although not easy can be done successfully depending on the quality of the cast. After a short weld take a pick hammer and tap all around the weld to relive any stress this is an old time technique that helps prevent the cracking. Post heating is also important. Of course any contamination in the casting will stimulate a negative vocabulary in some people.

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