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Up Topic Welding Industry / Technical Discussions / how to weld cast iron with TIG method?
- - By michael_sun Date 10-27-2005 00:54
Now we have one problem on a control valve, which material is cast iron.
the supplier of this valve forget to airproof one diameter 6 mm hole, so we plan to weld it by TIG.
I am looking forward to your comments and instruction.
The cast iron is GG40(Germany standard).
Parent - - By Bill M (***) Date 10-27-2005 13:09

You can get a bare nickle rod for welding of cast iron. The problem I have had is that you cannot preheat the part high enough and I have had problems with that passing hydro testing too.

At 6mm, Is it deep enough that you could drill and tap to plug it?
Parent - By brande (***) Date 10-29-2005 04:52
Be real careful here.

Normally, alloys used for cast iron have additional carbon. These are designated by a "CI" reference.

The additional carbon is to reduce contraction and subsequent cracking.

Unfortunately, some filler metal companies use any high nickel alloy, without the extra carbon addition, thinking it is the same (or close), and call it a cast iron alloy.

These do not work always work as well.

My favorite for years has been aluminum bronze, A2

Works well, tensiles out well, and is available as either a stick, mig, or tig alloy.

If you need more info, let me know!!

Good Luck


brande
Parent - By Jim Hughes (***) Date 10-27-2005 16:15
Michael,
you can use a universal 690 cast iron TIG wire. It's made by universal which is a filler material company out of Houston Texas. You should be able to find them on the web. Also UTP has a TIG wire for cast Iron that works good, also on the web. I have personaly used the 690 wire for pumps and it worked well.
Thanks
Jim
Parent - - By michael_sun Date 10-31-2005 01:52
Hi, guys!
Thanks for your comments, it is really helpful to me. According my understanding, it should be ok with nickle base filler metal like stainless wire and bronze wire, and PT check after grinding and welding, am I right?

Note: this valve will be worked under high pressure approx. at 400 bar.
Parent - By brande (***) Date 11-01-2005 02:35
Normal 300 ( 308,309,312 )series stainless can cause problems.310 is a definite no, in my experience.

The available chrome can react with the abundent carbon in cast iron, causing some undesirable chrome carbides at the weld interface. These brittle chrome carbides can crack.

Do yourself a big favor-get a CI (Cast Iron formulated alloy-extra carbon-listed as nickel 55 or 99) or go with aluminum bronze A-2 (my favorite).

There are some techniques that may help as well.

good luck

brande

Parent - By Jim Hughes (***) Date 11-01-2005 20:07
Michael,
Look at the 690 universal wire. Like I mentioned earlier, it has worked very well for cast iron. We have used it for pumps and valves and has passed service tests of 300 psig. We have used it on cyanide service without any failures.
Jim
Parent - By michael_sun Date 11-02-2005 09:03
Hello, everyone!
I already finished this work with bronze wire, and it is really works.
Thanks for your help.

best wishes!

Michael
Up Topic Welding Industry / Technical Discussions / how to weld cast iron with TIG method?

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