tig welding cast

Date 07-19-2010 15:12

Sure; it can be done. However; due to the lack of cleanliness most of my cast repairs have been mired in; stick has been my choice for welding cast. Nickel rod.........oh jeez; tons of specialty mfg. out there; Muggyweld is expensive but good. If the casting is really critical I'd suggest repair with stitching rather than welding.

By supermoto (***)

Date 07-19-2010 15:19

Make sure it is cast iron, becasue I have GTAW some cast steel and it does pretty good with some Ni filler. Can be pretty dirty though.

By Tommyjoking (****)

Date 07-19-2010 18:00

Cast steels yea....Iron I just cannot imagine it working out too good, never done it.

This is the best way to go far as I am concerned: http://www.cut-like-plasma.com/info_welding_cast_iron.htm (the rod is expensive and I do not know anyone who stocks it).

Other then that stick weld it with a quality rod....

By DaveBoyer (*****)

Date 07-21-2010 03:17

The guy doing the Henrob demos said discarded cast iron piston rings work fine for filler. Get them from an engine rebuilder.

By Tommyjoking (****)

Date 07-21-2010 21:36

Dave I imagine uncoated iron piston rings would work good. I have never had a cast repair that small tho..... The rods I have used were always square bar....most of the time a repair needed a filler like 1/4 or bigger because it was thick and we had it beveled out for full pen. I do not know if the henrob torches are worth it, not to say they are not what they say they are...we always used what ever we had in the shop. If it is crucial/valuable/irreplaceable it is the ONLY method I would consider. I am not super good at it but it just takes practice like anything else. I think it is pretty wild what Denny is proposing with the MIG....just goes to prove you can learn something valuable everyday when you listen.

By DaveBoyer (*****)

Date 07-23-2010 02:40

I got a used Dillon MkIII, same as a Henrob. Worth it? I don't know. It will do everything they claim, I saw the guy do it. It however doesn't do it by itself. That guy could probably do a lot of what He is showing with any other torch. The fine cutting is possible due to the seperation of the heating flame & the Oxy jet.

I have some 3/8" square cast iron filler rod, but never used it. It is OK if I never need to use it.

Denny's MIG process is interesting, never heard of that before.

By yorkiepap (***)

Date 07-21-2010 12:07

Hey weaver,
Several years ago reading up on cast iron, I found interesting data & results with a technique called: "Cold Welding Cast Iron With MIG". There were references in an older Lincoln book & some postings on several websites. I went to my brothers' engine shop & picked up a few intake & exhaust manifolds he had scrapped & did a couple months of experimenting. I made notations in my logbook w/results & parameters used.

My technique involves a good cleaning of the weld area w/wire wheel or light grinding, a good bevel of the entire crack, & either backgas or solar flux. The process dictates tacking in several positions to secure the joint & then short beads, not exceeding 1/2" to complete the joint. Each application of weld has to be peened immediately after welding & allowed to cool back to room temperature. This keeps the casting cool & after each bead, you can remove your glove & lay your hand on the cast & the cast would only feel warm to the touch. This technique eliminates the dreaded "tinkle"(another crack) that occurs with heating/cooling of cast iron.

I use 309L(.01 carbon) SS wire, .030, 98/2(AR/CO2) @ 18cfh, heat between 80-100A depending on thickness, & "pull"(drag) the puddle. You can use any combo of gas not exceeding 5% CO2(ex:95/5). So far, I have had complete success & no issues. Attached photos are a couple exhaust manifolds I did for a foreign car dealer from (2) Rolls Royce autos. The dealer was quite pleased as replacement manifolds were very expensive.

Hope this may give you some food-for-thought....

Denny

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By supermoto (***)

Date 07-21-2010 14:12

I have always heard of two ways people have done it; the hot and the cold way. Never seen anyone actually do it the cold way but seems like you have done a great job and the experimenting to prove it. Good info to remember.

How well do you need to clean the inside? I am assuming that it didn't completely penetrate.

By yorkiepap (***)

Date 07-21-2010 16:55

Hey supermoto,
Yes, it took quite a bit of experimenting to establish solid weld joints with both penetration & total fillet. I cleaned the interior of the joint to bare & used solar flux if needed rather than purging, & since these were exhaust manifolds, I lightly ground the interior to smooth after I finished. This allows an uninterrupted flow of exhaust gasses that may be caused by excessive weld in the inside. As far as penetration, it was excellent as I beveled to within .040 of the interior & the drag of the puddle gave superb penetration.

I have done several manifolds for a marine dealer from customers who didn't fully drain their boat engines & caused some brutal cracks on their manifolds with complete success. Also, probably a half-dozen cast iron stoves that had various cracks in the door or to the tops or legs.

It takes some serious practice & making note of every action/reaction.....the technique is not hard. Clean joint area is mandatory, as is the gas mix not exceeding 5% CO2.

Anyway, just wanted to provide a technique I find successful & maybe will help others with a cast repair. BTW...... never ASS...U...ME.

Denny