[ekbmuts]

I'm going to be welding some new cast iron to mild steel. I have 70S-6 available to me as well as R60. I also have some stainless steel rod (308L).

I'm going to TIG weld it.

Should I pre-heat? Weld a few inches and let it cool? Dunk it in a bucket of water as soon as I finish welding?

What should I be looking out for?

Any direction/suggestions as to how to proceed would be appreciated.

THKS.

Jon

[bap_]

I'm not an expert at what you're mentioning, and if fact have never welded cast.

That being said:
1. 308L is not the right wire. Don't bother. You'd be mixing stainless into high carbon parent material.
2. You could go with 309/312 wire for welding dissimilar steel. (probably what I'd try for my first go). I would probably use 312. ER70S could work, but I don't know just taking my best guess.
3. Depending on how thick the cast iron yes, preheat in an oven.
4. Never Dunk it in cold water!?? Seriously only welding practice coupons.
5. Welding isn't hard, it's just cracking that will occur from rapid cooling, or cooling in ambient. If its a thicker casting, preheat, weld, post heat, slowly cool in the oven.

Accept that welding cast may result in failure.

Anyone who knows what they're talking about feel free to shut me down. Just repeating what I know/what I've heard from actual professionals.

Good luck, sounds like you'll learn a bit from this project. Let us know how it goes!

[weldin mike 27]

With cast iron, it depends entirely on what you want the outcome to be. If you need to machine (drill, mill, cut) said welded area, you need to either use a very high nickel filler or an oxy acetylene brazing process. These are specifically designed to keep the carbon from diluting into the weld and causing it to harden. It also creates a ductile weld more suitable for forces higher than just gravity.

If the welded item will just sit there and not be machined or bashed or forced into extreme situations, you can use a low hydrogen consumable (your s6) but the result is a weld that is super hard and not ductile at all. You will need pre heat and peening for this way.

For the oxy acetylene obviously you get pre heat, and peening isn't required. The high nickel can be welded cold,, called the touch method, where you do a small run and don't move on again until you can touch the material. Peening is required here. You can also pre heat with this method. A small run is not more that an inch long. That's important no matter where you are welding with nickel or low hydrogen.

Hope this helps.

Best, Mick

[weldin mike 27]

The high nickle is 99% nickle.

[ekbmuts]

MIke and bap - Thanks for the input. As it isn't a critical item, I'm going to go with what I have to hand, namely that 70S-6. I think I'll preheat with propane or MAPP gas. Again, that's what I can get my hands on on short notice so it will have to do.

When you say peening, what exactly is my procedure? Meaning, do I peen it as soon as I'm done welding? For how long? And what's the end result? Why am I peening? How does it improve/assist my weld? Just a short explanation or even a link to something I can read would suffice.

Thanks again.

Jon

[weldin mike 27]

Peening is hitting the hot metal with a spiky thing like the end of a chipping hammer to stretch out the weld deposit. It allows the metal to grow a little so when the base metal shrinks back after welding, it has less chance of cracking. Do your small run, and as quickly as possible, hit the are with the hammer so that you can see divots in the weld. This means that you are stretching out the material enough. Think of it like using a meat mallet to hit steak, but only in the weld metal.

[weldin mike 27]

Just until you can see that you've hit all of your deposit.... I dunno, maybe 30 times...?

[weldin mike 27]

https://www.lincolnelectric.com/en-us/s ... etail.aspx

[noddybrian]

A needle gun works well for peening & as an added bonus everyone knows your working !

[weldin mike 27]

I used a needle gun every day for years. My ears don't work so well anymore.

[LtBadd]

I used a needle gun every day for years. My ears don't work so well anymore.

What? did you say something? speak up!

[weldin mike 27]

If only it was funny. It did get me out of jury duty, so that's a thing.

[noddybrian]

Needle guns are'nt that bad - I don't hear too well either but it has something to do with my younger days when I was the go to guy for removing wartime concrete structures & tree stumps etc for farmers ! nice one on the exempt jury service though .

[BillE.Dee]

darned turbocharged diesel engines, loud pipes and those dog gone flying machines. I know you're sayin somethin...type slow cuz I don't hear too fast anymore.