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Welding cast iron.

03-26-2010, 08:18 PM
How do you do it? I've never done it before but I'm sure there is a specific rod or wire or something I need and possibly a different technique than what I'm used to welding steel.

03-26-2010, 08:21 PM
new or repair, what welder are you using

03-26-2010, 08:30 PM
new or repair, what welder are you using
It is a repair and I'm not sure which welder I will be using. Which welder is best? I have mig, ac stick, gas flux core, gasless flux core, DC+ and DC- stick and have access to DC tig.

I don't know what is best or where to start. A student asked me if he brought something in could he and I fix it. I told him both of us would have to LEARN and that I would be finding out what process welder to use and electrode and such.

BTW, it is a vice. He said it don't have to be pretty just strong.

03-26-2010, 08:46 PM
There are many different grades of cast iron, some more weldable than others. And it is difficult to tell them apart
But 1. Clean the metal: 2.grove out the crack 3.Preheat if possible. evenly heat to hot, like 400-500f 4. stick with Nickel Rod (Ni Rod) or you can Mig
But keep peening the weld bead so it help with the shrinkage of the weld
but do it consistently
Bottom line one day it weld fine another forget it I Have welded a lot of C/I
PS always keep the temp up on the project till done welding

03-26-2010, 08:55 PM
Bluuesman, also if you are going to Mig it make sure you use a V Nitt
technic as you would in Miging a inside corner verticaly going up
if you dive into it with deep sharp penitration, instead of broad even disturbution
the weld will shrink quicker then the cast and pull away. in which leave a void or crack along side the new weld

03-26-2010, 08:58 PM
I have never had sucess with cast Iron. Everey time Itry to weld it, It cracks next to the weld. Can any one shead some light on this??

03-26-2010, 09:08 PM
you can Tig but you would want to do it in AC as to have control of the balance
DC would be to hot to deep to quick, with AC you can use a larger Tungsten and throw all you heat into the Tungsten instead of the Cast. hope this Helps

03-26-2010, 11:50 PM
I've had good luck with the nickel rods from tractor supply on cast iron.

03-27-2010, 06:19 AM
I agree with the nickel rods. The real trick is preheat and cool slowly. If the part is small enough put it in an oven to preheat (as hot as the oven can go), take it out and weld it and put it back in the oven. Turn the oven off and let everything cool slooooooooooooowly.

03-27-2010, 06:23 AM
But in all Honesty, Wait till the Wife goes somewhere for a few Hours
or you just end up in a debate with her, if you are going to use the oven clean well

03-27-2010, 06:35 AM
devilhornsClean well before or after?devilhorns

03-27-2010, 06:35 AM
here is what an old timer tight me for larger C/I (and have done over the years)
stack blocks to make a cube around the unit cover with a steel sheet
leave 2 blocks empty on back side low to ground and the front side open enough for you salimander heater. start heater away from opening as unit gets hotter move salimander closer and keep checking with infered thermomitor, you can things into the 4 to 600 range

03-27-2010, 07:01 AM
Probably a better idea than the wife's oven. Any method that will evenly heat the piece to 400-500 degrees should work.

03-27-2010, 12:46 PM
on another note of Cast Iron, I take it the Vise break is severed. so this will not contain to you
but if you are fixing a crack in C/I always drill a hole at the end of crack so it will not continue to grow, and just fill the hole on the end of your weld run

03-27-2010, 06:56 PM
Short welds are also better than long ones. So just do a short section. Tap the weld warm the whole thing back up again weld a short distance tap the weld, and repeat. Letting it cool slowly is also key. My dad would wrap larger parts in fiberglass insulation so they would cool slower.

03-28-2010, 10:41 AM
Bluesman we have had some luck with the pre-heat&slow cool down w/nickle rod on storm sewer catch basin grates&other items that are subjected to room room temp. but things that are to be used in a hot & cold application tend to re-crack GOOD LUCK.

03-28-2010, 09:54 PM
The other day I had to make a repair and one piece was mild steel and the other was some sort of cast. I tried to tig weld it with regular mild steel rod (forget what type it is) and sure enough it cracked as it cooled. I then turned around and welded it with stainless steel rod and worked like a charm. Something to try, YMMV.

05-17-2010, 06:35 PM
I will soon be welding a cast iron cutout on my truck and wanted to know what wire to use and how to weld it. Looks like I will be using either nickel or stainless. Thanks!

05-18-2010, 12:36 AM
I just welded a 4-wheeler hitch back togeter that was cast. We used 6010 for tack and root pass and then welded over the top with 7018.

Did a lot of preheating with torch. Got it cherry red and then welded. As it cooled during the welding process we heated it back up to temp. After it was finished welding we lightly heated it and made sure it cooled VERY VERY VERY slowly.

Worked like a charm. You can see where we welded it and it isn't really smooth, but it is strong. We load tested it and it hasn't broken so far.

05-19-2010, 06:00 AM
Does not always happen with cast so congratulations
One other thing to try to make it cool slow is bury it in dry sand.

Dave Trunks
05-24-2010, 02:41 PM
All good answers but just one little issue that nobody has raised is the weld prep. If you use a grinder to do the weld prep be sure to leave some excess material so that you can take the last of the material out with a tungsten burr. Useing a grinder only on the prep will draw carbon to the surface of the prep thereby making an already high carbon steel even harder to weld. Use high nickel rods or Braze Welding techniques for succcess in welding cast irons and for volume welding of cast irons there are some great products available these days albeit expensive ones. Cheers all

05-24-2010, 02:59 PM
Now that's a tip I hadn't heard before! Thanks.

Art R.