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Mig weld steel on cast iron manifold?

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Old 07-26-2010, 11:15 AM
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Default Mig weld steel on cast iron manifold?

I did an internet search, but I get different techniques, methods, and ideas. Anybody got real world examples?

The project is a 99 Pontiac Firebird V6 with a front mounted, twinscroll turbocharger. I have a cast iron exhaust manifold from a Pontiac Grand Prix 3.8 GTP that is being flipped around and used a turbo manifold for the driver's side. The passenger side was custom fabbed with 304 SS and Schedule 10 bends. I want to attach a WG bung made of thick stainless steel and hang the WG off the backside of each manifold and angle the exhaust straight down in order to vent to atmosphere. This will save alot of room and possibly reduce heat in the engine bay. The problem is that I have to drill the 1.5 inch hole in the cast manifold and weld the tube in place.

I have my own Craftsman 110 MIG welder with Flux core wire, but the Muffler shop has a professional Millematic unit that I usually pay to have someone go back over my
spotty welds. I have reviewed techniques of heating the manifold evenly and/or welding it cold. Should I use a heat gun to heat it up or would a torch do a better job? Does anybody have any good suggestions on how this should be done with MIG? I am looking for techniques, voltage settings, and anything that you guys can think of! Thanks!
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Old 07-26-2010, 12:24 PM
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Originally Posted by 3800SII View Post
I did an internet search, but I get different techniques, methods, and ideas. Anybody got real world examples?

The project is a 99 Pontiac Firebird V6 with a front mounted, twinscroll turbocharger. I have a cast iron exhaust manifold from a Pontiac Grand Prix 3.8 GTP that is being flipped around and used a turbo manifold for the driver's side. The passenger side was custom fabbed with 304 SS and Schedule 10 bends. I want to attach a WG bung made of thick stainless steel and hang the WG off the backside of each manifold and angle the exhaust straight down in order to vent to atmosphere. This will save alot of room and possibly reduce heat in the engine bay. The problem is that I have to drill the 1.5 inch hole in the cast manifold and weld the tube in place.

I have my own Craftsman 110 MIG welder with Flux core wire, but the Muffler shop has a professional Millematic unit that I usually pay to have someone go back over my
spotty welds. I have reviewed techniques of heating the manifold evenly and/or welding it cold. Should I use a heat gun to heat it up or would a torch do a better job? Does anybody have any good suggestions on how this should be done with MIG? I am looking for techniques, voltage settings, and anything that you guys can think of! Thanks!
Here is a thing I found. I am somewhat of a welding novice, but for cast iron, I think you want to heat it up in an oven.

How to Weld Cast Metal
unclet53 Member
By T G Hardee, eHow Member
Article Rating: (2 Ratings)

PRE-HEATING IS IMPORTANT!
PRE-HEATING IS IMPORTANT!
WELDGURU.COM

Welding cast iron can be very tricky. The proper procedures must be followed, or even more extensive damage can be done while welding this fickle material. These steps should guide you to a successful repair.
Difficulty: Challenging
Instructions
Things You'll Need:

* grinder
* stick welder
* drill and 1/8 bit
* oven (if available)
* fireproof blanket or dry sand
* wire brush
* heating torch

1.
Step 1

Clean the cast iron object to be welded with degreaser or appropriate cleaner. In the case of a crack to be welded, determine where the crack begins and ends, and drill a 1/8 hole at each end. Using a side grinder, or other tool, grind a "V" shape down the length of the crack, being careful not to go all the way through the metal.
2.
Step 2

Slowly pre-heat the entire cast iron object to about 500 degrees to help prevent further damage from the heat of welding. Determine the appropriate cast welding rods for the job, and weld on low heat, beginning at each end with short tacks. After this, weld in the same direction each time. If a lengthy crack, put short tacks along length to be welded. Complete job by adding short welds, approximately an inch or so at a time, allowing short cool-down periods between welds to keep heat to a minimum.
3.
Step 3

After welding is complete, a slow cool-down to ambient temperature is a must. Place item in a hot oven, and lower the temperature by about 50-60 degrees per hour until air temperature is reached. If no oven is available, cover item with dry sand or wrap in a fireproof blanket.

Tips & Warnings

*
The 1/8 holes helps stop crack from furthering due to heat stress.
*
If unsure about proper rods & size, refer to your welding supplier, giving information about thickness, item being welded, etc.
*
The "V" chamfer should be no more than about 40 degrees, equally ground on each side of crack.
*
To join two pieces of cast together, same procedure is advised.
*
A slow pre-heat and cool-down is very important to prevent cracking. The cool-down will be too rapid if left in open air.
*
If a pre-heat of the entire item is impossible, heat around the repair area as far as possible, tapering off heat slowly.
*
Before beginning, remove any bearings, seals or other items that could be damaged from heat.
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Old 07-26-2010, 10:28 PM
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I have a cheap arc welder too, but I have never had any success with using it. Thanks for the info! I am going to try this when the parts come in for the WG.
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Old 07-27-2010, 12:26 AM
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I have welded castings in powerplants. We would always preheat to 350*f minimum depending on the exact type of iron/steel. After the welding is finished we would have the piece stress relieved via heat.

SMAW (stick) was always our prefered method for castings. If you're going to use a mig get the appropriate flux cored wire and use a shielding gas. It is common to use dual shielding when welding on steam turbine equipment.

Go to your local welding supply store tell them what you have and take their recommendation. Ask for a good starting point for your equipment and have scrap pieces to practice on before beginning your work.

good luck.
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Old 07-27-2010, 04:49 PM
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Unfortunatly I don't have complete pictures, but this is a set of modified manifolds that I did to fit a 500ci caddy in a 66 lemans, it's a steel flange, welded to a cast elbow, welded to a cast manifold on this side, and on the other side the cast manifold was cut open on it's face and the steel flange was welded half to the cast manifold and half to a 1/4" thick steel piece that was heated with a torch and hammered to shape to seal the rest of the opening.

They were welded with flux core on a lincoln SP135 with no preheat, that's not really the important part, it's making sure that they cool slowly, I threw them in a bucket of kitty litter and covered them with welding gloves and some other stuff to get them to cool slow,

FWIW, car is a daily driver and has been running with those for almost 7 years with no problems.


Attached Thumbnails Mig weld steel on cast iron manifold?-exhaustmanifolds_04-06-26_11s.jpg  
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Old 07-27-2010, 05:16 PM
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this is flux welded using a lincoln 140hd 110v . no pre heating.

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Old 07-28-2010, 01:08 PM
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Originally Posted by Silverback View Post
Unfortunatly I don't have complete pictures, but this is a set of modified manifolds that I did to fit a 500ci caddy in a 66 lemans, it's a steel flange, welded to a cast elbow, welded to a cast manifold on this side, and on the other side the cast manifold was cut open on it's face and the steel flange was welded half to the cast manifold and half to a 1/4" thick steel piece that was heated with a torch and hammered to shape to seal the rest of the opening.

They were welded with flux core on a lincoln SP135 with no preheat, that's not really the important part, it's making sure that they cool slowly, I threw them in a bucket of kitty litter and covered them with welding gloves and some other stuff to get them to cool slow,

FWIW, car is a daily driver and has been running with those for almost 7 years with no problems.


Thank you so much!
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Old 07-28-2010, 02:03 PM
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I'm looking to do the same thing to a set of truck manifolds for a turbo setup on my trans am. I called my local fabricator and he said he couldn't do it?!?!?

We have a stick welder at our shop here. I was going to buy a MIG for general fabrication/tacking- then take the parts to be TIG welded so they look nice.
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Old 07-28-2010, 03:29 PM
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Originally Posted by White.Lightning View Post
I'm looking to do the same thing to a set of truck manifolds for a turbo setup on my trans am. I called my local fabricator and he said he couldn't do it?!?!?

We have a stick welder at our shop here. I was going to buy a MIG for general fabrication/tacking- then take the parts to be TIG welded so they look nice.
I will get my parts tomorrow and take them to the shop on Friday. I am going to try the pre-heat method and make small tacks on the manifold, clean off the spatter and work them again for a second pass. I really appreciate the idea of using kitty litter or sand to help keep the heat in and cool it slowly. I will post pics of the completed work on Friday when I get back.
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Old 07-28-2010, 05:30 PM
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i always set my welding machine as high as it will go when im joining to different kinds of steel/iron together. sure the weld it hotter than it needs to be but it gives me more penetration , i use flux core wire with 75/25 shielding gas on top of it.


i dont preheat either
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Old 07-28-2010, 05:47 PM
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I've welded bungs onto old Chevy manifolds with a stick
box. I think the manifolds may be more like nodular iron,
they drilled easy and welded fine. Whereas heads would
laugh at my HSS drill bits.
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Old 07-28-2010, 06:07 PM
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Old 07-28-2010, 10:03 PM
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Originally Posted by daryn c View Post
i always set my welding machine as high as it will go when im joining to different kinds of steel/iron together. sure the weld it hotter than it needs to be but it gives me more penetration , i use flux core wire with 75/25 shielding gas on top of it.


i dont preheat either
I have a flux core gasless wire in my welder, but I don't have exteral shielding gas. Could it work without the shielding gas? My settings don't go too high on the Craftsman unit, and I question the penetration. I might try a practice runs on some old Iron to see if it works..The shop has the shielding gas and carbon steel wire feed on their MIG unit. Regardless...that is totally amazing quality, and I appreciate you providing the pics.
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Old 07-28-2010, 11:18 PM
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All of the SMAW welding I did was without shielding gas. Stick welding is very effective and the most commong type of welding done in very demanding environments.TIG was often used for the root pass after a pipe sever and prep. I was surprised when i found that out. I worked for a company for about a year that did on site machining and welding for power plants. Steam chests we did entirely with stick in most cases.

I was 6g certified under our welding manager and my welds have been tested over 100 tons pullin and bending (welding to main stop valve seats to be pulled out with hydraulic rams). My welds were good enough for power plant steam lines carrying 3500ps1 1000*f steam.

Did you guys know there is wire feed TIG? I didn't til I worked in power plants. The wire feed TIG was used to rebuild material in steam valves to they can be machined. Operated by a pendant in the hands of a competent weldor. beautiful welds when done right. machines break easily though.

I can weld but I'm not a weldor. there is a difference...
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Old 08-01-2010, 10:07 PM
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Thanks for all the suggestions! The shop just took the Millermatic welder to the manifold and made a couple of slow passes. The hot welds stuck perfectly, and no cracking whatsoever. I let it cool in some oil dry and sand.
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Old 08-06-2010, 09:30 PM
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Originally Posted by Cheatin' Chad View Post
All of the SMAW welding I did was without shielding gas. Stick welding is very effective and the most commong type of welding done in very demanding environments.TIG was often used for the root pass after a pipe sever and prep. I was surprised when i found that out. I worked for a company for about a year that did on site machining and welding for power plants. Steam chests we did entirely with stick in most cases.

Did you guys know there is wire feed TIG? I didn't til I worked in power plants. The wire feed TIG was used to rebuild material in steam valves to they can be machined. Operated by a pendant in the hands of a competent weldor. beautiful welds when done right. machines break easily though.

I can weld but I'm not a weldor. there is a difference...

SMAW (shielded metal arc welding) creates its own shielding gas by burning the flux on the electrode. Are you referring to Flux core thats not dual shield?

As far as the self feeding TIG, I have seen it before and apparantly its a pricey torch. I much prefer welding by hand, although I have never personally used one.

To the OP I have welded cast iron before and just as everyone else said the cooling is the biggest part of getting a weld that will hold and not crack.

Did the welds work out for you? Have any pics of this setup?
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Old 08-07-2010, 01:43 AM
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i am a welder but have never done cast iron.......but we were taught in weld school to pre heat and use stick with special rods
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Old 08-07-2010, 09:04 AM
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I have actually used just a regular 70/18 rod many times to weld cast iron, preheat is not as important as it is to let it cool slowly. It is important though, because it brings the entire object being welded up to temperature evenly, vs just the area being welded. Witch in turn creates less stress from difference in temperature across the object. It should not be too much of a issue if you fallow the correct procedures. A bung is easier to weld in then it would be to fix a crack. If you do not preheat a crack in cast before welding it the heat from the puddle will cause the metal to expand very quickly, and cause the crack to expand. Hope this was helpful.
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Old 08-08-2010, 04:06 PM
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Originally Posted by NHRATRANSAM64 View Post
SMAW (shielded metal arc welding) creates its own shielding gas by burning the flux on the electrode. Are you referring to Flux core thats not dual shield?

As far as the self feeding TIG, I have seen it before and apparantly its a pricey torch. I much prefer welding by hand, although I have never personally used one.
There was some "stick" and "TIG" welding done bagged up with the tent filled with argon. I never did that and would consider that a dual shielded welding situation.

On the root passes on some piping the pipe was capped and filled with argon. I can't TIG for **** so I wasn't the guy doing that either. Stick and Wirefeed only. My TIG looks like someone with parkinsons did it.

The wirefeed TIG was used in deep holes usually and they need to be extremely consistent. I doubt many humans can weld from the bottom of an 8"id pipe 36" deep all the way to the top of it and maintain the consistency of the machine.The weld quality was amazing. Finicky to set-up, a few of the guys could make that thing work art. I'd just break the damn thing

Then we'd go back and machine to within +/-.0005 Real interesting work but the hours,traveling,and shitty co-workers got stale...
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