Welding cast steel

[alan kemp]

I broke the steering bracket off my portal box at Manby. I managed to reweld it on site with mig and then welded the bolt to the repaired bracket followed by a large washer welded on for strength. The repair lasted well for the rest of the event and took some big hits without breaking again.

I would like to do the repair properly and modify both sides to something much stronger. My questions are:

What is the best (read strongest) steel I can weld to the existing portal box

What is the best method of welding such steel to the portal box

I plan to cut off the existing brackets and weld a much bigger, stronger bracket on which will sandwich a 20 mm rose joint between 2 plates.

Any of you super welders want to do the job for cash/cheque/beer tokens/thanks/invoice. I dont mind paying the going rate for a proper job. I can weld but have never welded cast steel properly...

A few peeps took photo's of the break, can someone send me one or post it on here, Ta

Alan

[simon_s]

Have a pic up in an hour or so Alan.

[simon_s]

Here you go alan.

Before:

After:

[Les Henson]

Don't you have to heat cast iron up before welding? I thought it was prone to cracking if you cold welded it?

Les.

[FridgeFreezer]

Mehtinks you need to speak to Jez if you haven't already. I'm not sure how he did it but I know it involved some fairly high levels of Fu.

[Guest noggy]

i believe you need to pre heat, and use a filler rod with a similar cooling rate to the cast, or it will probably crack, the mild steel will stretch/distort to the weld without cracking.

Jez will probably tell you the proper way, theres actually a lot of discussion all the time about how to weld cast correctly.

[Bull Bar Cowboy]

Cast steel can be readily welded. It usually has a low carbon content and can be treated as if it were a low carbon rolled steel. The main thing you have to be really careful about is distortion, but that is true of welding any ferrous metal. Welding is a standard industrial process for steel castings. If it is cast steel then treat it exactly the same as you would treat ordinary rolled steel ........... Your axle castings are most certainly cast steel as cast iron is lacking in ductility and would not survive very long.

Cast Iron is a whole different ball game, and as Les rightly says, cracking is an issue. Cast Iron is a iron carbon alloy and has a completely different structure to steel. There are also hundreds of different grades of cast Iron, some of which can be welded very successfully and some that will crack as soon as you look at them with a torch. This is certainly a specialist area and often the only way is trial and error to see the composition of the iron carbon alloy.

Ian

[alan kemp]

Cast steel can be readily welded. It usually has a low carbon content and can be treated as if it were a low carbon rolled steel. The main thing you have to be really careful about is distortion, but that is true of welding any ferrous metal. Welding is a standard industrial process for steel castings. If it is cast steel then treat it exactly the same as you would treat ordinary rolled steel ........... Your axle castings are most certainly cast steel as cast iron is lacking in ductility and would not survive very long.

Cast Iron is a whole different ball game, and as Les rightly says, cracking is an issue. Cast Iron is a iron carbon alloy and has a completely different structure to steel. There are also hundreds of different grades of cast Iron, some of which can be welded very successfully and some that will crack as soon as you look at them with a torch. This is certainly a specialist area and often the only way is trial and error to see the composition of the iron carbon alloy.

Ian

It is cast steel not iron, I was told I could not weld it with MIG but it did hold out for the rest of the day. The break was done on the first section same place as Tim rolled.

If cast steel can be treated exactly as normal rolled steel, I can beef the bracket up big time without any problem. Is MIG welding OK for cast steel, I must say there were some strange air bubbles on the odd bit, nothing to do with draughts etc. What is the best method of welding, I am set up for MIG, TIG and stick.

Thanks for the pics Simon.

[bill van snorkle]

Are we all certain that the portal box is cast steel ?It certainly won't be made from grey cast iron as used in engine blocks, gearbox castings etc. I'm more inclined to think it could be SG Nodular iron, the same stuff that LandRover outer swivel housings, Salisbury diff castings and TDI crankshafts are made from.

bill.

[Kim Horsevad]

(...)

What is the best (read strongest) steel I can weld to the existing portal box

What is the best method of welding such steel to the portal box

(...)

Alan

Since the portal box obviously is manufactured to cope with a great amount of shock it requires a material which is rather ductile and retains rather high tensile strength. This would at the same time mean that the amount of carbon in the casting is comparable to weldable steel.

Whether you weld it with stick or mig/mag should be of no specific importance. For more rare kinds of castings you have a greather selection of special rods with stick welding.

Your primary concern is to reduce heat stress during - and after - welding. Plan the welding to minimise heat stress. If you have the means of heating the area before welding, and after welding, and then allowing it to cool naturally, that would be the preferred way. As it - with considerable degree of certanity - is NOT ordinary (grey) cast iron, there should be no reason to heat it red hot - about 200- 300 degress should do fine.

If it is important to find out precise what kind of material the portal box is made of you would need to attack the box with an angle grinder in a place where a small amount of grinding dont produce any damage. Observe the sparks. Do the travel far? In straigt or curved lines? Do the stay near the grinding wheel? What colour does the sparks have?

Also observe the fracture - what is the crystalline structure? When attacked with a cold chisel, how does the material chip away?

I have attached to scans from an old book about metal fabrication. It should be possible to identify the material using these sheets.

[alan kemp]

Are we all certain that the portal box is cast steel ?It certainly won't be made from grey cast iron as used in engine blocks, gearbox castings etc. I'm more inclined to think it could be SG Nodular iron, the same stuff that LandRover outer swivel housings, Salisbury diff castings and TDI crankshafts are made from.

bill.

Actually, SG Nodular iron does ring a bell from years ago.

[dirtydiesel]

Treat it as conventional steel Alan.

The only additional prep i'd do is to give the entire area a good warming over first, i do this to cook out any carp thats soaked into the surface of the casting, otherwise you can get porousity from what otherwise looks to be clean steel.

Be very carfull about how much heat you put in to it, weld it in stages paying carful attention to your stop-starts.

[alan kemp]

Some excellent advice here guys, I will do the grinder test when I get a chance. Any body need a gas crucible, I have one for sale from a college.

[Tobias]

If you have the broken-off piece at hand and are prepared to send it to Sweden, I can have it tested for chemical composition and microstructure to give welding gurus something to work on.

Have access to all the right equipment ;-)

Tobias

[alan kemp]

If you have the broken-off piece at hand and are prepared to send it to Sweden, I can have it tested for chemical composition and microstructure to give welding gurus something to work on.

Have access to all the right equipment ;-)

Tobias

Thanks for your kind offer Tobias, I have the same offer from the UK.