stainless to mild steel

[brendan h]

im making up some shock mounts for my 4wd but i have only got stainless. ive already made them up and ready to welded on. the moutns are 304 stainless because it was all i had onhand. question is for welding them on. will be welded inposition (vertical)
i was thinking of doing a mild steel 4012 2.5mm for the first pass vertical down. then using a 2.5 308 electrode going vertical up.
diff is 3mm thick and the mounts are 4mm. corrosion resistance isnt a problem because ill be spraying it with a cold gal coat then painting it black anyway. just needs to be strong

maybe even tiging it. time isnt an issue and gas isnt either.

 

[Hitch]

Ideally you would be using a 309ss electrode, they are designed for stainless onto mild steel material. I notice you say weld to the diff.... I assume that's a nice lump of cast? stainless to cast could be a little trickier, theres been a few threads regarding that recently. do a quick search for now...

 

[brendan h]

no the diff is not cast. its mild steel

 

[Paul.]

As Hitch says, generally for Austinetic stainless to mild steel a 309 stainless would be used, but you also have to consider the application, In a load bearing and alternating load joint such as a suspension mount, you could have cracking caused by weld fatigue, this will usually show on the HAZ, intergranular corrosion could also be a issue, obviously we don't know the stresses and joint design involved and it could well be that you'll be fine, but personally I'd have made them out of steel plate.

 

[brendan h]

its on a suzuki sierra. so there not much weight on it. the car it self weighs 1100kg

basic desighn on of it

 

[Paul.]

Could you make a bracket that wraps all round the axle casing, then you could just put 4 short welds around it, that would also reduce the distortion and resultant stress that is likely by welding on one side of the casing.

 

[brendan h]

its not posible.
but i found some steel its 10mm bigger (50x50x5) problem is now ive already got the stainless steel bolts. there shouldnt be a problem welding the bolt to the steel just to hold it in place

just made them up then and being 10mm wider is going to make a big difference. i now need to weigh up if the stainless ones are going to be strong enough or stick with the steel ones?
what are the odds of the stainless one cracking/braking off? i thinking of putting a square bit of plate onto the top and bottom of the diff and welding it to the mount making it stronger again
BLUE is where it will be welded ontop of the diff