mickyd555 wrote:Can anyone tell me what went wrong with this weld. It is the rear bracing on a highmount winch (gearbox end). It looks like it is going to be sufficient to do the job its intended to but is very ordinary looking. If i hit it with a grinder to tidy it up will it be ok?
Ok, 1st up. You've picked a pretty difficult casting to weld.
The high mount castings aren't the easiest of things to weld being a poor quality pressure casting. They usually have a fairly high Zinc content which is fine for its flow properties in casting but cr@p when it comes to welding.
Zinc has a lower melting point than Aluminium and will "outgas" during welding. You'll see it while welding with giant porosity holes forming as you are welding (TIG). These holes generally close over as it cools but you know for sure the weld is like an Aero chocolate bar underneath.
4043 or 4047 filler wire is the filler of choice.
The technique I use is for fairly high amps and using a start/stop style of welding.
Get a puddle started fast then add the filler and then stop and allow the weld pool to freeze, then move and repeat and keep on repeating till finished. All this is done pretty quickly, doing it this way allows you to add filler but being so quick to add filler and stop it helps prevent the Zinc from getting a chance to outgas.
It's still not going to be pretty but now you have a base metal that is prodominently filler wire and that will now allow you to put a capping run over the top of it being careful not to go too close to the margins of the weld and casting.
Regards Andrew.
We are Tig welders, gravity doesn't worry us.
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