Err....... I does quite often.
My own 6mm HD diff pan. And yes the axle is still straight. Most of the welding was done on the bench before welding to the axle case.
Held up well to the abuse I gave it last weekend.
Then again my set up isn't a typical hobbyist setup. Tis a sealey power mig 180. With full size argon mix bottle. And decent regulator. Run it off a dedicated 16amp socket for welding 6mm as it pops 13amp fuses for a pasttime at full chat.
Would still love a 3 phase welder at home mind. But this'll do for now. Welds 6mm no problem and has plenty of adjustment to be able to weld **** thin land rover bodywork.
So would highly recommend this one to anyone looking for a decent welder.