tig ?

[Rambozo]

Another real common application of brazing is the buildup of broken cast iron parts that will need to be machined afterwards. You can fix some huge damage that way and the finished part will behave much like the original casting as there is little to no embrittlement at brazing temperatures. You do have to preheat the part and allow to cool slowly, but after you can machine the bronze and cast iron back to finished size and there is no hardened area near the repair line, like there is when welded. You can typically replace any features like threads, holes, and bearing bores, that may have been damaged. It's done all the time to fix spun bearings in cast iron parts. Bore out the damage, braze it up, then re-bore for the original bearing size.

[zoama]

Another real common application of brazing is the buildup of broken cast iron parts that will need to be machined afterwards. You can fix some huge damage that way and the finished part will behave much like the original casting as there is little to no embrittlement at brazing temperatures. You do have to preheat the part and allow to cool slowly, but after you can machine the bronze and cast iron back to finished size and there is no hardened area near the repair line, like there is when welded. You can typically replace any features like threads, holes, and bearing bores, that may have been damaged. It's done all the time to fix spun bearings in cast iron parts. Bore out the damage, braze it up, then re-bore for the original bearing size.

Could you replace a broken stud boss on a cast iron head with brazing and would it last ?

[Rambozo]

Could you replace a broken stud boss on a cast iron head with brazing and would it last ?

I've done it several times. It is possibly not quite as strong as the original cast boss, but way stronger than any other type of weld repair. Sometime you can add a gusset or build up the size of the boss to compensate, too. The good thing about bronze is the it is more malleable so it can take the vibration without cracking. Usually I use oxy-fuel for that, but I have TIG brazed up a front wheel hub to repair a spun bearing for a friend, since it was an after hours project. The brake job from Hell!

Keith Fenner at Turn Wright Machine has some extreme examples of brazing repairs on YouTube.