Hello Boris,
I serve some shops in that business. You can't weld the cast iron cranks. The residual stresses will cause a catastrophic failure right next to the throw. The steel cranks are sub-arced. There are a couple of companies that produce welders designed for that purpose.
I also have some shops who arc spray the journals. This will be successful regardless of substrate composition. Block decks, bearing caps, bearing saddles, seal areas, fuel pump pads, and so forth, are also repaired using this thermal spray process.