Repairing forklift forks should be left to professionals. ANSI B.56.1 states:
6.2.8.2 Repair and Testing
(a) Repair. Only the manufacturer of the fork or an expert of equal competence shall decide if a fork may be repaired for continued use, and the repairs shall only be carried out by such parties. It is not recommended that surface cracks or wear be repaired by welding. When repairs necessitating resetting are required, the fork shall subsequently be subjected to an appropriate heat treatment, as necessary.
(b) Test Loading. A fork that has undergone repairs other than repair or replacement of the positioning lock and/or the marking, shall only be returned to service after being submitted to, and passing, the tests described in para. 7.27.3, except that the test load shall correspond to 2.5 times the rated capacity marked on the fork.
So, after all those considerations, it seems it is more cost effective to replace damaged forks than to take a chance.