Depending on the material of the fork, you can possibly weld repair. I say this with great caution because expertise in welding and nondestructive testing is required to ensure a proper weld repair for this type of component.
29 CFR 1910.178(a)(2) requires that powered industrial trucks meet the design and construction requirements established in ANSI B56.1 - 1969.
ANSI B56.1 section 419.B then requires of the manufacturer: The factor of safety of forks shall be at least 3 to 1 based on the yield point of the material.
Section 702.B states: Only qualified and authorized personnel shall be permitted to maintain, repair, adjust, and inspect industrial trucks.
The above are code and safety standard requirements. If you were to ask a qualified individual what hazards they would warn of, and tips they would give, they would most likely answer as follows:
1) You first need to know what grade of steel the forks are constructed of, as well as the condition (strength, heat-treat condition) they are in via MTR inspection, nondestructive testing (e.g. - hardness, OES, chemical composition analysis, etc) and the like.
2) Next an assessment of the feasibility of welding this material in this condition needs to be performed. Provided it is possible to weld-repair this material, you'll need to weld using a fully qualified welding procedure, taking care to ensure that sufficient strength, ductility, and impact resistance will result.
3) Any weld-repair must be then inspected via appropriate NDE procedures to ensure a weld with sufficient integrity was had.
I get the feeling by your question that these recommendations will not be followed, in which case I would recommend simply purchasing replacement forks in lieu of incurring the risk of liability of injury or death of personnel operating or working in or around said forklift.
As others have said its a bad idea to weld on the forks of a fork lift, I would consider think what the insurance company might have to say about any weld repair you attempt.
Why does one repair instead of replace? To save money. Then begs the question, what is the cost of a human life in your region? Is it worth the risk? In my opinion, it is incredibly irresponsible to repair a fork. You cannot guarantee that any subsequent user/owner of the lift will be made aware that it was subject to an overload condition in its history, and now likely has a reduced capacity or service life because of that.
Bad ideas do not need a reference to counter their implementation. As long as people do not act beyond their level of expertise, things stay real.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
