You will find that all fork lift forks are not the same (like men are as so we are so told by some women) from a metallurgical stand point but they do need to comply with certain design standards established by various standard organization in the US - ASME/ANSI, etc.
1. You will find the the carbon content of the steel is higher than others - typically forks from Japan have a lower carbon content than from the US.
2. How forks are manufactured & processed will vary from one company to another.
Don't really think you will have much luck finding info. on the web that will give you this info. as these are kinda' like "trade secrets" or "secrete recipes".
You best bet is to contact fork suppliers/manufacturers - in the US it is Cascade (aka Ken Har) Cascade bought Ken Har some time ago.