So, with all the reminders of safety for chrome plating and how toxic it is, I began to wonder why it is that stainless steel (often containing chromium) is safe(or at least it seems to be safe) to forge? I understand that the vaporization of chrome or other ingestion methods is highly toxic, I just don't understand why that same element in an alloy wouldn't be toxic when heated to forging temps.

I can not tell you if SS is really 100% safe to forge, but there is a clear difference with chrome plating. Plating is pure chrome and Nickel laying on top of steel with a precarious hold on it. Once the steel expands in the forge the plating comes off and burns, giving up pure chrome. 304 SS for example has 18% chromium but that is not released when you heat it up, although some most certainly is. The question is how much and I don't know that. 

Lately there has been calls to say that SS is also unsafe to cook with. (?)

Any forging or even forge welding of steel, mild or stainless, is a solid state process. Temps rarely rise above 2500F for any length of time. That is plenty hot enough to burn off paints, oils, zinc, lead, or other low temp metals on the surface, so that you have a chance to breathe the fumes.

Chrome and nickel plating on tools are often done over a "buttering" layer of copper, which will boil off, taking the plating layer above with it.

Arc and plasma cutting/welding temps range from 10,000F to 40,000F, plenty hot enough to vaporize metal into reactive ions. 

Big difference when stuff is "tied down" too.  Sodium and Chlorine are *NASTY* stuff when running free; but yoke them together and I commonly ingest NaCl with my food...

Thanks guys. I think I am getting the general picture. So it may not be 100% safe, no matter the forging, and thus we use good ventilation in our shops. It also seems like the metals in stainless steel, because they are bonded differently than a plating, are not nearly as toxic when forged. Did i get the general picture? Sorry about the question, but since I had seen so many reminders about the dangers of chrome plating I just had an insatiable curiosity as to why SS doesn't seem to be very dangerous, at least as far as toxic fumes go.

Can I forge this, and forge weld the gear ? 

It would be helpfull if you added a location to your profile as then we would know if we have a potential language difficulty, I'm assuming you are from Russia and if so your English seems to be very good.

I don't now what the material is but I suspect due to the surface pitting it may be chrome plated and if so it is not advised to heat to welding/forging temps.

Hope that helps.