What exactly happens during the process? and what is the history on this practice?

Keep in mind that I am Koko the Sales Gorilla.

Crystalline structure becomes redefined from amorphous states to ordered states. This increases hardness.

Now, let's pretend the Internet is a good place to find such information...

Best site I have found is this PDF. It's from Honeywell - they actually know what they are talking about!

I know I can google, but it is nice to get "real" advice and how it pertains to weapons grade metals here on ARFcom....

Short answer, the molecules stop pushing and pulling each other in random directions and all stand at attention in rows like they were at morning roll call. Think of how the crystaline structure of  a diamond is, it's the same concept.

Dave

Quoted: Short answer, the molecules stop pushing and pulling each other in random directions and all stand at attention in rows like they were at morning roll call. Think of how the crystaline structure of  a diamond is, it's the same concept. Dave

I see

Quoted: I know I can google, but it is nice to get "real" advice and how it pertains to weapons grade metals here on ARFcom....

Yes, its always wise to trust some random guy on the internet vs pertinent results Google may give you

are you looking for general information or do you have a specific steel you need to work with?

Quoted: are you looking for general information or do you have a specific steel you need to work with?

Looking to buy a HK registered sear (price range of $10,000) and wanted to know about "metalurgy" pertaining to extending the life of such a piece of "precious" metal.   Don't want it to break now....

I wouldn't advise it.

Quoted: Quoted: are you looking for general information or do you have a specific steel you need to work with? Looking to buy a HK registered sear (price range of $10,000) and wanted to know about "metalurgy" pertaining to extending the life of such a piece of "precious" metal.   Don't want it to break now....

Keep it lubricated.  That's about all you can do.

Once it has been processed by the manufacturer the chances of you ruining it by trying to alter it are almost a sure thing.  Machined parts with holes, corners, voids, etc machined into them are very hard to heattreat properly due to the irregular surfaces and cooling characteristics of varying thicknesses.

To answer your question on heat treating, on ferrous metals several things come into play as to the finished characteristics of the item. Basically, the amount of carbon content limits the hardness potential and how much carbon is trapped in a finer grain structure in the moment between solid solution and quench temp determines the hardness, toughness, maleability, machineability, etc.

There is an infinite amount of variables but that is the very basic scoop.