troy fairweather said:
Are you asking if EDM affects material properties. Typically a part will go to heat treat after EDM, at least that's what I've seen.
I called H&M Blacknitride yesterday. They do a lot of OEM work and can salt nitride a bunch of receivers, bolts etc. I sent them an email today asking about their process and how it might affect the hardness and toughness of a receiver or bolt.
After some digging I found the information from Ted at American Rifle Company.
https://www.americanrifle.com/shop/product/mausingfield-bolt-action-2
"An action needs to have a margin of safety to resist the dangerously high loads resulting from misuse. The margin of safety stems from both proper design and proper heat-treatment of the steel from which the action is made. Therefore, the Mausingfield action must never be subjected to temperatures above 400°F (204°C) for any reason, because doing so will significantly weaken it and compromise its safety margin. The Mausingfield must not be subjected to high-temperature surface treatments such as ferritic nitrocarburizing or salt-bath nitriding, because such treatments are conducted at temperatures ranging from 900-1200° F (480-650° C). These treatments are marketed under several trade names, including Nitrotec®, Tufftride®, Tenifer®, QPQ®, and Melonite®. While these finishes might be suitable for some firearms, they are not suitable for the Mausingfield and may not be suitable for other bolt actions either."
But interestingly, further down the page ...
"SURFACE TREATMENT
The Mausingfield is supplied with a salt bath nitride surface finish to harden and blacken its surfaces. The resulting finish effectively resists corrosion and reduces friction thus enhancing the smoothness of the action. The bolt head is coated with diamond-like carbon (DLC) surface finish. DLC is an extremely hard and wear-resistant layer on the exterior surfaces. This will reduce the friction between moving parts, thereby enhancing the smoothness of the action. DLC treated surfaces hold oil which enables them to resist corrosion reasonably well."