Hardening steel . . .
s.mackay@worldnet.att.net
>I remember this was a topic awhile back and I was bugging Dad about it. This was the Tool & Die Makers "short answer" ! Sheesh !
Tool steels, and their are many, require their own heating up temperatures and cooling down processes to harden them and have them hold up under terrible stress but not chip or break, all this in the field of metallurgy and it's a huge broad field to get into.Some steels I'm familiar with: 01 heat to 1500 degrees and put in an oil path until cool : A2 heat to 1700 degrees and set it out to air cool :S7 heat to 1800 degrees and set it out to air cool : 1040 heat to 1700 degrees and put in water bath.
The end mills I don't know but you get the idea, heat the tool steel machined shaped blank and put in a salt bath probably salt and water or salt and oil till cool. At this point all these steels are hard and brittle so if you would put them to work cutting metal, forming metal or putting it under heavy stress or torque they will surely break like glass.So now they have to go through a drawing back process. Reheat the metal pieces back up to a given lower temperature and put them in another bath or air cool depending on the particular steel. This process keeps the steel strong and hard but most importantly not brittle like glass to guard against breakage. After the end mill blanks have gone through this they are finish ground for sharpening and sold as a finished product.
Seems like I' v given you an awful long answer for a short question.