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-----Hardening 440 stainless
I'm in the process of making a center punch out of 440 stainless but, I'm not sure how to harden this metal, can I get it cherry red and quench it in oil or water, please help!
Gordon Mooney- Billerica, Massachusetts
2002
First of two simultanneous responses
I think that there are better grades of SS for use as a center punch. As a faint memory serves me, you need to go hotter than a bright cherry which would be a lighter color. It will scale quite a bit also. They make special ss foil baggies and sheets for wrapping SS to keep the O2 off of it and thus a significant reduction in scale. Oil is better than water.
James Watts- Navarre, Florida
2002
Second of two simultaneous responses
Suggest
1) you download MIL-H-6875H, HEAT TREATMENT OF STEEL at http://assist2.daps.dla.mil/quicksearch/ A brief synopsis: 440C shall be hardened by austenizing (1900-1950 F)*, quenching (in oil, air, or aqueous polymer) and tempering (at 325 to 450 F, dependent on Rockwell Hardness). *the heating medium shall be so controlled as not to produce excessive decarburization. Of course, it shall also not produce carburization or nitriding.
2) find a qualified heat treater. Proper tempering is an essential safety consideration for items such as chisels.
Ken Vlach [deceased]- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2002
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