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
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
Second of two simultaneous responses ++
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.
- Goleta, California
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