|12-06-2012, 05:58 AM||#11|
Enjoying my last V8
Joined: Apr 2008
Location: Cypress, Tx
Its simple metallurgy not a” Black Art”?
Because 440C has the feature of secondary hardening, maximum hardness is achieved in a very narrow tempering temperature range. This temperature is dependent upon the actual chemistry of the material. It’s usually 875 df. The hardness increases with tempering up to 875 then hardness decreases quickly with tempering temperatures above 875 df. Stainless steels conduct heat more slowly than alloy steels so a practical way to “hit “the maximum hardness tempering temperature without overshooting is to pre-heat. Hold the parts at a slightly lower temperature for sufficient time and then set up the temperature to the desired temperature and hold for sufficient time. Pre-heating will also insure uniform tempering throughout the thick/thin sections of the part. 440C has very low ductility at its maximum hardness and ductility would be further reduced by cold operating temperatures.
96 XR650L, 96 Guzzi Sport, 07 BMW K1200GT,
86 Husky 400 XCE, 00 Husky Te 610 e, 1999 Husky TC610 SM, 2000 Cagiva GC; Google: TX7
fritzcoinc screwed with this post 12-06-2012 at 06:39 AM
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