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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Steel hardening
Looking at the posts on metal hardening I was wondering what are the
dynamics of oil versus water hardening.What is happening to the metal using one or the other?I assume water brings down the temperature quicker but have no empirical knowledge on the subject. |
#2
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that's right, water quenches more violently - GWE
Time Traveler wrote: Looking at the posts on metal hardening I was wondering what are the dynamics of oil versus water hardening.What is happening to the metal using one or the other?I assume water brings down the temperature quicker but have no empirical knowledge on the subject. |
#4
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Water offers the most "severe" quench. It would normally extract the heat
from the steel the quickest. The metal will vaporize the water and form a steam layer. Heat transfer is not so fast through the steam layer. On the other hand the very act of transforming the water into steam means the water has to take in enormous amounts of energy to transform the water from liquid state to gaseous state (steam). Moving the part and recirculating the water aids in getting the best quench. With oil there is much less vapor formation of the oil. There might be a little bubbling seen but nowhere as violent as with water. Therefore the heat removal rate is slower. There is another quench in between these two, which is polymer quenchants. These offer a compromise. The choice for quench mdeia depends on the steel grade being quenched, the part geometry and some other factors like whether quenching is being done in an atmospheric controlled integral-quench furnace, for example. Mark "Time Traveler" wrote in message ... Looking at the posts on metal hardening I was wondering what are the dynamics of oil versus water hardening.What is happening to the metal using one or the other?I assume water brings down the temperature quicker but have no empirical knowledge on the subject. |
#5
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"Time Traveler" wrote in message
... Looking at the posts on metal hardening I was wondering what are the dynamics of oil versus water hardening.What is happening to the metal using one or the other?I assume water brings down the temperature quicker but have no empirical knowledge on the subject. As others have said, you're right about that, and, depending on the alloy, thickness, and temperature of the quenching bath, the water quench may well give you a little more hardness. In the case of plain-carbon steels, water will give you more hardness on all but the thinnest pieces. But slower-quenching alloys, especially those that collectively are called "oil hardening," may not harden any more with a water quench. In fact, if the piece is more than 1/4" thick or so, all that water will do is increase the risk that the piece will crack. Water may, however, result in a *deeper*, if not a harder, hardened zone in that case. As for what is happening to the metal, you'd do well to find a description online or in a book. It involves a couple of phase-changes in the steel. The phase changes are generally the same for carbon steel and common alloys, but it's better absorbed from a description written by experts who have had the time to re-write, and an editor. -- Ed Huntress |
#6
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Gentlemen,thanks for the advice.Will try both ways in the backyard over
the next few days. |
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