Maillemaker Posted February 23, 2011 Share Posted February 23, 2011 While I am relatively new to blacksmithing, I would like to think I have my feet under me as far as basic skills go. However, I don't know of any experienced smiths in my area, so I have to turn to books and this wonderful forum. In The Blacksmith's Craft: A Primer of Tools & Methods by Charles McRaven, he states that after running the colors in a forge (heat treating) you should not quench your tool/project. Apparently, quenching the tool could harden the tool again. My latest project was a punch drawn out from a piece of coil spring (5160-ish), so I know there's enough carbon to allow hardening. After completely hardening (heat to red, then quench) I stuck the blunt end in the forge, and slowly ran the colors until the business end was a light straw. Heeding Mr. McRaven's advise, I allowed the punch to air-cool, and by the time it had cooled, the tip was a honey-bronze. My question is; can I somehow cool my workpiece more quickly without jeopardizing the heat treatment process? Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted February 23, 2011 Share Posted February 23, 2011 Apparently, quenching the tool could harden the tool again. There is no documented process for hardening steel that involves heating to 400-600 and quenching. So it won't make it harder. In fact, when using body heat to do the draw it is often recommended to quench in order to "arrest the draw". Quote Link to comment Share on other sites More sharing options...
MattBower Posted February 23, 2011 Share Posted February 23, 2011 In order for steel to harden as a result of quenching, it has to be quenched from the austenitic phase. Iron doesn't begin to become austenitic until around 1400 F (or a little hotter or cooler, depending on the alloy). So no, quenching from a typical tempering temperature won't "re-harden" your steel. Tempering the steel and then allowing it to cool to room temperature can sometimes result in a gain in hardness, if the steel contained "retained austenite" -- that is, austenite that didn't kick over to martensite during the quench, as we would like it to. (Tempering can cause retained austenite to transform to martensite. That's why you can sometimes actually gain a little hardness after tempering.) I think that's one reason multiple tempering cycles are sometimes recommended. But AFAIK, retained austenite isn't likely to be a problem with most low alloy steels. (Don't quote me on that.) Quote Link to comment Share on other sites More sharing options...
Maillemaker Posted February 23, 2011 Author Share Posted February 23, 2011 *facepalm* I should have known that. It just so happens that I'm studying material processes, and I just finished the metals section. Great advise, and keep it coming! The more help I can get, the better! Quote Link to comment Share on other sites More sharing options...
pkrankow Posted February 23, 2011 Share Posted February 23, 2011 *facepalm* I should have known that. It just so happens that I'm studying material processes, and I just finished the metals section. Great advise, and keep it coming! The more help I can get, the better! Happens to the best of us, get too much jumbled together in the coconut and things you know suddenly don't make sense anymore. With some applications the quench to arrest (or prevent) tempering can shock the steel more than letting it air cool would. Some people rotate punches and drifts for this reason, instead of cooling in water or oil. Phil Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted February 24, 2011 Share Posted February 24, 2011 With some applications the quench to arrest (or prevent) tempering can shock the steel more than letting it air cool would. Some people rotate punches and drifts for this reason, instead of cooling in water or oil. Phil I've used punches made from carbon steel, S-series, H-series. Used them all day long punching 800 - 1000 holes a day. Punch a hole, cool the punch, punch a hole, cool the punch, hot, cold, hot, cold. Did this all day long, almost never had a problem. Just chasing ghosts worrying about it. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted February 24, 2011 Share Posted February 24, 2011 I've used punches made from carbon steel, S-series, H-series. Used them all day long punching 800 - 1000 holes a day. Punch a hole, cool the punch, punch a hole, cool the punch, hot, cold, hot, cold. Did this all day long, almost never had a problem. Just chasing ghosts worrying about it. I didn't say everybody. I don't worry about it either. No color then it is cooling. Phil Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted March 24, 2011 Share Posted March 24, 2011 I don't have McRaven's book, but perhaps he is talking about having a residual red heat on the striking end. Or perhaps, the reserve heat method where you're quenching about one half the hardening heat and allowing the reddish heat above the water line to chase color. If the bands of tempering colors run rapidly, you may still retain a red heat behind them. When that occurs, I do not quench the red heat, even though the correct temperature has reached the business end. Maillemaker said that he put the striking head in the fire to chase color. If a small portion of the end is in the fire, it may turn red before the tempering color is reached. Is this what's going on? If so, get a small tin can and fill with about one inch of water. You can quench the business end in the can of water at the correct temper while the hot end above is "normalizing" above the water line. http://www.turleyforge.com Granddaddy of Blacksmith Schools Quote Link to comment Share on other sites More sharing options...
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