<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: heat treating steel</title></head><body> <div>----- Original Message ----- From: "Carl Meyer" <cmpiano@comcast.net></div> <div>To: <pianotech@ptg.org></div> <div>Sent: Wednesday, January 05, 2005 6:08 PM</div> <div>Subject: heat treating steel</div> <div><br></div> <div><br></div> <blockquote type="cite" cite>Almost any alloy of steel can be checked on the net for the specs for annealing, hardening and tempering.</blockquote> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>My question is:  Is there an easy way to guess the approx temp of steel? Cherry red, or what?</blockquote> <div><br></div> <div>There are color charts published in various handbooks which give an approximate indication of color due to temperature</div> <div><br></div> <blockquote type="cite" cite>If it says quench with oil, what will happen if you use water?</blockquote> <div><br></div> <div>Oil quenching grades of alloy steel are designed to achieve an appropriate level hardness when being quenched from cherry red in oil, in which there will be a much less severe rate of cooling relative to water quenching. Oil quenching grades of steel are more expensive than straight carbon steels, through the addition of other alloying elements which improve the hardenability of the alloy. To quote from the "Marks Handbook" (fourth edition 1941);</div> <div><br></div> <div><font color="#0000FF">The oil-hardening steels, sometimes called non-deforming steels, have sufficient alloy content to be hardened on quenching in oil: distortion and cracking is therefore minimised. They usually contain up to 1.75 percent Manganese with small percentages of Chromium, molybdenum, vanadium, or tungsten and have the same general performance characteristics as plain carbon tool steels.</font></div> <div><br></div> <blockquote type="cite" cite>If it says quench with water, what will happen if you use oil?</blockquote> <div><br></div> <div>Water quenching steels are usually a straight alloy of carbon and iron. These alloys will not achieve an appropriate level of hardness if they are oil quenched. They require the faster cooling rate of water.</div> <div><br></div> <blockquote type="cite" cite>If you didn't heat it quite so hot and quenched it, would it be less hard and not so brittle?</blockquote> <div><br></div> <div>Indeed. But the idea of quenching is to attain maximum hardness, to be followed by the annealing process, in which the object is heated only to a temperature which allows the grain size to increase until the desired balance between hardness and toughness is achieved.</div> <div><br></div> <blockquote type="cite" cite>I wish I knew more about this, but I'm too old to go take a masters degree on it.</blockquote> <div><br></div> <div>Get hold of a good hand book. I have two which were published by the former Australian Steel supply Co. Eagle & Globe, "More hints on steel".</div> <div><br></div> <blockquote type="cite" cite>The instacoilers sold by Schaff have cracked because they were not tempered.</blockquote> <div><br></div> <div>Possibly.</div> <div><br></div> <div>At 1:38 AM -0700 10/1/05, Dave Nereson wrote:</div> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>   I had a blacksmith friend who helped me make a custom backcheck bender that actually fit around the bridle wire.  We used "tool steel," whatever that is, heated it up to red hot, I think, to anneal it (make it soft) in order to file, grind and shape the tool to how I wanted it.  Then to temper it, we re-heated it slowly, watching the subtle (VERY subtle) changes in the color of the metal and when it got to straw yellow, we quenched it, in water I think.  I forget the sequence of colors and it would take me a while to look it up.</blockquote> <div> </div> <div>Hi Dave,</div> <div><br></div> <div>A slow cooling process is the usual procedure once the desired annealing temperature has been reached. The heating and quenching part is quite easy. The harder bit is heating the object to an even-annealing-temperature before letting it cool slowly. A electric oven is better for the annealing stage than trying to heat the object with a naked flame and judging its temperature by eye.</div> <div><br></div> <div>Before annealing by eye, the object should be highly polished and heated against a good light source, so that the level of oxidation which reveals the annealing temperature can be seen.</div> <div><br></div> <div>Ron O.</div> <x-sigsep><pre>-- </pre></x-sigsep> <div><font face="Times New Roman" size="+1" color="#0000FF"><b>OVERS PIANOS - SYDNEY</b></font></div> <div><font color="#000000"><i>   </i></font><font color="#0000FF"><i>Grand Piano Manufacturers</i></font><font color="#000000"><br> _______________________</font></div> <div><font size="-2" color="#000000"><br> </font><font color="#000000">Web http://overspianos.com.au</font></div> <div><font color="#000000">mailto:ron@overspianos.com.au<br> _______________________</font></div> </body> </html>