harry_r Posted March 31, 2015 Share Posted March 31, 2015 (edited) Hey all, my sister was in town and I found the motivation to fire up the coal forge to try and make some quick blades out of old files. First, the setting: take to non-magnetic (brick forge with charcoal), Oil quench, oven temper at 400 for 1.5Hrs. One had a slight warp. We wrapped the blade in damp towel and gently heated the area with a torch to ease thing, and then applied a little force. Snap. The grain looked like a normal file. Very tight/powder. The question: This seemed a temper failure, and as the blade was trash anyway I decided to test by reheating with the torch. Each time I was able to snap the blade with very little hammer force. Towards the end I heated the remaining piece to dull red (it was noon/bright but held the torch for long time), and it still snapped rather then bend. I could see grain size differences in the various parts (have a pic), but what confuses me is why it remained so brittle. After force heat I confirmed a file would bite, yet still brittle. Why did the temper, even extreme to the point of allowing file to bite, not work? I might think heat treat went wrong, for example over temp, but the first snap had very small/uniform grain so I doubt this hypothesis. Mystery metal? These were old files I got from my father's estate. I believe US made and no newer than 1980s vintage. Just the nature of a file based knife? If so, who wants one...... Thanks in advance for any thoughts. Regards Edit to add best pic I have of the grain at first snap. Edited March 31, 2015 by harry_r Link to comment Share on other sites More sharing options...
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