3lbhammer Posted May 31, 2011 Share Posted May 31, 2011 I have been making a knife from a rasp. I quenched in oil after heating to a bright cherry red (orange to me ) it did not get as hard as I expected. I did a test with another file in water and it came out very brittle. What should I have expected from the oil quench. I used liquid vegetable oil. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted May 31, 2011 Share Posted May 31, 2011 what metal was the file made from? high carbon or case hardened? what happened to that first file after you tried water did it harden then? Quote Link to comment Share on other sites More sharing options...
3lbhammer Posted May 31, 2011 Author Share Posted May 31, 2011 Idid not quench the knife I have been working on in water for fear of ruining it it is from a auto body rasp. After oil quench I could scratch the knife with a file. I believe it is high carbon steel Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted May 31, 2011 Share Posted May 31, 2011 Some files can be made of different materials and treated differently. It is not uncommon now to find files that have been made from lower carbon steel and case hardened on the teeth so they will cut. The only way a low tech person like me can figure out whether I want to use the file or not is to run some tests..on the same file you wish to use for a blade. Heat to non magnetic and quench in oil, see if a file will remove material from it or if the file skates off like it is glass hard. That is wot you want for a blade. Then you have to temper it so it is not brittle. If the oil does not harden the blade try again at non magnetec and quench in water. Same as before it should be hard. if not throw it in scrap pile and find andother file and start over. If you are an advanced enough smith to be doing blades then spend quite a bit of time on this site researching heat treating and wot it does and how to get it done. Good files are good. Other sources are springs from cars, trucks or go to place that makes leaf springs and ask for remnants or drops. They will tell you wot steel they are and likely how to heat treat that steel. There is a ton of info on this site. Not many folks likely to write lengthy answers for you as the data has been posted quite a few times. But if you do your homework and shop work and then get stuck post on here and someone will likley have an answer or thirteen different ones. Quote Link to comment Share on other sites More sharing options...
3lbhammer Posted May 31, 2011 Author Share Posted May 31, 2011 Rich, I have done a number of blades over the years of spring and of file material and never had one fail to get hard. I will try the same blade next in "brine" If it does not harden even in water Ill start over with another piece of steel . Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted May 31, 2011 Share Posted May 31, 2011 For unknown steel I try oil *first* and only with trepidation move on to brine or water if it didn't harden enough with oil. It is not unknown for a blade to be too soft after an oil quench yet break apart in a water one. (especially with a lot of stress risers like that file blade has. Quote Link to comment Share on other sites More sharing options...
3lbhammer Posted May 31, 2011 Author Share Posted May 31, 2011 Thanks for all the replies it may be adequately hard for general use without more heating just draw the temper. I have a piece of that file I will test it with a water quench and see what happens. If it becomes brittle I will leave well enough alone with the blade. What about cooling the oil as low as I can. I thought of setting the bucket of vegetable oil (a clean new one gal paint can) in a five gal bucket and surround it with ice. Let the quenching oil get as cold as I can make it. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted May 31, 2011 Share Posted May 31, 2011 The temp of the oil is important enough for me to test my oil each and every time with a thermometer, I use the oil at between 110 and 120f. In addition to wot I suggested above about research on blades, there is a lot wrritten on here about temps of oil as a quenchant. In addition to that research start a shop book and record each and every blade you heat treat. Notes about source of steel, wot temp you quenched at and what did you dip it in. Then add how it hardened and the steps you used in tempering. Then finish the blade and make notes of how it takes and holds an edge, how it performs. How it did with a bend test, and if you want an additional test use the brass rod on the edge and record that. This makes wot seems easy almost like work. But you likely already know that. It is the way to enhance your skills and provide background material for you to work with to make sure you can repeat each and every blade you like and more importantly it will help you not repeat things that did not work out at all. I hope you did not take my first answer in any way other than how I gave it to you: I can only respond to wot you posted. That gives me no idea of your history, abilities or equipment. Folks of all levels in all of the above pose questions in here. From folks that try and forge a blade on concrete with a claw hammer to those that I can only hope to be as talented and able to make wot they do. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted May 31, 2011 Share Posted May 31, 2011 .... I thought of setting the bucket of vegetable oil (a clean new one gal paint can) in a five gal bucket and surround it with ice. Let the quenching oil get as cold as I can make it. read about HT before asking this again. cold oil wont quench well. Quote Link to comment Share on other sites More sharing options...
3lbhammer Posted May 31, 2011 Author Share Posted May 31, 2011 Rich, I did not take your comments as negative or critical in any way. I never had this happen before. I do have a couple of knife blades that look like stain glass pattern after water quench or maybe varicose veins is a better description. I am truly an a amateur am a hobby smith. I will certainly do the record keeping. Quote Link to comment Share on other sites More sharing options...
son_of_bluegrass Posted May 31, 2011 Share Posted May 31, 2011 There are a number of possibilities as to why your blade didn't harden. As mentioned there are case-hardened low carbon files out there. You may be able to tell the difference by spark testing. Or the oil may not have been warm enough, oil works faster at warm temperatures. I try for around 130 F. You may have taken a bit too long to get the blade cool. Suitable files are often similar to 1095 and you have something under 1 second to get from the forge at 1500 F or so to below 900 F or so. A moments hesitation equals a soft blade. Or you may not have had the steel hot enough. How did you determine critical? Magnet? By eye? Or the forge gods may be messing with you. ron Quote Link to comment Share on other sites More sharing options...
3lbhammer Posted May 31, 2011 Author Share Posted May 31, 2011 The oil was the same temp as the air near 100 atmospheric temp in our are yesterday. I did test my visual Of orange color with an old scrap file cooled in water it became ver brittle, therefore I believe my forging temp was adequate. It all brings me back to the steel. I will do a couple of test and report. The case hardening of a file is new to me. Well I got a $1.00 piece of steel and maybe a $1.00 knife out of it. Quote Link to comment Share on other sites More sharing options...
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