Blacksmith Jim Posted May 7, 2007 Share Posted May 7, 2007 Howdy folks, I picked up a piece of metal that I think is likely 4140. Is there a good way that I can tell? Are there spark test photos that show 4140 being ground? I don't have any known pieces, so I can't really compare it against anything I have.. Quote Link to comment Share on other sites More sharing options...
Woody Posted May 7, 2007 Share Posted May 7, 2007 There used to be a guy on here that could tell the alloy of the steel by touch but he got banned. Other than that you buy unknown steel that's just what you got. I know there are those that say you can tell the alloy by a spark test but generally the best you can do with a spark test is to get an estimate of the carbon content. If spark testing were all that accurate steel mills wouldn't have analytical labs. If you can determine what the original application of the steel was, the junk yard steel list will give you an idea of what the alloy is. Other than that you can heat a piece of it to non magnetic, quench it in oil, check it with a file and see how hard it is. If the file cuts it readily, heat again and quench in water, then check with a file. If it's still easy to cut with a file you have low carbon steel. All of this was covered a while back and the information should be available if you search the archives. Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted May 7, 2007 Share Posted May 7, 2007 The short answer is "no". The best you could do is buy a certified piece of 4140 and do all the tests that Woody noted for comparison. Even then, it will be an educated guess. Quote Link to comment Share on other sites More sharing options...
Blacksmith Jim Posted May 7, 2007 Author Share Posted May 7, 2007 I picked it up at the conference I was just at. They were using a lot of 4140 for a bunch of the demos. A bunch of people had brought in steel for folks to use. I picked up a random piece and was forging it for a while, then went to bed. In hind sight it seemed harder to forge then normal, and looked more like a cold rolled or alloy. A few people noticed me forging it and asked if it was some of the 4140 that was around. I'm guessing it is, but I'll try quench and spark tests to check for carbon content. I guess I really don't care what kind of steel it is. If it has high carbon I'll just plan on making tools out of it. Quote Link to comment Share on other sites More sharing options...
evfreek Posted May 7, 2007 Share Posted May 7, 2007 Hi Regional Chaos. Eugene, OR? I met a fellow at the California Blacksmith Association Spring Conference from Eugene named Conrad. Know him? Anyway, if you are talking about those 3/4" rods in the buckets that were being passed out for the toolmaking workshop, I don't think they are 4140. If this is what you have, I can elaborate. Also, take a look at my gallery photos. I just posted a photo of sparks from 4140 prehard drop and one of the pieces of steel I mentioned above. Because of a poor quality picture, it is hard to get much out of them. Also, it is hard to tell the difference between the two. But it is clear that neither of them is S-7 or mild steel :rolleyes: Quote Link to comment Share on other sites More sharing options...
Blacksmith Jim Posted May 7, 2007 Author Share Posted May 7, 2007 evfreek, I've met Conrad at a few different events we have around here. One being the Oregon Country Fair. However I didn't go to the CBA conference. I went to the NWBA one up in Enumclaw, WA this last weekend. It was a lot of fun! Quote Link to comment Share on other sites More sharing options...
evfreek Posted May 7, 2007 Share Posted May 7, 2007 OK, then if it was a different conference, it may be different stuff. For photos, check out my gallery:http://www.iforgeiron.com/gallery/showgallery.php/ppuser/716/cat/500 It is easy to tell the 41xx apart from the other steels, and if you know what to look for, you can tell it apart from plain carbon steel. There is a paper on the WWW where a bunch of researchers collected some folks off the street and offered them a few bucks for each right answer. The test subjects made something like 97% correct guesses. But, there is a Japanese paper detailing the experiences of trying to train an expert system. The computer was awful. The 4140 photo is poor in quality, so it will not help you tell the difference between that and 4130. But it is still more realistic than BP0020. ;) Quote Link to comment Share on other sites More sharing options...
Glenn Posted May 8, 2007 Share Posted May 8, 2007 There used to be a guy on here that could tell the alloy of the steel by touch but he got banned. Just to clear the air, the fellow being referred to here was not banned for his abilities, or his remarks, or his beliefs. He was banned after the third use language that was not appropriate for a family forum. Site Admin Quote Link to comment Share on other sites More sharing options...
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