4xdblack Posted May 17, 2017 Share Posted May 17, 2017 I've been searching for a while now but can't find any useful information. I understand the differences between the two steels, but how do I determine what type of steel I'm holding in my hand? I've got a lot of scrap metal down in my barn that I don't know what it belonged to or what it is used for, I'm pretty sure it's all steel, but I don't know how to tell if it's mild steel or high carbon steel, or something in between. Is there any trick to figuring this out or do I just have to find out the hard way? Quote Link to comment Share on other sites More sharing options...
JHCC Posted May 17, 2017 Share Posted May 17, 2017 Look up spark testing and break testing. Quote Link to comment Share on other sites More sharing options...
Jackdawg Posted May 17, 2017 Share Posted May 17, 2017 If you bought it, your wallet will be considerably lighter if it was high carbon steel For checking scrap, JHCC has mentioned the most used tests done on the steel itself, for exotic stuff, there are some extras - for stainless you can also add is it or isnt it magnetic (300 series is non magnetic and no carbon, 400 series is generally magnetic and has at least some carbon), what was it was used for - if it is obvious what its past life was that is a big hint an old axle or drive shaft, likely medium carbon steel, ( might have a few extras like a dash of moly and chrome in it), coil springs medium and a little higher carbon, flat springs medium carbon, old grader blades or similar cutting edges etc medium to high carbon Old tools can give it away as well, files will be high carbon (as long as they are not antiques), Cutting implements medium to high carbon depending on what they were used for, you can actually file test these to see if they are hardened as you find them (no need to run a heat treating cycle) - unless totally worn out (past a working surface to a backing metal) or been through a fire, a carbon steel tool should exhibit hardness Some old bed frames tend to be medium to high carbon steel (Those thin angle iron ones that held metal mesh and springs) If it is general RHS, Square, rod, angle iron scrap, it will generally be a mild steel. Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted May 17, 2017 Share Posted May 17, 2017 Spark tests are the only easy way to access whether it is Carbon or mild steel or wrought iron or cast iron.. Pretty much any of the ferrous types.. Problem is it doesn't give any hint to anything other than general carbon content and doesn't address whether it's air, water or oil hardening.. I will be making a mystery metal demystified video sometime this summer if my schedule permits and will help to narrow down this wide field of unknowns. Quote Link to comment Share on other sites More sharing options...
BIGGUNDOCTOR Posted May 17, 2017 Share Posted May 17, 2017 Carbon does not make it magnetic, the iron content does. Stainless steels will rust, and the original name was Stains-less because it rusted less than standard steel does. 300 series can be made magnetic, the pins in our rotary magnetic spinner were 304. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted May 17, 2017 Share Posted May 17, 2017 A handy help for the spark test is to start assembling a set of known steel test pieces and they you can test the unknown one against several known ones to determine which is closest. Quote Link to comment Share on other sites More sharing options...
Will W. Posted May 17, 2017 Share Posted May 17, 2017 It's been noted before (and I've seen it myself) that if you do a lot of grinding on high carbon steel with a particular wheel, pieces of that steel can become trapped in the wheel. Then when you go grind some mild, you'll see some branching sparks that make the metal *appear* to have a decent amount of carbon. Try to use new wheels or belts to identify scrap. Or, to circumvent such a problem, forge thin, quench, and break. Quote Link to comment Share on other sites More sharing options...
Mark Ling Posted May 18, 2017 Share Posted May 18, 2017 Since we are on the subject of using scrap steel, etc., be sure not to use any plated or galvanized steel, as it gives of dangerous and fatal fumes when heated. Littleblacksmith Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted May 18, 2017 Share Posted May 18, 2017 Not to mention that a lot of the old paint on steel was high lead---I'm past the point of worrying about reproductive toxins but a lot of y'all are not! Quote Link to comment Share on other sites More sharing options...
Chickpea Posted June 1, 2017 Share Posted June 1, 2017 Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted June 1, 2017 Share Posted June 1, 2017 You don't have this spark test chart in a PDF do you? Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted June 1, 2017 Share Posted June 1, 2017 I have it on this site. Have to scroll down to page 14. https://lists.man.lodz.pl/pipermail/odlew-pl/2010/04/att-0000/02._20Metallurgy_20Made_20Simple-_20Metal_20Identification_20Ready_20.pdf Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted June 1, 2017 Share Posted June 1, 2017 A very unscientific approach that might be helpful is to tap it with something hard and listen to the ring. High carbon steel rings at a higher pitch and with longer resonance than mild steel. Think of the sound you you'd hear when a drill bit hits the shop floor compared to the clank of a similarly sized nail. I realized one day while sweeping up my shop that I rarely lose a dropped drill bit but a whole lot of nails get away from me. I think the sound helps me to track where it went. Quote Link to comment Share on other sites More sharing options...
Will W. Posted June 2, 2017 Share Posted June 2, 2017 13 hours ago, rockstar.esq said: I think the sound helps me to track where it went. Drill bit echolocation? Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted June 6, 2017 Share Posted June 6, 2017 I promise to use only my powers for good! Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted June 6, 2017 Share Posted June 6, 2017 On 6/1/2017 at 5:04 PM, rockstar.esq said: A very unscientific approach that might be helpful is to tap it with something hard and listen to the ring. High carbon steel rings at a higher pitch and with longer resonance than mild steel. Think of the sound you you'd hear when a drill bit hits the shop floor compared to the clank of a similarly sized nail. I realized one day while sweeping up my shop that I rarely lose a dropped drill bit but a whole lot of nails get away from me. I think the sound helps me to track where it went. an annealed carbon steel or alloy bar will for the most part have the same resonance that can be picked up by humans as CR (Cold rolled).. That tink, tink sound becomes that dull thud sound.. Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted June 6, 2017 Share Posted June 6, 2017 JLP I agree about how the hardness of a carbon steel impacts it's resonance. It also stands to reason that different carbon contents, and alloy compositions would have different resonances. Even in it's softest annealed state, I have a bar of 1095 that is much harder than mild steel. With otherwise similar dimensions, the 1095 is clearly higher pitched than the mild. I've observed the same phenomenon with annealed automotive coil springs. Even when a file bites fairly easily on the high carbon, it's higher pitched than mild steel round stock. That being said, it's good to clarify that my approach relies on having some mild steel of similar section to compare the mystery metal to. Even then, it's FAR from conclusive. Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted June 6, 2017 Share Posted June 6, 2017 26 minutes ago, rockstar.esq said: JLP I agree about how the hardness of a carbon steel impacts it's resonance. It also stands to reason that different carbon contents, and alloy compositions would have different resonances. Even in it's softest annealed state, I have a bar of 1095 that is much harder than mild steel. With otherwise similar dimensions, the 1095 is clearly higher pitched than the mild. I've observed the same phenomenon with annealed automotive coil springs. Even when a file bites fairly easily on the high carbon, it's higher pitched than mild steel round stock. That being said, it's good to clarify that my approach relies on having some mild steel of similar section to compare the mystery metal to. Even then, it's FAR from conclusive. Cold rolled or hot rolled makes a big difference in mild steel and you didn't differentiate.... 1095 is getting to the top of the usable carbon content and offer's a marked difference between annealed 1045 and 1095 or HSS or S7 or H13.. I have H13 which sounds like a rock when struck.. thud, thud same with some 4140 bar annealed... There is a large range in between.. Again if we simply address vibration.. It would also depend of shape.. Different shapes have different tonal frequencies.. I've made mild steel swages that ring like a bell also mild steel chain.. Anyhow, while the test might work for you.. I believe you have enough experience to get a desired result.. I know how that is.. Spark test, heating test, hardening test, fracture test, temper test.. Gets you to a 90% ball park if not better.. I've only had a bad experience once with mystery metal when I made a punch out of old fashioned rock flat drills.. Turns out they are used as water hardened.. No temper at all.. So when used as a hot punch the work end just mushrooms up because of the heat even at a dark red barely visible in the shade of a hood. Yet can chip away at granite rock for hours on end with little damage compared to other steels.. Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted June 6, 2017 Share Posted June 6, 2017 JLP, You're quite correct that spark, heat, hardening, fracture, and temper testing are all much better indicators than sound. By the time I commented, all of those had been mentioned already in one form or another. I also started out by writing "A very unscientific approach..." My last reply ended by qualifying that it's far from conclusive. Quote Link to comment Share on other sites More sharing options...
Will W. Posted June 6, 2017 Share Posted June 6, 2017 5 hours ago, rockstar.esq said: I promise to use only my powers for good! Glad to hear it! Maybe you could help me find all my lost drill bits too? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 7, 2017 Share Posted June 7, 2017 As there are multiple factors affecting the "ring" it would be hard to use it to figure out only 1 of them. Quote Link to comment Share on other sites More sharing options...
John McPherson Posted June 7, 2017 Share Posted June 7, 2017 To inject a little scientific evidence to support the anecdotal evidence, may I present an industrial application of sound. Quality Control inspection and testing in industry. It is easy to differentiate a batch of properly heat treated bolts from a non quenched and tempered batch with Ultrasonic Testing (UT). Same metal chemistry, different crystallization pattern, gives a different 'bang' from the speed of the waves reflecting from internal surfaces. The machine can "hear" and measure the difference in a repeatable way. It can also detect microscopic cracking caused by bad processing. If a machine can detect a difference, a person who can pick out a family member's voice in a crowd can learn to use that innate discrimination ability if they chose to do so. You can tap a piece of pottery or a grindstone and listen for a thud or a ring, you can test an anvil for delamination with a ball bearing or a small hammer, why not other metals? Like a spark test, it requires some sort of mental and physical comparators. Is it perfect? No, but what is? But it can be useful, costs nothing, and requires no special tools to carry around. You already have that hat rack on the end of your neck. (Those of you that have necks.) Quote Link to comment Share on other sites More sharing options...
lanternnate Posted June 7, 2017 Share Posted June 7, 2017 I haven't mastered discerning sparks (or sound) so my cave man approach: take small piece, make small piece thin, make small piece hot, make small piece cold fast, hit small piece hard, did small piece break? Neither scientific or efficient, but effective. Quote Link to comment Share on other sites More sharing options...
aessinus Posted June 7, 2017 Share Posted June 7, 2017 On 5/17/2017 at 11:49 AM, ThomasPowers said: A handy help for the spark test is to start assembling a set of known steel test pieces and they you can test the unknown one against several known ones to determine which is closest. I still have my test kit from material science from,,, a while ago. Quote Link to comment Share on other sites More sharing options...
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