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Leaf spring: Help Identifying Steel?

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I know using mystery steels is generally frowned upon, but I have this leaf spring, and I might as well make use of it. I know it's either 1095 or 5160, but how do I identify which one, so I can heat treat it properly? I have done a few tests, with inconclusive results. Here's what I've done:


I heated up and quenched pieces of the steel in water and oil, hoping to see a difference in hardness and toughness. I quenched one in hot tap water, and one in room temperature canola oil.

The one quenched in water hardened up well, and skated a file, but it was brittle and broke when hit with a hammer.

The one quenched in oil failed to harden up properly and would not skate a file. I could easily scratch it with the water quenched piece. However, it was very tough and took a lot of force to break it with the hammer, even with my poorly done normalizing.


I don't really know what to think of this. I forgot to heat up my oil, but I figured 5160 should harden in the room temperature oil anyways.


Then I took it to a scrap metal place to use their XRF gun on it. The results were weird, and I have no idea how to interpret them, or if they're even accurate.

Here they are:

element: PPM

Balance: 16.9

Mn: 0.63

Fe: 73.19

Ni: 1.2

Cu: 1.53

Zn: 4.99

As: 0.32

Ag: 0.44

Pb: 0.43

The column header stated that the measurements are in ppm, but that seems wrong. I would've expected there would be a little more than 73.19 ppm Iron! However, if they're in percentages, it seems wrong too. for example 5% zinc can't be right. I would've also expected more than 73% iron. I'm so confused by these results that I'm thinking of just disregarding them completely. Is it possible that the rust on the surface was measured, instead of the steel?

Any help would be appreciated.

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It could be a number of other alloys as well. 1084, 1075, 9260, 8670, and so on.  There's no rule that springs have to be a particular alloy, only that they be able to act like a spring.  What did it come off of?  


Now then, based on your experiments, it's not 5160 since it didn't harden in oil and since it didn't crack in water. It's also perfectly normal for hardened steel to shatter like glass if you haven't tempered it after hardening.  It's probably a 10XX series steel, but we can't rule out 9260.


Finally, scrapyard XRF analysis is pretty useless for what we do.  Unless the unit is specifically calibrated for steel it'll give you gibberish, and on top of that they can't detect light elements like carbon.  They're really only for the scrap guy to be able to tell if something is steel or aluminum or copper.

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To add on to Alan's great response...


The surface of the material definitely should be free of rust before testing.  They are ever so slightly better than Alan is saying though (usually I'm the one saying that they are pretty worthless!), in that it should also be able to help sort between major alloy groups.  For example, between 304 and 316, it should pick up the Mo difference.  And it should get close enough to tell if something is mild steel vs 41XX or 43XX.  

I definitely would recommend ignoring all hand-held XRF readings for anything remotely important.  They are best used as a means to see if you should do further testing or not, typically via OES.  

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Thanks for the help everyone. How should I go about quenching it? It didn't harden properly in cold oil, but it might've done in a hot oil. I don't have any parks 50, so water is the other option. The piece I tested was quite small, maybe 2 cm by 3 cm, so it might not be a reliable indicator of how a bigger blade would behave.

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Warm oil might do it, try and see.  Size of the sample isn't that important, except for thickness.  Thin stuff will tend to harden faster than thicker stuff.  I saw you use metric, so I checked your IP address for location. You may well have EN43/9260, one of my favorite steels for big blades. It's extremely tough, but easy to forge.  It works fine in water, but warm oil is safer.  

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Honestly I had cases like this. Wont harden in oil, cracks in water......   The coil springs are limited to far les number of alloyes being more stressed and therefore safer bet in what they are supposed to be made from.

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Thanks so much everyone, you've helped me hugely. I've forged a small knife out of the spring steel, and I'll let you guys know if it goes well.

I'm told that 5160 is slightly tougher while 1095 has slightly better edge retention, but how does 9260 compare to those? I haven't found very much good information on how hard 9260 can be made, only that it is very tough and flexible. Also, is the heat treatment the same as 5160? I haven't been able to find much about that either.

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9260 (if that's what it is, what kind of vehicle did it come from?) is basically analogous to 5160, except with silicon instead of chromium.  It gets as hard, but it is tougher.  And yes, the HT is the same as 5160, which is why they are used interchangeably by spring shops.    

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