Steel analysis

Phil Dwyer

Phil Dwyer

Joined
Feb 28, 2006
Messages
3,494
Hi Friends,

You guys are probably fed up to your ears with steel analysis questions, but I'm wondering if you'll tolerate it for another go? I was given four big leaf springs by a mechanic next to our school. He got them for me from a friend of a friend of his. Each one must weigh near 75 pounds. It took two high schoolers just about all they had to move each one. Anyway, it's a lot of steel. Unfortunately I didn't get to meet or talk with the guy who started the pallet moving my way. (It was quite an adventure hopscotching this stuff across Honolulu.)

Soooo, my question. I not only want to get a alloy composition analysis, but a structural one as well. Does such a thing exist? It'd be great to know if this stuff is riddled with micro cracks before I go too far with it. Matt Doyle said he could get the composition specs for me, but no structural integrity info.

Anyone have any suggestions?

Thanks, Phil

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Personally, I think the microcrack thing is completely mythical and was started by somebody that quenched a spring in water. Yep, it would be full of micro cracks.

First thing I would do if I were worried about stress cracks is take a 1" wide chunk of it and put it in a BIG vice, then take a BIG hammer and wail on it until it breaks or bends to a 90. If it breaks really easy inspect it for evidence of cracking (partially rusted or discolored where it broke). If you get it to break I'm sure you'll be pleased with the grain; it should be silky smooth. That's your structural analysis.

Pound out a few thin blades and HT it like 5160 and test them in various ways to failure.

Send a sample to a lab for analysis if you like.
 
I agree with 69. If you plan on forging it the structure will be rearranged anyway. Microcracking is a problem with bridge parts and airplane wings, but not forged knives. Just an analysys should be all you need.
Stacy
 
There are several ways you could look for cracks (not micro) yourself. One is to get some dye penatrant. You clean the steel with say a flapper disk on a hand held grinder, wipe with a solvent then spray on the red penatrant then a white agent, The cracks will show as red lines in the white field. You can also use a finer set of agents that need a black light to make the cracks show better. The stuff is fairly cheap and easy to use. http://en.wikipedia.org/wiki/Dye_penetrant_inspection

Here is a place I found with google. http://www.drillspot.com/products/283771/magnaflux_itw_sk-416_dye_penetrant_kit. I could ask around at work for a supplier because it is used in my industry to check certain welds and pieces that have been stressed somehow.

The other is to use an small electromagnet, spray on some fine steel particials and the particals will line up on any cracks.

But, almost every broken leaf spring I have seen was broke near the center clamp and really broke. I also believe once they start cracking they break shortly thereafter. Looks to me like you probably got a pile of good steel. Enough to check out and experiment with and then have a pile of known steel. I have though of looking for exactly what you have to obtain a good supply of 5160.
 
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Now that's enough steel to make experimenting with it worthwhile.... I really have nothing else to add to this conversation. :p
 
Thanks for the input guys. I'm looking into the dye penetrant. I found a number of Magnaflux items on eBay.

I also thought to read up a bit on leaf spring failure for more background info. This link has a pretty good synopsis, http://www.ucfamerica.com/UCF WEBSITE LITERATURE/Leaf Spring Failure Analysis.pdf. It seems most of the cracking failure is around the center bolt followed by the u-bracket area. Other than that, it is general wear in work hardening and overall fatigue. As some of you mentioned, forging would resolve the general fatigue and stress issues.

Also, would it be possible to reveal cracks via any processes that involved etching the metal? And/or blasting media? Etc?
 
You can use a spark test, it gives you a good idea of how much carbon it contains. The color of the sparks give you an idea of what alloys are in the steel (yellow=low alloy).
 
Etching might, but media blasting could cause the crack to become more hidden unless it was big. Also I would suspect that the longer springs would be more likely to crack than the shorter ones. I would just avoid the center areas on the longer springs. If you did happen to use a piece that was cracked it I think it would show up on hardening. That brings me to the thought that if you had any suspicion the piece you wanted to use might have a problem you could heat it up to around 1500 and quench before you ever started forging it. If it cracks toss it.
The dye set up is fairly inexpensive. Next time I am around one of the testing companies I am going to ask some questions and see if I can get some for the good ol boy oil refinery rebate price
 
Looks like my free dream steel isn't quite what I had been hoping for. Certainly not 5160 anyway. What say you guys?

[FONT=&quot]C 0.425%[/FONT]
[FONT=&quot]Mn 0.83%[/FONT]
[FONT=&quot]Si 0.23%[/FONT]
[FONT=&quot]Cr 0.73%[/FONT]
[FONT=&quot]Ni 0.04%[/FONT]
[FONT=&quot]Mo 0.012%[/FONT]
[FONT=&quot]P 0.007%[/FONT]
[FONT=&quot]S 0.036%[/FONT]
[FONT=&quot]Cu 0.10%[/FONT]
[FONT=&quot]Fe 97.51%[/FONT]
 
Bummer, sorry Phil. Hey, I used to live on Oahu. I lived right across the street from the Hard Rock Cafe in Waikiki in an apartment. I went to Chaminade University up on the hill. What part of Oahu is your farm?
 
Hey Phil will this may help you to identify the steel and wheter its good to go!

http://www.admiralsteel.com/reference/cscomp.html

According to the chart if I am reading it right it puts it in the 1045 -1048 range.

No offense but, are you sure about that analysis, that is hard to belive its that low on carbon and still spring steel! I would have expected slightly more in a piece of spring steel but, there I go thinking again!
 
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@Dixieblade,
Spring steel needs to be somewhat hardenable, anything over 35 points is, in that application (looks like dump truck springs) it needs to be tough, the lower carbon steels are indeed tough.
M Wohlwend has a great idea. This steel has a lot of uses, just not edge holding

-Page
 
um, that's enough carbon for s-7... again not great on edge holding but hard use sword and axe potential. check out the manganese... it should harden well. INFI has low carbon too, also A8...
 
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