Got a hold of some huge leaf springs! they are about 1/2 an inch thick and about 4 inches wide. Their length varies because it shattered. It is from a terra gator, which is a very large farm machine that umm.. well.. flings poo on farm fields. I was wondering if this would be good knife material. I will have to forge it unless someone wants a 1/2 inch thick knife.
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Leaf springs
- Thread starter AKboy
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No telling what they're made of. Seems like a guy on here got a hold of a couple of pallets of dump truck springs that ended up being 4140, not knife material. Not sure how much carbon is necessary for a spring of that size. Also, if they shattered, there could just as easily be cracks you can't see, in which case the whole lot would be good for paperweights or boat anchors.
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Couple things here.
There have been many discussions about recycled steel. Most agree that it is a crap shoot as to what the material is. You must either be very knowledgeable about testing and figuring out what type steel it is or have it analyzed to know what you have, if it is suitable for knives and how to HT
Plus, the fact that the springs are shattered would make me suspect that the rest of the pieces may well have micro fractures that might show up in the built or worse after complete and in use
There have been many discussions about recycled steel. Most agree that it is a crap shoot as to what the material is. You must either be very knowledgeable about testing and figuring out what type steel it is or have it analyzed to know what you have, if it is suitable for knives and how to HT
Plus, the fact that the springs are shattered would make me suspect that the rest of the pieces may well have micro fractures that might show up in the built or worse after complete and in use
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I don't think forging would help much. If you got the steel up to welding temps it might fix some cracks but not many because you would be putting the pressure on wrong. The cracks would probably be up and down in the piece and not in the horizontal plane. Forging sideways might fix a longitudinal crack, but not do much to a side ways crack.
It may or may not make them show better.
Steel type might have some effect but, I don't think much. Some steels forge weld easier than others.
Quenching would be more likely to cause the cracks to show up.
Probably the cheapest way to check for cracks would be to get a dye penetrate kit. Clean off the steel and put on some of the special red dye, then blow a little of the powder on with a little bulb and where there is a crack the red will show through the white powder.
Lot of work for a maybe, when you can buy known 5160 for less than $3 a lb.
It may or may not make them show better.
Steel type might have some effect but, I don't think much. Some steels forge weld easier than others.
Quenching would be more likely to cause the cracks to show up.
Probably the cheapest way to check for cracks would be to get a dye penetrate kit. Clean off the steel and put on some of the special red dye, then blow a little of the powder on with a little bulb and where there is a crack the red will show through the white powder.
Lot of work for a maybe, when you can buy known 5160 for less than $3 a lb.
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I'm the guy who got bummed out that his score of large leaf springs ended up not being the 5160 I hoped for. It seemed instead to be 5140 and not up to edge holding capabilities. [http://www.bladeforums.com/forums/showthread.php?t=691439]
As for your steel, the shattered part would likely be a deal breaker for me even prior to having it analyzed. Forging it to shape might help take care of fractures (especially if at welding temperatures), but I wouldn't count on it. There are penetrating dyes that can help reveal stuff. (See the thread linked above.)
Of course, if you don't have anything else to do and want to fool around with it, why not?
As for your steel, the shattered part would likely be a deal breaker for me even prior to having it analyzed. Forging it to shape might help take care of fractures (especially if at welding temperatures), but I wouldn't count on it. There are penetrating dyes that can help reveal stuff. (See the thread linked above.)
Of course, if you don't have anything else to do and want to fool around with it, why not?
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I believe Jim's the one that told me about the penetrant too. I picked up a kit off of eBay, but haven't put it too use yet. The steel didn't pass muster at the analysis phase of the venture so there was no need to go further. You could always hack off a small piece, prep it and send it in for analysis. That's what I did. It was worth the effort to me. Hey if it proves to be a good alloy you could just be in business for a while!
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I forged a knife from a piece of broken spring. Everything looked great after grinding, no sign of any fractures or cracks. I heat treated and it still looked ok. So I began finishing. There were some funny looking scratches that would not go away. After a couple of hours I got one side to 600 grit so I etched the blade. The whole blade was full of spiderweb cracks. Totally useless. I have the blade on my never again shelf.
This is one reason I have not been a proponent of used materials. i had about 4-5 hours into this project and 20 or so $$ in sandpaper and propane. For 20 bucks I could have had 8 or 10 feet of new material. Now just a side note, using brand new material does not guarantee perfect steel. I have had flaws that showed up in the final finish. However it does give you a much better chance as I have only had 2 knives do this. I now put the used material to good use for tooling etc.
This is one reason I have not been a proponent of used materials. i had about 4-5 hours into this project and 20 or so $$ in sandpaper and propane. For 20 bucks I could have had 8 or 10 feet of new material. Now just a side note, using brand new material does not guarantee perfect steel. I have had flaws that showed up in the final finish. However it does give you a much better chance as I have only had 2 knives do this. I now put the used material to good use for tooling etc.
Tai Goo
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It often requires a lot more “science” to analyze and optimize a salvaged piece of steel, as opposed to starting with a piece of new known store bought steel. In the long run, it can be a handy skill to have and an interesting study. However, in the final analysis the steel at hand may be suitable for the knife concept you have in mind or may not.
The important thing to remember is to check it out real well BEFORE you try and make a blade from it.
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I'm with Jim, Chuck, and Phil... if it was broken in service I would be wary.
If you really wanna go with spring material and on the super-cheap....You can go to a leaf spring shop and talk the guys out of some of their "drops" for just being polite, a box of donuts, or a 6-pack of beer.
There's a shop not to far from here that will sell, "However much you can pack out of here, on your own, in one trip, for $20" 
If you really wanna go with spring material and on the super-cheap....You can go to a leaf spring shop and talk the guys out of some of their "drops" for just being polite, a box of donuts, or a 6-pack of beer.
There's a shop not to far from here that will sell, "However much you can pack out of here, on your own, in one trip, for $20" - Joined
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Tai Goo
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The first thing you want to do is cut around the holes and fractured areas, and try to find a decent sample of it. If there aren't any then, yeah!,... toss it out. If you have a decent sample, grind/sand it off and check for surface flaws.
If you just dip the sample in water, wipe it off and let it slowly dry a few times, any small factures will usually show up as darker lines because of the oxidation.
If you just dip the sample in water, wipe it off and let it slowly dry a few times, any small factures will usually show up as darker lines because of the oxidation.
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