the first picture is of the full blade the second one shows just were is of the 2 aforementioned defects are. the blade was made from a leaf spring as I was working on figuring out how to get the L shape of the tang. i did this one by twisting it, however, I had to make sure it would not break off by welding and because of that i now make a shoulder to get that L shape.
The defects came about after I ran this threw a pine 2x4 and this was the only section that developed the edge defects. I circled the aforementioned edge defect using a paint program as they are a bit small and the forms picture limit makes them harder to see. I think these two little defects are from overheating those two spots well grinding it. the edge geometry is a flat grind as I recently realized have been doing flat grinds since I started making blades.
I only reasonably started making larger blades again so I have not really run to many threw 2x4s.
thanks for your time.
Hello Kevin,
The plastic type deformation exhibited on the blade is a classic edge wrinkle. The edge geometry is to too thin for the given heat treatment. You can either up the blade hardness, or increase the edge geometry thickness.
"One test is worth 1000 'expert' opinions" Riehle Testing Machines Co.
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Hello Kevin,
The plastic type deformation exhibited on the blade is a classic edge wrinkle. The edge geometry is to too thin for the given heat treatment. You can either up the blade hardness, or increase the edge geometry thickness.
thank you for explaining i have had a similar but more dramatic version of this on a blade. I hope you do not mind me taking up a bit more of your time with a few more questions. I generally tempered at about 430F and tend to trust the HT sheets as I can't afford a 2000$ hardness tester at this time (mainly cause I am stubbornly refusing to sell my work till I have passed the performance test for journeymen rank as the piece of paper shows that my blades are at least up to snuff with the abs's requirements for blade performance.) however, I can afford a set of the Rockwell C hardness testing files and I know they only test surface hardness but that's better than trusting the numbers. however I am unsure of there accuracy, so I am wondering if there worth there price?
thank you again for your time.
On the 430°F- What alloy are the blades made from? The files would be MUCH better than trusting most of the heat treatment sheets that are being provided with knife steel these days.
"One test is worth 1000 'expert' opinions" Riehle Testing Machines Co.
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On the 430°F- What alloy are the blades made from? The files would be MUCH better than trusting most of the heat treatment sheets that are being provided with knife steel these days.
Thank you once again for clearing that up I will get a set.
the alloy i used for this blade was is ford truck leaf spring as I prefer to use scrap to make a blade for the first time or if i am figuring out how to do something as it allows me to get an idea of how much steel i need to make a production piece or if it does not cost me 5 bucks or more if i screw up when trying to do something new. I think leaf springs are the same as flat springs and the automotive standards state this steel to be 5160 so I treat it as if its 5160. However, right now I prefer my 'production' blades to be made from 1075. mainly because I just like that its the closest to being pure eutectoid steel that you can get.(if memory serves right eutectoid steel has all the carbon desoveld in it at temperature) however, I am experimenting with 80crv2 right now.
I also stock 15N20, 52100, 1095, w2 (NJSB), and 1084. I am not sure if I will ever be a master of single steel as i like to make what I call grayscale damascus were I use 3 or more colors of gray in it.
i need to state that most steels feel the same to me under the hammer after i tried forging cast iron which i did mainly to see for my self just why you do not forge cast iron.
sorry for the information dump and as always thank you for your time.
hmm well the blade is between 50-55 Rockwell which was my goal hardness
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hmm well the blade is between 50-55 Rockwell which was my goal hardness
Hello Kevin, would there maybe be a typo there? That is far lower than I would want for any using blade, even a large chopper. Is that on the edge or on the spine? You can go with whatever hardness works for you but I would expect that range to wrinkle on a 2x4 just about every time.
"One test is worth 1000 'expert' opinions" Riehle Testing Machines Co.
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Hello Kevin, would there maybe be a typo there? That is far lower than I would want for any using blade, even a large chopper. Is that on the edge or on the spine? You can go with whatever hardness works for you but I would expect that range to wrinkle on a 2x4 just about every time.
(Blushing emoji here) it was user error I just got these files in the mail yesterday and I just used them for the first time today. I put to much force into them as I was testing the blade and that combined with the high polish resulted in an easy to scratch finish. its actually between 55 and 60 Rockwell and I was shooting for around 58 HRC by tempering at 430. Given I have never had hardness testing equipment of any kind I am not quite sure what the best HRC for a given application is. however, I topically like to temper at 400-430F. I may be jumping to wrong conclusions however my understanding of tempering learned via looking at the charts available from NJSB and figured for 5160 like material I was using that for every 25F above 300F steel will lose about 1 point HRC. I also prefer to temper steels for 2 1 hour cycles instead of 2 two hour cycles unless working with tool steel like w2 as i have read on the AMS heat-treating ap that w2 is steel that benefits from longer tempering cycles. I learned standard tempering in the steel industry is 1 hour unless otherwise indicated from dr. Verhoeven's book.
could decarbonization be happening at those spots in causing localized soft spots? asking cause I had this happen again but in one spot ground it out and it performed much better. i do not take measures to prevent decarbonization from happening so i am wondering if could also have contributed to this as the roll was in just one spot on a blade that was about 60 Rockwell going by files and heat.
I would not suggest making your performance test knives out of a scrap piece of metal. People scrap leafsprings because they have broken, which means they are probably full of stress cracks. You could very well just be wasting your time, abrasives and 2x4's on getting inconsistant results. If you have access to virgin steel, save yourself the heartbreak.
The grinder grooves on the blade would also cause inconsistancies on the bend test, so perhaps something to consider leaving out.
Lastly... Chopping through wood is pretty violent, and if your knife does fail, that peg on the back of the handle could end up embedded in some part of your anatomy.
Good luck. It's a challenging task.
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I would not suggest making your performance test knives out of a scrap piece of metal. People scrap leafsprings because they have broken, which means they are probably full of stress cracks. You could very well just be wasting your time, abrasives and 2x4's on getting inconsistant results. If you have access to virgin steel, save yourself the heartbreak.
The grinder grooves on the blade would also cause inconsistancies on the bend test, so perhaps something to consider leaving out.
Lastly... Chopping through wood is pretty violent, and if your knife does fail, that peg on the back of the handle could end up embedded in some part of your anatomy.
Good luck. It's a challenging task.
the material i used to make these the test knives is 1075. this one was made for fun and to try out a new technique that I refined via switching from a twisting technique to a soldering technique I just did not want to make a new post on this topic as i ran into this issue again with the first 1075 blade of this batch i tested.
