Knife Talk Online Forums

KNIFE TALK => Ed's Thoughts => : Ed Fowler January 16, 2018, 05:21:30 PM

: Knife for springs test.
: Ed Fowler January 16, 2018, 05:21:30 PM
Every year we have a get together of HEPK Smiths who wish to bring something that they have made that will have some special kind of treatment that will reveal something different to those who want to test it. This is my first knife that will be tested, it was over heated before quenching and left a super hardened area that climbs right to the spine. We will test it to destruction this spring. I invite all who are interested to bring something special and share in the learning from what it has to teach us.

: Re: Knife for springs test.
: mreich March 06, 2018, 11:22:25 PM
Ed, I can't delete this blade from my memory bank. It's just gorgeous. I love every curve she has, and the plunge line is.... well, it's better than a low cut blouse.

I totally understand what it feels like to accept something you've already rejected, so I can't ask for this blade. I would if I could though.

I realize it's probably just me, and I know you've made hundreds of "perfect" blades...

: Re: Knife for springs test.
: Ed Fowler March 10, 2018, 06:04:47 PM
You can have her after the test, maybe you could straighten her out and get some use out of her. Actually I have other blades on the way for you to chose from, handles and all!! But she will be here or with you, looking at her she really has quite a story to tell, I will try to get some better photos and post them up.

To be honest I kind of like her myself!!

: Re: Knife for springs test.
: mreich March 19, 2018, 02:44:34 AM
Ed, I've been thinking this ever since you posted a picture of this blade, but I haven't said anything.

Really, those shiny spots look a lot like simple decarb to me. Yes, decarb goes deeper if you get something a little too warm, but I don't think it hurts the underlying steel at all.

You can see whether or not it's decarb even with low power magnification, like a 10X loupe. The surface will look kind of like a layer of shiny, teeny ball bearings. I don't know how else to describe it.

If you take the surface back down to 220 grit, then progress with the finish as normal, at least in my experience, those shiny areas will totally disappear with the subsequent etch.

I don't think it matters to the underlying steel. It's not like you can hold it at a high temp long enough to cause grain growth at all.

I'm just been thinking about it for a while, trying to imagine what could cause the shinier spots, and remembered that's happened to me.

You know, we had the spring rendezvous on the first of April last year, and Annie and I liked to spend our anniversary down there with our friends. :)

Also, I designed a new blade clamp for torque wrench attachment, and I'm eager to see what you think of it!

: Re: Knife for springs test.
: Ed Fowler May 06, 2018, 03:33:35 PM
We used your additions to the HEPK tests and they were greatly appreciated, will add some photos of them when time allows.
This is the test blade pictured above, it made 15 edge flexes with no chips, then 4 180 flexes starting with 62 foot pounds of torque, when it  finally cracked. I have sent the blade to Rex and we should be hearing what he can read with his laboratory equipment.
What we know now is that we can see 5 different phase changes in the blade in the crack, it was very strong, tough did all I expected of her. We could have easily straightened the blade and used it again, can't wait to hear from Rex.

: Re: Knife for springs test.
: brad westring August 01, 2018, 04:07:46 AM
Ed, Could you tell me what you are seeing in the crack that let's you know it went through the phase changes? Different grain structures?

: Re: Knife for springs test.
: Ed Fowler August 02, 2018, 07:25:43 PM
The jagged tear indicates that the blade did not break through grain, it followed grain boundaries.  While you can see the larger changes in direction, with magnification you get to see many individual changes of direction. The blade was quenched as close to critical temp as I could manage, Rex stated that the phase changes are indicative to banding, both chemical and structural banding with fine grained martinsite and coarser pearlite. The bands twist among themselves according to Rex.

: Re: Knife for springs test.
: Ed Fowler August 02, 2018, 11:00:57 PM

This is a photo of one of my experimental knives, this pattern just showed up on one side, but I knew I was getting there. When I etched it, I was very satisfied, I believe I have achieved an attribute of some of the old wootz knives where in the man that made the knife signed it so anyone in the know would realize who made it.

The design you can see in this knife is an honest representation of the structure and chemistry of the steel, it was all developed with heat from my oxy-acet torch. The blade started out as a 6 inch round bar of 52100, was drawn down to this size, a rate of reduction of about 98+% at low temp. 1625 f. being the top forging temp. Many thermal cycles and the multiple quench process.

I call this pattern, "Starry, Starry Night" after VanGoe's masterpiece.

: Re: Knife for springs test.
: TomWhite August 08, 2018, 04:46:20 PM
That is a beautiful knife. The reduction is unreal, it's hard to imagine beating down a piece steel that much.

Sorry, the copyright must be in the template.
Please notify this forum's administrator that this site is missing the copyright message for SMF so they can rectify the situation. Display of copyright is a legal requirement. For more information on this please visit the Simple Machines website.