Is there a difference

[Raymond Richard]

between a forged and a stock removal blade? I found out for myself this morning. Now I see the need to do this test one more time. Up until a couple weeks ago when I forged a blade I'd just grab what ever size bar I needed and then forge a blade out of it. I've been doing a lot of saw steel and using a pre form to start with since the steel was fairly thin. I just didn't feel like I was forging doing that so I remember back several years ago when I would forge the width back into it self to give me a thicker piece of steel. Now I've been doing that everytime I forge and when I get done doing that I just felt like I had a better piece of steel. I decided to do a test and see if the extra work made any difference in the way the blade cuts. Anyway I started with a piece of the Comet leaf spring that was 3" X 1 3/4 X 1/4 and forged it into a bar that was 6 X 1 X 1/4 and then I forged the blade. I used that blade for a pattern to make a stock removal blade. Everything was done identically to each blade after that. It had been several years since I did a stock removal blade and I was shocked at how little time it took me to make that blade and wondered if all the forging I do is worth it. This morning I went and bought 10' of 1/2" sisal rope and did the cutting test. My thoughts were that I wouldn't find much difference between the to. Was I wrong. I got 50 cuts on the rope with the stock removal blade and that was after re sharpening it. I got 225 cuts with the forged blade before I ran out of rope. Next test will be for me to forge another blade out of the leaf spring and just go about it my normal way with out hammering the width back into itself.

Here's whats left of the rope

[Ray Rogers]

What about the heat treatment of the stock removal blade? I'm sure you heated and quenched it just as you did the forged blade. But, when you made the forged blade were there normalizing cycles? If not on purpose, maybe just the fact the steel was heated and cooled several times as you worked it might have had a normalizing effect and produced a smaller grain size. If you think this may be true, normalizing cycles could be added to the treatment for the stock removal blade.

If hammering the steel back into itself does result in a better blade then I would imagine that starting with a thicker bar and hammering it down to the desired thickness would also give a similar result if the reduction in cross section was at least 1/3 of the original thickness. This seems to be the magic number when I read how forging changes the properties of steel. Try a blade this way and see how it compares.

Repeating your test with another type of steel might also yeild interesting results. I'm very curious about what you will find.....

[toddhill]

Very interesting, Ray. This is good stuff--when testing leads to discoveries. You're helping us all out by doing your tests. Thanks. Todd

[Raymond Richard]

Ray, I did the normalizing with both blades at the sametime and heat treat was identical. Both blades were normalized 3 times and allowed to cool off all the way. What I did to one blade was exactly the same for the other except the matter of the forging the way I explained it in the first post. Ed Fowler is always saying his blade stock is forged down from much, much larger stock and he believes it makes a huge difference besides the fact that it is 52100. I just forged another blade out of the same chunk of leaf spring except I just forged it like normal and then I'll heat treat it the same as the last two. The I'll test it against the other blade. Not much energy today so hopefully I'll get it heat treated tomorrow.

[Tai Google]

Of course there's a difference!

If you do different things to them,... there's a difference.

[Tai Google]

It's like I've been saying, the steel "records" everything you do to it. Everything you do to it has an effect on it.

There is a lot going on in the forging process,... heating, cooling, shock, stress, forming, shaping, bending, flexing etc.

What you need to do is count the number of heats, and hammer blows and try to calculate exactly what the overall forging process encompasses...

There are so many variables involved with the forging process that it can be difficult to determine what part of it had what effect? I think we can get into trouble if we don't examine it from every angle.

You can stretch a piece of steel without any hammering. What you do is heat it up, jelly roll it around a jig, and un-jelly roll it. If you repeat this process you can stretch it further. There's lots of things you can try.

[Tai Google]

On the other hand,... why ask why?

It's a pretty darn big can of worms! It could all just be a "thermal reaction" to the overall forging process.

You could just say that a properly forged blade will out perform a stock reduction blade,... for whatever reason or combination reasons and leave it at that. It's simple and straight forwards.

There are limits to what good forging can do, and there is a point where it can do more damage than good. Also, for every action there is an equal and opposite reaction.

Blades need to be tested in the short run and in the long run. High performance in the short run could also equal a shorter life of the tool and premature failure.

All the testing in the world doesn't mean anything,... unless the information is properly "interpreted" and applied.

[Blaine Whitney]

Originally Posted by Tai Google

It's like I've been saying, the steel "records" everything you do to it. Everything you do to it has an effect on it.

There is a lot going on in the forging process,... heating, cooling, shock, stress, forming, shaping, bending, flexing etc.

What you need to do is count the number of heats, and hammer blows and try to calculate exactly what the overall forging process encompasses...

There are so many variables involved with the forging process that it can be difficult to determine what part of it had what effect? I think we can get into trouble if we don't examine it from every angle.

You can stretch a piece of steel without any hammering. What you do is heat it up, jelly roll it around a jig, and un-jelly roll it. If you repeat this process you can stretch it further. There's lots of things you can try.

I still think if you took an identical piece of steel, and hit it with an exact duplicate amount of blows, file strokes, heats, quenches etc......you'd still end up with 2 slightly different looking blades. At least I would

[Tai Google]

Originally Posted by Blaine Whitney

I still think if you took an identical piece of steel, and hit it with an exact duplicate amount of blows, file strokes, heats, quenches etc......you'd still end up with 2 slightly different looking blades. At least I would

Good point! It's not an exact science.

It takes skill, and "intuition" to be a good bladesmith.

Metallurgy is just a tool, which can be used beneficially or un-beneficially. It becomes un-beneficial and misleading when it is improperly interpreted and applied.

You can never learn or understand it all.

...There's good metallurgy and bad metallurgy.

[Bob Ouellette]

wow, this is all very interesting. I don't think I'll ever find out the difference in my own blades because doing stock removal with files doesn't seem like it would be worth the effort when I have access to a fire, hammer and anvil. But I'm interested to see more.

[Ray Rogers]

I think it would be good to know the why of it but, at least in theory, I agree with Tai that knowing why isn't as important as know how to get the result.

What interests me in this thread is that I don't accept at face value the statement that a forged blade is 'better' than a stock removal blade. Perhaps it is true, but it is counter intuitive for me and it doesn't agree with some of what I've read before. On the other hand, I don't know that I have ever seen a comprehensive set of tests done on the subject.

I think these tests can give us a strong indication of whether or not forging makes a 'better' blade if we don't start out expecting that to be the case. Even real scientists have to fight the urge to unconsciously bend the data when trying to prove their pet hypothesis. It is interesting to speculate that perhaps if someone were to set out to prove that there was NO difference or a very small difference their results might be skewed in that direction.

There may always be shades of gray here as well. For example, why is it that two makers can make similar blades from the same steel and use the same type of heat treatment and yet the blades may not perform in an identical manner? Normal variance. Can the difference in the performance of forged and stock removal blades be brought into the range of normal variance ? I don't know, but I'm looking forward to Ray's further experiments...

[dave Stifle]

What I do not understand about Ray's test results is the large difference in results he got between the two blades. I can accept that one or the other may be better, but that much better? I always thought a knife was a knife, and the heat treatment is what determines it's performance (all other things being equal, i.e., same steel, etc).

Dave

[Tai Google]

With smithing, If you eliminate the "human" factor,... you eliminate the smith!

The vibrations of the smith himself!

It could be, "HADO"!
https://www.hado.net/hado/index.php

[RHGraham]

when they stop forging crankshafts for every single diesal engine made for the highways and every high-performance car on racetracks, any brand-name wrench that's worth having, every set of wheels on a train, maybe I'll give up on forging.

:0)

To be "politically correct" in the blade world it should be pointed out that an awfull lot of steel used for "stock removal" blades is forged... it was rolled at a mill from large ingots.
There "shouldn't" be much difference if the heat-treats are the same.... but I personally think that some don't realize that forging can be part of the thermal treatments as well, and I certainly think this can play in the whole deal and create some differences like what Raymond saw with his tests.

Thermal cycling is good, I think.

but anyway, my forged blades are better than the few stock-removal ones I've made. Might be just me, or maybe there's something to it. Helluva good subject to create some entertainment with at a hammerin or knife show in any case.
I don't know about edge-holding, I think though that a forged blade *can* be stronger or tougher than perhaps a straight stock-removal blade that's comparable otherwise.

I'll go flaggelate myself now for uttering such a sinfull thing....

[Raymond Richard]

My other test blade is in the oven now. It was forged my normal way right out of the bar. No hammering in the width this time. One thing I did do is call a rope supplier. I'm getting a 1220' spool of 3/8" sisal rope. This way I won't have to run to the feed store every time I want to test a blade. I'm still shocked myself in the huge difference in the amount of cuts the forged blade made over the stock removal one. I'll keep everyone posted on how this next test turns out.