Sounds And Durability Of Steel

Recalling the years of my youth when farmers, blacksmiths, and trades people used materials at hand to fashion necessary tools required to deal with every day chores, I recalled that there was talk about the way steel sounded against a sharpening steel or stone - that a dull sound meant one was good while a more ringing sound indicating a poorer steel. That could have been the reverse statement - just can't recall exactly. Steel then as well could be bent and then hammered back straight again, not snapping off like some of the knife points I have used today do. I realize a knife was not intended to be used in a manner that would expose such a risk, however, the reality is it happens sometimes. Could I impose upon the viewers and the members here to offer an opinion or two.

 

I am not a metallurgist, but I have studied a little bit about these things. Probably "just enough to be dangerous" as my Mother would say.

When honing longer thinner blades against a strop they make a nice ping sound especially at the end of the stroke and the tip of the blade becomes free from of the honing surface. It's like the sound you hear in movies when there's sword play "shhting" but more subtle and way less glamorous. I think this ringing has more to do with the mass and length of the blade as I've never heard it on short thick blades irrespective of the steel type or hardness. The first time I noticed it was on a Nitro-V 3/32" chef's knife with a 9" blade and distal taper.

As for bending a blade goes, I've always understood that malleability and hardness to be sort of opposite properties in steel at a given temperature. Example, take a butter knife (no so hard) and bend it in the vise. Voila! Nice and bent right? Now grab a quality paring knife (hard) and do the same thing. Snap! Paring knife is in two pieces. I have never been able to successfully straighten a bent blade without heating it to near tempering temperature. Heat increases malleability in metals. This is why straightening operations are almost always done while the blade is being heated. In short. You can straighten out a lower hardness knife with a hammer, whereas a higher hardness knife is more likely to yield (snap).

But one has to be careful as heating too much will permanently lower the steel hardness, what I call "killing the temper" and rendering the blade more like a spring. Interestingly, this why a great knife steels like 1084 and 1095 are sometimes listed in catalogues as "spring steel." Temper low = hard. Temper high = spring. The magic of carbon in steel.

Also, hardness is often confusingly associated with sharpness. The reality is that we could, with a little effort, sharpen that same butter knife to cut like a paring knife or even shave with. However, because it's lacking hardness (resistance to abrasion) it wouldn't stay sharp for long under use.

Thanks for opening the can of worms.

 

Is there a steel that can not be as brittle as another and still have the sharpness and edge retention or is that the tradeoff that we contend with?
Thank you for that explanation, in particular the statement " You can straighten out a lower hardness knife with a hammer, whereas a higher hardness knife is more likely to yield(snap)" Really helps to understand it that way.

 

Not a single steel that is uniformly heat treated. Luckily in ancient times humans figured out some ways around this problem when making swords. One is to cool the steel at different rates during the hardening process. Let's say we edge quenched a piece of steel so the cutting edge was in the oil while the spine was cooling much slower in the air. If the edge quenching is done correctly the cutting edge will be hard while the rest of the blade will be softer. Another trick is to temper the spine of the blade at a higher temperature than the cutting edge. Yet another technique is to use two types of steel. One is high carbon and hardenable; the other is low carbon and not hardenable. Take the different types of steel and construct a lamination. A San Mai blade has a hard high carbon steel core where the cutting edge is and this is clad with softer low carbon steel jacket.

 

I was at and obtained from a garage sale a while back an old Frosts Mora Classic 2 style blade that is purported to be laminated steel. I found it very easy to sharpen, takes a real razor sharp edge. It was in pretty rough shape, mind you but one thing I noticed is the spine when squared off to strike a fero road will not create any sparks as a high carbon and/or stainless blade should. Your explanation I take it would explain this design composition.

 

A hard steel will ring or vibrate same as music wire will. One test knife I have hear and it's field test counterpart have a very noticeable note to them, the catch well they will take a polish from a hone and you curse when sharpening.

physics behind it is simple? well think of quenching as causing the steel to tighten up like a drum skin.

 

Yes, some Scandinavian knives are made of a two steel laminate. If it's a foldover then the whole spine will be softer steel.

 

"Quenching causing steel to tighten up" I like that comparison as well. Thank you for these reponses, Dan and John - questions I have really wondered about over my involvement with knives, not so much as a builder or crafts person but as a user who like family members before me, early 19th century or so, wanted utility in a hunting tool, in the butcher shop - just a down-to-earth reliable and almost indestructible device, used in a responsible manner. As I will keep saying from time to time, I sure wish I started this 50 or 60 years ago.

 

If you like experimenting you can get a piece of steel a couple inches long.
1- place in vice lengthwise
2- snug the vice up
3- heat a strip on the steel parallel to the jaws face until it is orange or slightly lighter

You should hear the jaws tighten up from the heat expanding the steel.

4- Allow the steel to cool

The steel will fall out of the vice before reaching room temperature.
This happens because as the steel is heated and expanding it has no where to go and the material is compressed

 

I think what really piques my interest in opening this conversation was recalling a few years back while assisting relatives in an impromptu set up garage butcher shop, cut up, and process some animals from a recent hunt. It was a family event and as we were operating around a large worn butcher block which had slots on the side holding several old skinning, boning and butcher knives. The elder statesman of the group, reached over, picked up a sharpening steel and proceeded to hone his knife of choice which, of course led to everyone else who were using similar knives turn theirs over to him for resharpening.

His comment to us was: no time like the present to learn and we did. He told us you won't hurt these knives but don't use 'em 'til you have 'em sharp. Of course, that led to conversations about where these tools had come from. Apparently they had been made by his Grandfather, who had been a blacksmith which likely would date them back to late 1800's or early 1900's. He was pretty sure the knives were original, with the original handles and, as I recall all had a sort of flat grind however, I am sure by that time had a convex edge. I guess these days you would say they possessed a beautiful patina, old Uncle just said they were rusty.

You know, I still hunt with relatives of old Uncle and we manage to all get together at least one day of the hunt to reminisce with the new generations and the talk will still get around to guns, knives, clothing etc. And, on more than one occasion, some of those remaining old knives will surface doing kitchen duty inside the camp and processing duties in the storage shed outside the camp. Files were used to reprofile blade shapes which really narrowed the widths, but the sharpening steel kept it honed.

These knives looked terrible, and, yes, I guess you could say rusty. The wood handles had a natural finish which was likely a combination of sweat, blood and oil, but they did their job, were not bent, mostly flexible and all still in tact.

Maybe today with all the steel and formations available, our forefathers might not need a file, a steel or an old grinding wheel.
For some reason, though, we still need to work blades to keep them doing the job, don't we?