The ring of hardened steel

Nathan the Machinist

Nathan the Machinist

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There is a romantic notion that steel, once hard, has a certain ring to it. There are some folks who claim to be able to tell how hard a piece of steel is by its ring.

I have a number of very similar blades (CNC machined) some of which are dead soft, and some have been heat treated and are very hard. They ring and sound almost identical. The soft blades may have a bit better ring. I'm guessing because the random upsets and dishevels that is martensite may damp the ring a bit in the hard blades.

This leads me to the conclusion that hardness has little effect on the ring, and what effect it has is to reduce it a bit.

I made a skinning knife a few months ago that was ground very high (a bit above tangent) and very thin, much like a straight razor. It rang on the strop, which was cool. I'm convinced that was due to geometry, not hardness.
 
Oh, it is good to know. Most of the folks I know does this and my blades doesnt satisfy them :) May be too hard :p

Edit: I told this info to the neighbor (he always does the "ring test") he was surprised and said: "so the knives that I like were too soft then!!!"... I love to bust the myths around :)
Emre
 
I can tell how hard the steel is, what the alloy is and where it was made,... by the smell of it. :D
 
My anvil has a ring to it and I know I am getting a good weld when the billet starts to make the anvil ring. HMMM
 
To hear the ring of a steel blade in terms of hardness, you need a resonator and a file. I usually use my wooden work bench as the resonator, lay the back against it and come across the edge of the blade with a file. The chattering of the file will have a higher pitch the harder the steel is...

If you hang it up and ring it like a bell, geometry will have the greatest effect on the pitch.
 
DanGraves said:
My anvil has a ring to it and I know I am getting a good weld when the billet starts to make the anvil ring. HMMM
Click to expand...

That is probably due to the fact that once the billet is welded more of the blow's vibration travels thru the piece into the anvil. When unwelded the vibrations are scattered.
 
Sound tests are very useful to determine problems such as a cracked grinding wheel or a cracked bearing race.
For the "ring" you'd probably do better if you looked at frequency and attenuation.
For taste and smell only a trained metallurgist [not Tai Goo ] can identify a steel by taste and smell !
 
When I worked in tool shops we used to tell the apprectices that you could tell the different types of steel by the taste, the salter the taste the harder the steel, you would be amazed at how many kids licked a peice of steel:D

I don't know, thought it would fit .



cya
jimi
 
mete said:
Sound tests are very useful to determine problems such as a cracked grinding wheel or a cracked bearing race.
For the "ring" you'd probably do better if you looked at frequency and attenuation.
For taste and smell only a trained metallurgist [not Tai Goo ] can identify a steel by taste and smell !
Click to expand...

First I pickle it in vinegar to open up the full bouquet. Does that mean I'm a trained metallurgist? :)

Good point about the ring. If you hang it up, ring it like a bell and it rattles, you know you have a problem...
 
the discs i use to make my knives from will ring for a long time when lightly struck. i had a knife that would ring when i sharpened it on the paper buffing wheel.
 
Tai Goo said:
To hear the ring of a steel blade in terms of hardness, you need a resonator and a file. I usually use my wooden work bench as the resonator, lay the back against it and come across the edge of the blade with a file. The chattering of the file will have a higher pitch the harder the steel is...

If you hang it up and ring it like a bell, geometry will have the greatest effect on the pitch.
Click to expand...

I don't know if it really counts as a "ring," but I can tell a hardened blade by the sound it makes during the file test and at the grinder. Hardened blades have a glass-like sound to them.

Josh
 
I am not sure about the "ring" of a knife. My dad used to say you could tell the quality of an anvil by the way it rang when you hit it with a hammer though.
 
JoshEarl said:
I don't know if it really counts as a "ring," but I can tell a hardened blade by the sound it makes during the file test and at the grinder. Hardened blades have a glass-like sound to them.

Josh
Click to expand...

It's a type of ring, similar to playing a string with a bow.

The pitch will also vary with the speed of the file teeth running over the blade and the size and shape of the surface areas of contact. So, you have to take that into account too.

When hardness testing with a file, you can also look at the luster or lack of it from the file. The softer the steel is the duller and rougher the surface will be. The harder the steel is, you'll get more of a burnishing effect and it actually shines the surface a bit.
 
Having given this some thought and gone into my memory bank - there is a production test for bearing balls .This test is very simple but very accurate .It involves 'ringing ' in a way .The balls come down an angled shute, hit a hard metal plate , bounce up into a hole.Any ball not properly hardened will miss the hole !
I assume hardened steel would attenuate vibration less.The major frequency and harmonics probably different also. The Jamaican steel drums are made by hammering [hardening the steel] and they are tuned that way also !
Is there anyone out there who makes iron or bronze blades and hardenes the edges by hammering ? Do they ring differently before and after hammering ? Does you vorpal blade go snicker snack ??
 
Seems I remember a "down Home" group of musicians getting all sorts of noises
out of sawblades, washboards, and even jugs.
 
Just messing around a bit I have made bells out of copper. These were very small bells. when first cast they were a bit flat. after work hardening them they had a much nicer peal.
 
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