Is This Really a Tool Steel??

J

Jumbi

Joined
Mar 12, 1999
Messages
377
I just read an ad for a knife. It said, in part, "with a blade of .22 thick AUS-8A high carbon stainless tool steel at 57-59 RC..... I thought that AUS-8 was a relatively soft steel.

1. Is it considered a "tool steel"?
2. What are the common tool steels used in knives?
3. If it is a "tool steel" where does it rank?
Thanks
 
Jumbi :

[AUS-8A]

1. Is it considered a "tool steel"?
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I have seen 420J2 listed as a tool steel. I have yet to see a defination of a tool steel though beyond the very basic - its used to make tools. High-carbon does have a specific defination as does stainless and high and low alloy steels.

2. What are the common tool steels used in knives?
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O1, D2, A2 and M2 are popular.

-Cliff
 
AUS-8 is a relatively soft stainless, roughly similar in performance to 440B.

There is no such thing as a stainless tool steel.

By the way, RC hardness doesn't mean much when comparing different steels -- for instance, AUS-8 at RC 58 will not perform like a tool steel, say O1, at RC 58.



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-Cougar Allen :{)
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This post is not merely the author's opinions; it is the trrrrrruth. This post is intended to cause dissension and unrest and upset people, and ultimately drive them mad. Please do not misinterpret my intentions in posting this.
 
Cougar :

There is no such thing as a stainless tool steel.
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Have you seen a rigid defination of tool steel Cougar? It seems to be not well used if it exists. For example Livesay says his knives are "1095 high carbon tool steel". 1095 I would classify as a plain high carbon, or just a high carbon steel.

-Cliff
 
If tool steel is just a steel used in tools, then any steel used in a knife, from 420J2 to CPM 3V could be classified as a "tool steel," since knives are tools... so I've always thought it was sort of a meaningless description, sort of like "high carbon stainless."

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For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.

Romans 6:23


 
I was taught that tool steels were steels used in the tooling process to create other tools. Since this process usually involves cutting pieces of steel into shapes (a la CNC), the tool steel needs to be harder than the steel it is cutting.

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Glenn
 
Cougar, you say that two different steels won't neccessarily perform the same at equivalent RC hardness. Would this still be true if we were ONLY comparing edge holding ability and nothing else (such as how brittle 440A is at RC 59 compared to VG10 at RC 59)?

Also, I've noticed that most manufacturers now call any steel "high carbon" these days, when I thought high carbon referred to 1% C or higher. Perhaps "high carbon" is about as descriptive as "surgical steel" or "fast car?"

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-Gregory Zolas
tinsta@hotmail.com
 
Gregory, RC is just a measurement of how difficult it is to deform a material by impact. It is measured by hitting the material with something harder and determining the depth of the penetration. All materials with equal RC will impact in a similar way on flat surfaces as that is what RC measures. It is not trivial to relate the other properties to RC nor the behavior of blades in general.

Edge holding for example is not a direct function of RC. It is a function of strength and toughness primarily and resistance to impaction and wear resistance last, for knife blades anyway. For many cutting blades in industry the edge is so heavily supported with the motion so controlled that impaction and wear resistance are the key elements with strength and toughness not being very crucial.

-Cliff
 
The technical defination of "high carbon" is any steel with 0.6% carbon. These are steel that can be hardened to 60+ on the Rockwell C scale. As opposed to "medium/mild carbon" which are often 0.1 - 0.5%. The amount of chromium in the steel has no effect on the terminology.

So anything better than 420 is technically high carbon.

"Tool steel" is used for tools, it's supposed to be more complex than plain 10XX, and have better quality control. But it's just an informal name, like "spring steel".

 
Thanks, Cliff. Is there a standard for quantifying impaction and wear resistance? I would guess not, or it would be referred to frequently in knife circles.

RC, if not directly related, is still the only measurable factor that plays a roll in edge retention then, as long as it is taken in context to the type of steel?

Thanks again. Good info!!

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-Gregory Zolas
tinsta@hotmail.com
 
A really really really cheap screwdriver is a "tool." :-)

I guess I'm trying to say there are also crap tools made out of crap tool steel.

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Totally new website!
www.wilkins-knives.com
 
Happy Camper:

RC, if not directly related, is still the only measurable factor that plays a roll in edge retention then, as long as it is taken in context to the type of steel?
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All the factors can be measured, you can get quantitative statistics on strength, toughness, ductility and wear resistance. To be very blunt, it is rare to see this because it prevents hype and overpromotion. In general the more vague someone is about their products abilities the further you want to stay away from them.

-Cliff
 
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