I think ruger was basing their preference on SS over non SS by shear testing lugs on bolts from each type of steel. Obviously it took more force to shear lugs off the bolt body of SS. Would this not be a measure of toughness or a combo of hardness and toughness? I was led to believe hardness had a linear relationship with brittleness, which would probably not be good for lugs/bolt bodies. I have forged down some SS round stock to very thin sections and was amazed how it did not fatigue and crack like mild and even some tool steels. Metal is an interesting subject...
In the pure sense of if, toughness (or fracture toughness) and shear strength are two different things and are described with different units of measure.
I can understand that toughness as general term can be, and are, interpretted differently. That is why I wonder what Ruger means by tougher. I'm thinking they mean one is better than the other (tougher), so yes it could be the combination of shear, toughness, and hardness. It is the property (or properties) they are measure or comparing to determine the superior product I would like to know.
As to hardness and brittleness being a linear relationship, I wouldn't be able to provide an expert opinion. My thoughts, within a group of metals it maybe but don't think that would be a good general statement.
Having to much hardness can be bad, especially throughout the entire thickness. Surface hardening on the other hand has some major benefits.
You have me going .. best I stop at this.
Cheers .. and yes .. its incredible what they can do with handful elements these days.[/QUOTE]
Hey, just stolen from a google search! Toughness is actually a term like hardeness etc. On a side note I have heard there have been some barells made from non sulfur SS using specialized equipment. If these were ever produced, cost effective, they should last longer than chromemoly perhaps.
Toughness
The ability of a metal to deform plastically and to absorb energy in the process before fracture is termed toughness. The emphasis of this definition should be placed on the ability to absorb energy before fracture. Recall that ductility is a measure of how much something deforms plastically before fracture, but just because a material is ductile does not make it tough. The key to toughness is a good combination of strength and ductility. A material with high strength and high ductility will have more toughness than a material with low strength and high ductility. Therefore, one way to measure toughness is by calculating the area under the stress strain curve from a tensile test. This value is simply called “material toughness” and it has units of energy per volume. Material toughness equates to a slow absorption of energy by the material.
There are several variables that have a profound influence on the toughness of a material. These variables are:
Strain rate (rate of loading)
Temperature
Notch effect
