41V45 vs 4150 differences?

[Tspeis]

Title says it all. Just curious as to what significant differences there may be between the two alloys. I've noticed several manufacturers utilize 41V45 for use in rifle barrels (FN machine guns, Noveske N4 light, Ruger SR556, LWRC, etc...).

One article (I'll try to dig up the link) mentions 41V45 simply being Milspec 4150 alloy with the addition of Vanadium to increase tensile strength. Is this accurate or is there more to it than that?


Tspeis

[mblaney]

.....

[Tspeis]

Maybe this will help?
https://www.m4carbine.net/showthread.php?t=37

I appreciate the response. I did, however, already read through that thread. Unless I'm mistaken, I was under the impression 41V45 differs from 4150 CMV.

Thanks.


Tspeis

[lifebreath]

I appreciate the response. I did, however, already read through that thread. Unless I'm mistaken, I was under the impression 41V45 differs from 4150 CMV.

The referenced thread pretty much sums it up. 41V45 is basically 4150 with about 5% less carbon (hence 45 rather than 50), and the addition of vanadium and a slight increase in molybdenum.

The other vital aspect of the final products made from these steels is how they are annealed and otherwise treated (e.g. cryogenic treatment). The same steel can be given vastly different qualities depending on its treatment, and the different composition reacts significantly different to treatment.

[Eric D.]

This cannot be stressed enough. As an example, here is some data on C158. Notice how much the steel's tensile strength is affected by its hardness.

http://i.imgur.com/5FSb3.png


The other vital aspect of the final products made from these steels is how they are annealed and otherwise treated (e.g. cryogenic treatment). The same steel can be given vastly different qualities depending on its treatment, and the different composition reacts significantly different to treatment.

[Tspeis]

This cannot be stressed enough. As an example, here is some data on C158. Notice how much the steel's tensile strength is affected by its hardness.

http://i.imgur.com/5FSb3.png

Interesting. So with an increase in hardness comes an associated increase in core tensile and yield properties? I assume the hardness displayed on the chart is core hardness, not surface.

Thank you gents for the replies.


Tspeis

[Eric D.]

Correct. The surface hardness is closer to 70 Rockwell C.

More info on C158 here: http://www.cartech.com/

You have to create an account (its free) to view the tech sheets.


I assume the hardness displayed on the chart is core hardness, not surface.

[Suwannee Tim]

....Notice how much the steel's tensile strength is affected by its hardness.....

Hardness and yield are closely related measures of the same property. What's the point?

[Eric D.]

The point is that hardness is a function of heat treatment, ergo tensile strength is a function of heat treatment.

[Suwannee Tim]

I would say that strength is dependent on heat treat and hardness is a function of strength. It is certainly true that they are interrelated.

[An Undocumented Worker]

I would say that strength is dependent on heat treat and hardness is a function of strength. It is certainly true that they are interrelated.

On steel that rule definately seems to hold true, if there are any exceptions I am not aware of them. However you can have metals that are softer than a given steel, but have a higher tensile strength per a given mass.

So I guess what I'm saying is that harder does not always mean stronger, and softer does not always mean weaker. Infact if that chart extended further up the hardness scale there would probably be a point where you would find tensile strength drop as hardness increased further.

[Suwannee Tim]

....but have a higher tensile strength per a given mass.....

Tensile strength has nothing to do with mass.


.....harder does not always mean stronger, and softer does not always mean weaker. Infact if that chart extended further up the hardness scale there would probably be a point where you would find tensile strength drop as hardness increased further.

Hardness is a measure of strength. Harder means stronger, softer means weaker. The reason people measure hardness is because it is a cheap convenient way to measure strength.

[An Undocumented Worker]

Tensile strength has nothing to do with mass.



Hardness is a measure of strength. Harder means stronger, softer means weaker. The reason people measure hardness is because it is a cheap convenient way to measure strength.

After more research my confusion seems to stem from the differences between toughness and tensile strength, as it appears that you can harden steel to have very high tensile strength but at the same time very suceptible to being brittle like glass at the upper ends of hardenability.

As for the bit about mass, it was an attempt to explain a part made of steel could have a lower tensile strength of the same part made from a differnent material at even a lower weight. Although this doesn't really apply to guns, titatium comes to mind with it being softer than steel, yet stronger.

[careboy]

You just saved me the trouble of reposting.
http://www.primeaffiliate.com/track/images/22.gif
http://www.canadablackberry.com/imgs/images/2.tod.gif

[Suwannee Tim]

....you can harden steel to have very high tensile strength but at the same time very suceptible to being brittle like glass at the upper ends of hardenability......

Toughness is the ability of a material to absorb energy as it fractures. The opposite of tough is brittle and hard materials can be and often are brittle, glass being a good example. With steels toughness is seldom a problem at room temperature but can be a serious problem at low temperatures. I spent a summer as an intern for a nuclear company testing toughness of welds. The usual test for toughness is the Charpy test (http://en.wikipedia.org/wiki/Charpy_impact_test).

The reason hardness is an important measure is because it is cheap and easy to do and does not cause unacceptable damage to most specimens. Tensile testing on the other hand requires a prepared specimen which is broken by the test. Hardness testing equipment is generally cheaper and easier to use than tensile equipment.