metallurgy of blue vs. stainless

[MyRoad]

The obvious advantage of stainless steel is that it is *less* likely to rust.

I'm wondering if there are any other differences in the characteristics of the metals, for instance in terms of barrel harmonics or stiffness? Or the flexibility vs. rigidity/hardness or overall strength of one metal composition over the other?

It has seemed to me in the past that some guns I've had that were blued had more MIM parts, and it seemed like the SS counterparts were all machined parts (mostly with 1911's) -- can stainless be molded or only milled? I could be totally wrong on that observation, so I'm just checking.

Once again I'm contemplating spending more money on a SS version of a rifle, and wondering if the rust-resistance is the only advantage.

 

[rcmodel]

No difference in stiffness that I know of.

Lots of guns are molded, and stainless.

The whole Ruger line-up is molded/cast.

http://www.ruger.com/casting/PDF/PineTreeCastings.pdf

rc

 

[Dframe]

I don't know of any significant stiffness or hardness issues. I've been told the granular structure is different and makes machining stainless a bit more difficult.
Ruger has been using investment castings for decades now, since it's cheaper than forging.

 

[MyRoad]

I've had two AR's that were "precision" rifles, one with a bull barrel, one with a "match grade" heavy barrel, both were stainless. That's what made me wonder about the characteristics of stainless, and if it was random or with reason that both of these rifle makers chose stainless for their precision barrels. But I suppose there are just as many non-stainless match barrels, and possibly it was just what was in fashion at the time I bought them.

 

[desidog]

Stainless can be a bit more brittle, but unless you are discussing certain metallurgic make-ups, stainless vs non is too broad a topic, with the spectrum of metals out there.

Just go to the hardware store, bring a magnet, and see which "stainless" fasteners are magnetic...US- vs. Chinese steel is a whole 'nother situation.

 

[MistWolf]

Stainless steel barresl are not more accurate than their chromoly counterparts, but because of the way they erode, stay consistent longer. But when the erosion finally affects accuaracy, it's all at once. Chromoly barrels erode slowly & evenly and lose accuracy gradually

 

[joeschmoe]

It used to be true that you could generalize attributes of carbon vs stainless steels. Not any more. Modern steels can be made to match any desired characteristics so that there is no difference from the users perspective. In general the combination of hardening process with the correct steel and fabrication method is used to achieve the desired outcome. If there is a failure, or shortcoming, it is due to one of those factors, not just because it is either SS or carbon steel.

From the users perspective, the only real difference is corrosion resistance or appearance. From the manufacturers perspective there may be huge differences but mostly due to costs.

 

[NuJudge]

Stainless is stainless because of its chromium content. Chromium tends to hurt impact toughness. I have a Interarms Virginian revolver in stainess that has a forcing cone that split like a collet, as a result of this.

Stainess finishes tend to 'smear' during finishing, so you don't see many high polish stainless finishes.

There are not a lot of heat treatable grades of stainless. A lot of non-heat treated steels are not resistant to a cyclical cracking and failing phenomena called 'fatigue.' Quenched and tempered microstructures typically are very resistant.

Given my choice, I prefer a heat treated chrome-nickel-moly material for a highly stressed part, but then again, if you are going to be in the cold/wet for weeks, go with stainless.

 

[fletcher]

I'm wondering if there are any other differences in the characteristics of the metals, for instance in terms of barrel harmonics or stiffness? Or the flexibility vs. rigidity/hardness or overall strength of one metal composition over the other?

It varies a tiny bit from alloy to alloy, but stiffness between stainless and low alloy steels is comparable. For the types of metals you're likely to find on a firearm, I wouldn't expect much difference between the two. A low alloy steel will generally be better from a wear perspective (due to larger volume fraction of hard phases), but it varies depending on individual alloy composition and heat treatment.

can stainless be molded or only milled

Stainless parts can be made using MIM.

 

[MyRoad]

Thanks for all the good information, everyone.