Re: LOOK FOR 6 SCREW STEEL RINGS
The applicability of that heat treat is nil for scope rings. That material spec is so hard, so brittle that it is extremely expensive to machine and hold true when manufacturing. Plus it is prone to low stress fatigue cracking in vibration environments.
That nails the point I made about going to an extremely high strength alloy being far more expensive to manufacture and driving the cost of a product up significantly only to match the capability of the AL 7075-T65.
It also illustrates that you have no experience in actually designing and analyzing things for failure. How about you post up your experience and qualifications level for such an argument?
I have 2 suspicions regarding you.
1) You're a keyboard commando who's busy wiping cheeto stains on his sweat pants in his parents' basement while searching for the highest yield strength steel you can get to post it as a pseudo-proof against AL.
2) OR, and this is a much stronger suspicion: You are somehow connected to a steel alloy scope ring manufacturer/supplier and you have a financial interest to pushing steel rings as the best solution to any kind of scope mounting issue. You're playing a schill game to blow smoke and nonsense because you're afraid of the market share disappearing as modern manufacturing techniques and superior designs for Aluminum alloy, high strength, aerospace grade materials are applied to a product which has for many years been an afterthought to a lot of people.
In reality, the application of 52RC 4140 with an 8% elongation to ultimate failure (not yield, ultimate) would be completely irresponsible of an engineer in this case because the vibratory environment is going to crack the rings over time.
Additionally, that 225ksi yield strength only gets you to break even capability on specific strength with 7075-T65, but you just drove the cost through the roof with near net machining, through hardening, then post machining the parts and trying to hold them and cut true geometries with 52C material. Likely you'd be forced to have the mating surfaces ground for a precision fit instead of simply cutting them from the AL that you so despise. Grinding is not cheap, nor is it fool proof.
You wanted real numbers, so here's some numbers that are actually applicable to the question at hand. Note carefully that those special FN rings you keep touting are not listing a heat treat, just that they're 4140. You're the one who pulled a narrow bar allowable that is in a shape too small to cut rings from. The bigger the bar, the lower the attainable hardness because of the material quench rate and the heat removal rate during quench.
Here's a look at the material spec quoted for "heat treated 4140".
73ksi yield, 0.102 lb/in^3 --> 73/.102 = 715.7
60ksi yield, 0.284 lb/in^3 --> 60/0.284 = 211.3
735.3/208.3 ~3.39
AL 7075 T65 is appx 3.39x's the specific strength of the material spec that you quoted. However, those material specs quoted on the AISI 4140 seem a little low for a high strength heat treat spec on this steel.
Here's a real material spec to work from: (Anyone can access these online)
AISI 4140 Steel, normalized @ 870C, air cooled, 50mm round
Ultimate = 141 ksi, not 95ksi
Yield = 92ksi, not 60 ksi
AL 7075-T651
Ultimate = 83 ksi
Yield = 73 ksi
Taking a look at the specific strength comparison once again with actual material specs:
AL 7075-T65 (carried through from before) = ~735
4140 from above linked spec: 92ksi/0.284 lb/in^3 = ~324
Which still leaves a comparative difference of 2.21x's in the favor of AL 7075-T65 over the same exact design in Steel.
Your special material, even when the expense is taken to manufacture the parts from that material are a BREAK EVEN PERFORMANCE but the PRICE IS HIGHER.
Win to Al 7075-T65
Your pseudo-intellectual ability to pull inapplicable data is indicative of a severe lack in experience. This is a lesson that young engineers learn in the first 3 semesters of engineering school.
So, again: What are you qualifications?
ETA:
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: paw print</div><div class="ubbcode-body">TPS among others does make Ti rings! Stronger than steel, never rust, just won DoD contract to ship overseas. </div></div>
How about some "real numbers" to prove that those Ti rings are stronger than the steel? Sounds an awful lot like you're making claims that you are such a champion against.