Wow, I'm not reading this whole thread but forgings are stronger than the same sized/shaped casting. I mean really is it that hard to understand?
Maybe you should do more reading.
examples:
Car parts - universally known that forged cranks and pistons (as well as other parts) are stronger than the cheaper cast versions. I'd love to see some of ya'll try to tell some racers, teams, mechanics that cast is better...
Well, you aren’t really comparing apples with apples, nor are you looking at the right property in those examples. If we compare a forged steel crankshaft or con-rod with one of conventional spheroidal graphite or nodular cast iron the forged steel will generally be significantly better, at least for racing and high duty. That is not because of strength though but resistance to fatigue failure, which is admittedly much better for forged steel than any cast iron or even the general run of cast steel.
Fatigue is a big factor for cranks and rods, but not rifle receivers: a crank and rods will undergo more load cycles in a few seconds at full noise than a rifle receiver will undergo in its entire service life. That is why as well as specifying a forged crank your tuner will also be obsessive about radiusing all corners, shot peening and polishing, crack testing, and balancing, all to reduce the likelihood of fatigue cracks being initiated. None of this is relevant to rifle receivers.
There are better materials than these for racing car components too, such as Metal Matrix Composites, already seen and then banned from use in F1 pistons. MMCs are generally produced by casting or else powder metallurgy, and have particular advantages for pistons due amongst other things to the thermal loads.
F1 engines do use investment castings in the form of valves, valve-train components, blocks, gearbox housings and a myriad of others. The rules specify a steel crank though, so that is what is used.
Aircraft - once again all critical parts (that are metal) are forged for strength. I guess you guys need to tell Boeing, Lockeed, etc. that their wasting money not using cast parts because heat treating is somehow going to work majic.
Heheh – no need to tell them, they already know
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In fact about 10 years ago Boeing’s CEO gave an interview which he circulated to the company’s engineers to the effect that they should begin a targeted program to replace forgings, assemblies or fabricated parts with cast components. Among other things he expressed the view that Boeing could achieve a 20-35% reduction in tooling alone by converting a fabricated assembly to a cast component. Boeing has put that approach into effect very successfully.
And Lockheed?
Fort Worth, Texas, July 24th, 1998 -- The Metals Group of the Advanced Affordability Initiative at Lockheed Martin Tactical Aircraft Systems has been evaluating a process to reduce airframe assembly costs, and the early prognosis is good…
…Preliminary cost estimates indicate a savings of 15 to 20 percent over current processes. …
…In addition to the cost savings, investment casting also improves quality because unitized construction can eliminate potential fatigue problems associated with the numerous fastener holes required for assembling detail parts. Moreover, the designer can create shapes that are normally very difficult or impossible to machine. Shapes of this type improve load distribution and ultimate strength.
It used to be the case that cast components in aircraft had to be spec’d with a built in fudge factor on strength, because they were thought to be less strong and reliable (and back then, probably were). That factor is rapidly becoming a thing of the past as it is recognised that a sound casting can indeed be just as strong as a forged one or a fabrication.
As well as being as strong, castings can be developed more quickly and at less cost. They can also be produced with such features as coolant ducting, which can’t easily be done with other techniques, and complex shapes can be produced in one piece saving enormously on assembly time and warehousing complexity. That is why they are forming more and more of the structure of modern aircraft, as well of course as the major components of their engines. Just ask Boeing and Lockeed
In AR15s - search AR15.com, you will find several threads on cracked/broken cast recievers and almost none on forged/billet. I know cast is good enough for 99% of civi use but in this case facts are facts - cast is weaker.
I would be surprised if it was solely due to the fact they were cast. As I said earlier, it is perfectly possible to make bad receivers by either casting or forging. Witness the fact that well over a million Springfield 1903 models had heat treatment problems which led to a number of failures and to these low-number receivers being considered less than safe. That doesn’t mean forging is a bad technique, and nor does the alleged failure of some unquantified number of AR15 knock-offs. Can you point to what aspect of their failure is attributable to being cast, and not to poor heat treatment, poor quality control or other factors?
In swords - a hammer forged blade will be stronger than cast one. Yes they both need to be heat treated but the fact remains.
In knives - good ones use steel that is rolled into sheets by high pressure rollers, just like forging uses high pressure blows to shape a product. Of course heat treating is the heart of the blade but a casting will not be as strong as rolled/forged steel.
I doubt that anyone has tried making swords by modern casting methods, but there are indeed knives being made that way, and the best of them have some very good properties. Strength is of course only one property of a good knife. Certain cast cobalt alloys have good strength coupled with excellent wear resistance, good cutting properties and good corrosion resistance. There are also high end cast stainless knives such as the Boye “Dendritic Steel”, as well as more prosaic but also more widespread applications such as surgical blades, shears and so on which are well proven.
Yes, there are different alloys and you can change sizes but with all things equal (same alloy/heat treating/size) forged will always be stronger than cast.
No longer necessarily true, and there are other advantages one process might have over the other including not only the physical properties of the finished article, but time to market, development and tooling and production costs, and even whether you can make it that way at all.
Getting back to rifles though, the well-proven reality is that investment casting is being used, much more widely than just by Ruger. Browning, Sako, Miroku and many others are also using this technique. With proper heat treatment and QA it is well proven as a means of making sound receivers and other firearm parts, just as with proper heat treating and QA forging can be used, or machining from bar or seamless tube stock. There is no longer any technical reason why a receiver made by one method or another, all else being equal, should be any less reliable or durable than another.
