metal strength

[Anonymous No.1060235]

What is stronger?

[Anonymous No.1060236]

>>1060235
I really don't think steel. Or crystals work like that... But I have been wrong before.

[Anonymous No.1060238]

>>1060236
>But I have been wrong before.
And you're wrong now.

[Anonymous No.1060243]

>>1060236
yeah, you're wrong meow
think of steel grain like what happens when you pull or mold silly putty. you can see the grain. when it cools it becomes like the grain of wood.

>>1060235
my money is on forging, but thats a pain in the ass to do on a piece like this.
the piece is much more easily made by casting (inferior) or machining (usable for non-impact or y axis compression)

[Anonymous No.1060252]

>>1060235
where is this question coming from? what context? strength against what? although i would bet in almost all circumstances a forged part will be stronger if it is the same material

[Anonymous No.1060256]

>>1060235
Forged, obviously.

Machining is better for dimensional accuracy, though. Both have their place.

[Anonymous No.1060264]

>>1060235

if forged/machined from stock and put straight to use, forged would be stronger due to work hardening and preservation of existing grain structure to the part's geometry.

if heat treated before use, the internal stresses and grain structures will both be "reset", so both parts would have the same strength

forging is more economical since theres little scrap or material waste, while machining often has lower tooling costs and more flexibility. which method you use typically depends on other project constraints more than material strength

[Anonymous No.1060266]

>>1060264
He knows what is up.
Totally depends on structure, and material composite.
Another big factor is hardening

[Anonymous No.1060269]

>>1060235
Why not machine a forged part?

[Anonymous No.1060270]

>>1060269
The austenite, rest austenite and martensite will deform the product. The outer part hold the inner martensite(which is unstable) in position. If you remove the outer part, it's like the metal roster will seek a new structure. Thus deform

[Anonymous No.1060271]

this entirely depends on the use and shape.

a sword or knifeblade? makes no difference - the blade was forged to shape in rolling mills to get grain before it was worked to shape, as a fundamentally straight bar, its not making any changes really.

a Z shaped crankshaft? or a Y shaped piston conrod? Then it makes a difference.

[Anonymous No.1060277]

>>1060271
what about swords forged from a steel folded over a thousand times?

[Anonymous No.1060278]

>>1060277
fuck off

[Anonymous No.1060282]

>>1060277

the japs didn't fold it a thousand times in the name of craftsmanship, jap iron was so diluted with other minerals they HAD to fold it over and over to work the garbage out of it because they were to lazy/arrogant/stupid/poor to purify the metals while they were molten, and perfect the metal before working it

[Anonymous No.1060293]

>>1060256
what if you forge the part and then machine it to spec?

[Anonymous No.1060295]

>>1060235
depends on how it's being loaded.

[Anonymous No.1060299]

If it wasn't milled from a perfect crystal. The forged one is always stronger. Forging creates little imperfections in the crystalline structure, which make it harder to deform.

[Anonymous No.1060327]

>>1060235
well thats not actually how the grain structures appear... but the correct, albeit boring answer is that it depends on the processing.

have the parts been heat treated? this will affect the grain structure and other defects. forging generally produces work hardening as the crystal is deformed, whereas machining produces a comparatively minor amount of tool hardening.

Interestingly enough, if you had a single crystal bar, you would have significantly less of the problems with grain boundary defects like creep, but you would get no benefit from work hardening techniques

[Anonymous No.1060338]

>>1060282
Pretty much this.

If we are talking about Wootz steel on the other hand.... holy shit that crap was good.

Those poo in loos really knew their shit when it came to metals before the 17th century.

[Anonymous No.1060345]

>>1060327
This. Good grain structure improves ultimate tensile strength, but doesn't produce hardness unless you're specifically using hardening alloys and get the correct phase for the solid solution.

[Anonymous No.1060347]

>>1060338
Fun fact: there is no evidence for wootz steel or damascus steel being anything but pretty crafting

[Anonymous No.1060366]

>>1060282
>the japs didn't fold it a thousand times in the name of craftsmanship, jap iron was so diluted with other minerals they HAD to fold it over and over to work the garbage out of it
Half-truths and confusion. A traditionally-forged, pattern-welded Japanese blade (the method was used for any quality blade, including knives and spearpoints, not just katanas) isn't folded "a thousand times" at all. It gets folded a few times, and each folding doubles the number of layers, resulting in thousands of layers.

Any traditional wrought iron sponge, or carbon steel produced by related methods, needed the slag beaten out of it, and European swords (as well as earlier Japanese swords, before they developed this method) were made entirely from this (until advanced crucible steel methods were developed).

Traditional Japanese blades take advantage of the labor-efficiency of using cheap, easy-to-produce cast iron, a technology unknown in the West until much later. It's quite a clever method, and could be used to produce either very high quality or a quantity of reasonably affordable blades, depending on the care taken in selecting and working the metal. Cast iron on its own was used for lower-quality tools (like the "ninja knife" you see in popular culture, which in reality was essentially a garden trowel used primarily for rooting out stubborn weeds, and was canonized as a ninja weapon from the notion that it could be carried with plausible excuses -- the "throwing star" is also based on a carpenter's pocket tool for prying nails).

They are still in demand, in part for their quality (old tech can be good tech, especially in an area that was of central importance in the past and became largely unimportant in the modern era, like long blades), but mostly out of love for the craftsmanship, tradition, and aesthetics.

[Anonymous No.1060370]

GE is working on 3D-printing nickel alloy fan blades for their jet engines. I'm curious how long until those show up in an engine

[Anonymous No.1060441]

>>1060370
That sounds really hard to do, but really cool! How would they keep the monocrystal from forming new grains as they print metal onto it?

[Anonymous No.1060442]

>2016
>Metal forging

You're on borrowed time.

[Anonymous No.1060446]

>>1060370
Boron Nitride will be the next big thing for strong high temperature composites

[Anonymous No.1060451]

> not growing single crystal parts every time

Casuals

[Anonymous No.1060453]

>>1060446
> next big thing

Cubic boron nitride has been industry standard for high quality cutting bits since the 60s

[Anonymous No.1060456]

>>1060453
not cubic, boron nitride nanotubes and sheets

[Anonymous No.1060463]

Modern steel doesn't have "grain". It's not like wood and is homogeneous and free of impurities.

They would be of equivalent strength.

[Anonymous No.1060482]

>>1060442
Plenty of stuff is still forged. A lot of industrial chain links are forged, and there are millions upon millions of those in use all over the world.

[Anonymous No.1060490]

>>1060293
>^ bumping for this question. My guess is that would provide the best of both worlds. Not an expert on it though.

[Anonymous No.1060507]

>>1060269
That is often how it is done. Many parts are forged or cast first to get the rough shape correct (neither are particularly precision in the realm of things) and later the critical dimensions machined to a finish (or sometimes, machined all around).

>>1060270
True, but there are machining strategies to reduce the chance of this happening, and also parts can be straightened. At work, parts can be held relatively straight by machining both sides, thus relieving the stress relatively evenly. Other than that, we also have a straightening department where the parts are returned to straightness via hydraulic press. Lastly, skilled shot peen operators can straighten out a part by concentrating their efforts on certain areas of the part. You can move the part a surprising amount by this method.

Every piece of metal is different as far as internal stresses. Even a rolled plate or bar can be quite different. Different amounts of distortion can result as well if you generate a lot of heat in your machining process (for example, using a duller tool, or cranking up your spindle speed without increasing chip size or inadequate coolant).

[Anonymous No.1060521]

>>1060293
forge manufacturing engineer here. This is what happens to pretty much everything; forge the part, machine away excess.

[Anonymous No.1060525]

>>1060521
machinist here. This is what happens to pretty much everything; forge the part, machine away excess.

[Anonymous No.1060635]

>>1060442
Own a car?

Most likely the crankshaft and connecting rods are forged. This isn't likely to change anytime soon until EVs fully take over.

[Anonymous No.1060646]

>>1060635
Some, not all.

>>1060482
Much of this is being replaced by automation. While in the sense it is still hot metal, it's not being done by hand.

[Anonymous No.1060663]

>>1060441
I haven't looked into it, but presumably they're going with microcrystalline or semi-vitreous structures instead of monocrystals.

[Anonymous No.1060664]

>>1060635
Not true my friend. Forged remains to be limited to the performance/heavy duty market. There is little to no benefit to putting forged parts in a daily putter.

[Anonymous No.1060756]

>>1060235
I don't really know much, but let it be said that performance car engines use forged pistons because normal ones are too weak for the job. So, at least in this single case, forged is better.

[Anonymous No.1060765]

>>1060264
>forging is more economical since theres little scrap or material waste

No, typically because of forging die costs. Materials are trivially cheap. That's one reason casting preceded forging for so many parts and a key reason most machine shops had foundry capability until the 1940s at least.

[Anonymous No.1060889]

>>1060756
Most of the reduced strength that comes with casting comes from the porosity and disturbed grain structure of the final part. It really depends on how much they want to spend on reducing gases in the melt, which can be a very toxic and nasty business (not to mention expensive) to complete.

Forging is a somewhat more straight forward process, it seems. It's easy to pour a bucket of liquid metal into a cup, but you aren't going to like what you get when it cools.

[Anonymous No.1060954]

>>1060269
It is often done. However, you have to anneal it first because the forging process creates inner constraints within the metal part, and while they cancel each other as it is, as soon as you start removing metal the balance is broken and your part will deform. So yeah, forged part are usually stronger (still depends on the kind of constraint you're submitting it to) but you don't get really far with them without machining them.
It still saves a lot of material compared to machining it all from a block, and even after annealing you can retain structural strength from the process.

[Anonymous No.1060957]

>>1060765
Doesn't the scale of the series influence the price though? I would have thought that forging would be more time efficient than molding or machining for large series.

[Anonymous No.1060969]

>>1060451
What is this fuckery? That's the first time I've heard of it.
Seems pretty hot desu

[Anonymous No.1061012]

>>1060969
It's what they do for turbine blades and silicon wafers

If you look up the thread on large bismuth crystals I posted a couple more pages on that

[Anonymous No.1061025]

>>1060969
>>1061012
They do it for optics materials too like sapphire and germanium

[Anonymous No.1061095]

>>1061025
Yup, though with sapphire they do it a bit differently and it often involves very high pressure
>>1060969
Just realized that bismuth thread is archived
Here:
>>1056032

[Anonymous No.1061108]

>>1060765
>>1060957
notice i said that machining has lower tooling costs, because of the high initial cost of die making.

for large-scale or low-tolerance production runs, forging is more economical because the die costs and rapid rate of production undercut the cost of machinist labor and scrap removal/recycling.

although that might be changing with modern increases in cnc production. i only have experience in smaller machine shops so i cant say exactly how much costs scale up in industrial settings, but most commercial products are cast/forged and only machined if tighter tolerances are needed

[Anonymous No.1061120]

>>1061012
we make magneto cooling crystals using the high temp bridgman process. pretty common actually

[Anonymous No.1061171]

>>1060756
This was maybe true fifty years ago. Wake up billy, nowadays it's done with diamond coatings. This makes it possible to increase preasure like a 100x times. And makes the material 1000x stronger (maybe slightly too optimistic)

[Anonymous No.1061175]

>>1060969
This is true, but if you Keep the proces going you will get enormous crystals thus easily Break. But if you cool and heat a little then heat again, and so on. This will create many smaller crystals

[Anonymous No.1061407]

>>1061175
Are you an idiot?

The objective is one giant giving Crystal

A single crystal is significantly stronger than any columner or equiaxed material

You shouldn't talk about things you know nothing about

There is a reason they do this for turbine blades, and that is because it is the only way to keep the entire fucking turbine from being torn to shreds by even slight variations in material strength

[Anonymous No.1061410]

>>1061407
Fucking not giving

[Anonymous No.1061441]

>>1061407
That's not true, they use nickel single crystal alloys for turbine blades because they were having problems with turbine blades that were plenty strong, but had an unfortunate tendency to elongate when placed under outward load at a high temperature for a long period of time. Technical folks call this "creep".

Eventually the blades realized their lifelong dream, caught the edges of the turbines and sent it through the fucking wood chipper. >Big mess.

Single crystals handle creep elongation much better, and they've been using those since. It's a damn shame though because they are ungodly expensive and add significantly to the cost of the turbine.

[Anonymous No.1061442]

>>1061441
pic related

[Anonymous No.1062268]

>>1061012
link?

[Anonymous No.1062377]

>>1061441
so cast iron, machined, forged?

[Anonymous No.1062408]

steel isn't strong, boy. flesh is stronger.

https://www.youtube.com/watch?v=P2EQ0FlVks4

[Anonymous No.1062433]

>>1062268
See
>>1061095

[Anonymous No.1062463]

>>1062377
are ya talking about the picture? From the left its probably: cast with heat treatment

And then the directionally solidified and single crystal are typically variations of a sort of simple concept but fucking very hard to put into practice method. Basically
>put chunk of oriented "seed" crystal of the same metal on a water cooled crucible
>on top of that put a really fucking hot melt crucible with a hole in the bottom and melt down your metal
>slowly pour the liquidus onto the chilled seed
>metal crystallizes into same orientation of seed
>pass Go, collect $200

The single is a lot harder because you need to ensure that there is only one grain that influences the final crystal. So they basically use a really twisty tube (think of a duck vagina) that goes down to the chosen small seed and then when the liquidus contacts the cool seed it crystallizes the whole thing into that orientation.

Pretty cool, but a real strong pain in the ass if you want production quantity at a decent cost. There's a lot of government into "high entropy alloys" that can hopefully do the same thing but they are much simpler to produce.
>hopefully because if they dont its back to welding for this guy

[Anonymous No.1063028]

>>1062408
...That guy has a very punchable face

[Anonymous No.1063037]

>>1062463
duck vagina

[Anonymous No.1063085]

>>1063028
Whaaa Darth Vader is awesome

[Anonymous No.1063190]

>>1060525
Industrial engineer here, I don't work with metal but what these guys are saying sounds legit.

[Anonymous No.1063224]

i need to get the last nut off of a slightly bent bicycle axle.
do i need to buy a vise-grip pipe wrench?

[Anonymous No.1063238]

>>1063224
That or put the axle into a vise or heat up the nut with a torch. Make sure it has a thick coating of grease and oil before to make sure the flames get good penetration

[Anonymous No.1063240]

>>1063238
don't have any of this. i'd plan on buying a vise grip pipe wrench. <---- so if i get this will the axle turn in it's grip or will it be a super strong hold?

[Anonymous No.1063242]

>>1063190
thanks for the support engineerbro. I had another fun filled night shift forging parts of all shapes and sizes.

Are there any other questions about forging? This video shows the machining that's done to a forging to make a part, this is typical of every part we make. And don't ask me about heat treating, it's something that goes on in a dark corner of the building that I want nothing to do with. That and company secrets and shit.

https://www.youtube.com/watch?v=B7ArUqpgeHk

[Anonymous No.1063273]

>>1063240
Just use a normal vise grip on the axle

[Anonymous No.1063277]

>>1063242
Thats awesome. What are the limitations of forging for complexity of parts??

[Anonymous No.1063319]

>>1060525

Machined something that has already been forged? Really? I thought it was just grinding and polishing.

[Anonymous No.1063508]

>>1063277
Not much, just size really, but you can make some really huge open die forgings like ship driveshafts or big columns or shafts for machines.

[Anonymous No.1063548]

>>1063508
can you make me a nozzle bell?

[Anonymous No.1063662]

>>1060370
3D printing new blade edges onto worn blackhawk turbine rotors has been going on for a while.

[Anonymous No.1063716]

>>1063548
If you want to spend several hundred thousand $$ on dies, yes. We've made hemispheres like the ones in the link.

https://www.whoi.edu/page.do?pid=8422&tid=282&cid=53066

[Anonymous No.1063811]

>>1060451
Name of the book? Seems like it's not pre WWII (not always shit but often bad scans)

[Anonymous No.1063827]

>>1063811
Manufacturing Engineering & Technology (6th Edition) https://www.amazon.com/dp/0136081681/ref=cm_sw_r_cp_apa_Jfa8xb7CTG87Z

It is an absoluty amazing book

I highly suggest it, it was one of the few books I kept after graduation

[Anonymous No.1064497]

>>1060238
You obviously have no idea what you're talking about.

[Anonymous No.1064668]

>>1064497
what exactly are you talking about? That's how grain structure works in forging.

[Anonymous No.1064819]

Forging ofcourse faggot