Might be a dumb question. Etch process we use to check grind parts for burn. Is dip in cleaner which might just be water. Then we dip in hot water to heat metal then acid then cold water to cool then some kind of rust preventative. Then we blow part off then check surface for burn. Now my question is let's say that the part has a dark spot that indicates burn. I rub my finger over the dark spot and it goes away and then that spot looks like rest of tooth. Was that spot actually burn or just dirt?

Hi! I'm looking to expand my knowledge beyond steels, which is what I have primarily worked with in the past. If anyone has recommendations for some introductory books which cover the topics of Titanium, Aluminum, Magnesium, etc. I would highly appreciate that. Preferably available for purchase in physical media at a decent price.

Thanks!

I bought an Ofyr grill for our beach property four years ago (same as depicted in the picture, and yes, the delights that are created on that thing are even better than in this picture). The base and supporting cone are made of regular run of the mill steel. The grill top is carbon steel. Well, after four years of punishing salt air, the base and supporting cone are destroyed and dangerous. We always kept the whole unit covered by a thick vinyl cover to help protect it, but alas, Mother Nature did her job.

So, the carbon grill top is in tip top shape. Thus I am going to fabricate a new base and cone (there’s a small machine shop where I work, so we can fabricate just about anything minus rolling being involved-I’ll outsource that for the cone). It’s a processing plant, so we’ve got lots of stainless steel experience.

Crossroads: 1). I can just copy everything as is and replace again in four years, but it’s not as easy as it sounds. The only option is to fabricate given where I live. So every four years is to be avoided if possible. Or, I can try to figure out another form of rust prevention in attempt to extend the life of the standard materials, despite our brutal onshore winds. Advice on this one, please. The thing heats up so much that any oil or what not seems to burn off or get messy. And I can’t access the interior well, so if a regular grease down will take care of it, I’m not able to apply as the carbon steel grill ring is too heavy to move on my own in order to access the interior of the base.

2). I’d like to fabricate the base and supporting cone out of stainless steel and then rest the original carbon steel grill top on top of the stainless base, but am worried about galvanic corrosion where they meet. Please share advice on if this plan would work and what to be on the look out for or how best to approach it if I do go down this path. I’ve looked up grilling and stainless steel firewood pits and have found helpful info that convinced me there won’t be any toxins released from the stainless steel cone. But the combo of the carbon steel ring on the cone gives me a little pause given my ignorance of chemistry mixed with it being heated to ~500F / 260C.

Let me know what you all think is the best approach! A man’s gotta eat.

Making a DnD setting, built on top of some millions of year old ruins of advanced precursor civilization that had access to pretty much the entire periodic table of elements. Drawing raw material from those ancient resources, what might some medieval-esque high fantasy folk get up to with those rare earth metals?

And/or, if this is a dumb question since I'm nowhere near an expert on this, what sorts of questions should I be asking instead?

Some bismuth crystals are cubic hoppers and some are more like dendritic branches; I want to be able to influence which type grows. Is it possible to control the structure of bismuth crystals by adding impurities to a bismuth melt?  Literature suggests increasing interface instability leads to dendritic growth instead of hopper. How can I do that?

I don't understand crystal growth well enough to tell if I should remove impurities, or add impurities, or which metals to add and in what quantities.

Are impurities even the right way to control structure type? I've grown hopper and dendritic crystals from the same batch of material on subsequent melts without knowingly changing the composition, which makes me doubt that impurities control structure. How else can I control crystal structure? 

Hi everyone, I'm looking to electropolish a stainless steel 316 product. Currently facing issues where the product develops a tea stain like effect and sometimes red rust as well.

Usually happens if exposed to a decent amount of rain and moisture. But since SS 316 is supposed to be more durable to rust, am looking at electropolishing to make sure the surface is free of impurities.

Shared photos of the issue: https://cubeupload.com/im/Temporalator/Screenshot2024120319.jpg

https://cubeupload.com/im/Temporalator/e6aScreenshot2024120319.jpg

If anyone can guide me on how to electropolish ss 316, it would be greatly appreciated. Thanks a lot everyone.

Superior in terms of durability, edge retention, balanced hardness, and flexibility, and it isn't too heavy without being brittle.

I am planning on making a heat recovery ventilator with the primary heat transfer being Aluminum foil, the foil will be suspended by other materials so strength isn't really necessary, although this foil will be in a likely wet environment, and be exposed to the air, so I am curious on how thick it needs to be to last a descent measure of time, at least around 10 to 20 years or so. Most HRVs are made with aluminum foil at is around .12 to .18 mm in thickness, as far as I can see online, although I believe it is due to that HRV cores structurally support themselves. How thin can aluminum foil be in this environment to last a descent amount of time. the thickest I can seem to find is around 40 microns, or .04mm would that be enough?

So a few years ago I bought some brass powder that I was going to mix with an epoxy to "cold cast" with. I never ended up doing that though, and now I have a small electric furnace I've been using to melt copper and tin grain with. I'm running low on metal, and don't have any money to buy more with at the moment, so I was wondering if I could just fill my crucible with the metal dust I had bought for cold casting, melt it down to a liquid, and pour ingots with that for later use. I was just a little worried that heating up such fine dust might have some kind of dangerous reaction like a flour bomb or something.

In the world of combat robotics every team is always looking for harder and stronger metals for armor and weapons.

I've used watercut AR500 for some builds but was wondering if shot peening would increase the impact performance.

Alternatively if anyone has any other ideas for harder metals that can withstand large impact forces I'm all ears.

I want to do pistol frames that have a Damascus steel type pattern but made from softer metals to make it easier to machine. If I could work copper in there as well it would be a bonus. Any ideas?

I was wondering if I could make little figurines etc in my oven by mixing tin powder with copper or brass? Perhaps with some flux if that would help get things flowing?

I am a bit worried about fumes etc, so maybe I should get a tiny oven and do it on my balcony, which is why I cant get any type of smelter, I live in an apartment.

My idea was to make a hollow (negative?) mold out of plaster, fill it with some ratio mixture of copper + tin or brass + tin powder and "cook" it in the oven at 240C since tin is supposed to melt at ~230C for X time and then let it cool before removing the mold.

My current concerns are

1. Fumes while cooking the thing
2. That the tin wont melt / re-flow at domestic oven temps, especially when mixed with copper or brass
3. That the plaster mold will react with the metals in some way
4. Expansion during cooking leading to overflowing / cracking of the mold
5. Shrinkage after cooking, but since the copper or brass should not melt that shouldn't be a big issue right?

The powders I found during a quick search was was these:

Tin:

• 45 µm
• (Pb) : 0.001% Max
• (Cu) : 0.003% Max
• (Al) : 0.001% Max
• (Cd) : 0.001 % Max
• (Bi) : 0.001% Max

Copper:

• 45 µm
• (Al) : 0.004% Max
• (Cd) : 0.001 % Max
• (Pb) : 0.001% Max

Brass:

• 45 µm
• (Cu) : 70%
• (Zn) : 30%

Would other metals work? Something like silver, or iron? Something that would be safe to wear on your skin? If not would it be possible to electroplate a metal that would be safe on to it and make it safe that way?

If I can do this I will of course use a mask while handling the powders, would one of my old covid n95 masks be good enough or do I need something else?

This got way longer than I expected, I really appreciate any help as I really think it would be cool to make stuff out of metals even if I can not operate any type of forge, thanks for reading.

Our customer (wind turbine manufacturer) wants us to provide them with tin Bronze bearing bushings (Cu-12Sn-2Ni) with >8% elongation (in tension).

The best we could achieve is 5%.

We meet their yield strength (>180 Mpa) and tensile (>300mpa) requirements. But the >8% elongation target seems unreachable.

We employ centrifugal castings to fabricate these bushings. Generally, as tensile strength increases, so does elongation (unless you're dealing with metal-matrix composites with weird microstructures). We tried to increase the cooling rate by increasing spin speed and reducing pouring temperatures. So the microstructure may be refined, improving tensile strength and elongation. But we're at the limits of our machine capability, so the spin speed could not be increased further.

What other ways can we improve the elongation? Few ideas I had...

1. Increase phosphorous level to the maximum permissible amount (0.4 wt.%): Primary phosphide phases may act as nucleation zones for alpha-Cu grains. Increasing nucleation rate, thereby refining the microstructure

2. Inoculation: I could not find much info about inoculation of Cu-Sn alloys. I've tried the ASM handbook. They mention inocculation is used in tin-bronze, but didn't mention what those were! I saw a master's thesis claim rare earth elements like Zirconium and boron, can increase the nucleation rate.

3. Heat treatment?

Would be interested to hear your ideas!

Thanks

Given stainless steel inserts, what metal can I choose for the bolt to avoid galling?

Forces involved are not very high, but there is some vibration.

I'm in the UK. I can buy bolts in mild steel with bright zinc plate (BZP), hi-tensile steel, or stainless, which is usually going to be either 303 or A2. I can find brass, but only in slotted or pozi, so that's not a great option. I do not have access to a lathe - what I can use is what I can buy.

Backstory:

I mounted the bindings on my skis last season with threaded inserts, to make them removable. (Standard practice is to screw straight into the ski and avoid disturbing the fitting if possible.) I carry all my gear on my back through London and Paris, and it's horrible with the bindings mounted.

I selected stainless due to the wet environment. The inserts were sold as 303 and the bolts as A2. They do look correct to my amateur eye.

I used plentiful quantities of grease to avoid galling, but of course one of them did gall, and I now have a bastard of a job ahead of me.

Ideally, I'd leave the other inserts in place. My skis have a poplar core; it does not hold a thread well. Now that they are in, I'd prefer not to disturb them. However, if the sub decrees that I must, I will change them.

I don't care if the bolts rust, I can replace them. But I really can't have them galling again. They absolutely must come out without heat.

I assume you guys get this alot, but i want to dip my toes into metalurgy. The thing i want to learn the most about is the different types of steel, alluminium, brass and bronze alloys and all their properties. I am into machining and blacksmithing (as hobbies) and would like a better idea of what types of metals to choose for projects. Any source or guidance would be appreciated

I am trying to determine if a part supplier is jerking my chain.

I spec'd 17-4 H900 and the part came in silver. It would appear to me that the part is still in a 17-4 annealed state but they claim their stock material it was machined from is 17-4 H900.

The aluminum structure is a walkway platform installed near the CL49 totes (500 gal) to allow personnel to inspect the valves; the chemical leaves at the top of the totes through the valves only. So, the chances of a spill are very low, but there are still concerns because of the Al - NaOH high reactivity. NaOH is one of the components of CL49.

This microbiocide chemical has a 13.6 pH and is stored in ambient conditions. The area where the platform and the totes are is inspected during daily walks. This is an industrial space and removal & reinstallation of the walkway is not an option due to added cost and operations disruption.

What are some mitigation solutions in the case of a CL49 chemical spill contacting the aluminum walkway structure?

I'm reading about protective coatings, such as paint, lacquer, or clear sealants, to create a barrier between the aluminum and the surrounding environment. But is there any coating to protect against such a corrosive chemical? If yes, can you recommend some name brands/specific products?

CL49 SDS: https://tinyurl.com/yfrmudwd

I'm hoping someone can help me identify a name/characterization for this surface of an internal void. The first thing that popped into my head when I saw it was a handful of uncooked spaghetti noodles.

Also if anyone knows what would cause this kind of surface/structure, please share with me!

https://preview.redd.it/f6l3p4fl743e1.jpg?width=2048&format=pjpg&auto=webp&s=b862768ddc61f2f88129ac14f2423cbaecb2e198

https://preview.redd.it/o8vdu5fl743e1.jpg?width=2048&format=pjpg&auto=webp&s=a4b45d07c07a2a92450f5b3d9e9743a8abf028c3

I'm thinking about making a chainmail bracelet with silver rings and bronze rings. Do those metals react with each other? Do they have any negative interactions?

Just in case my meaning isn't clear, I'm asking in the same vein as how brass causes a rapid corrosion of the zinc in galvanized steel when in a moist environment.

So pictured a very basic phase diagram for Au & Ag alloys.

How is this shown in a diagram if say, you have an alloy of Au, Ag, & Cu?

Am i missing something? (Perhaps we just not have got to that in class)

Big noob here, please forgive me.

Hello everyone. I’m sorry to bother you, but I was wondering if you could help me with my unusual dilemma. I want to get rid of a stainless steel keyring. I’ve read that this metal lasts a very long time. I can’t recycle it in my local area, and I can’t donate it.

This is because it has a highly personal inscription on it. It was sent as attempt to manipulate me before the sender ended their own life. It is a very painful thing to hold onto. After a year, I’ve decided it needs to go.

I don’t have access to a lab - is there something I can do to accelerate it breaking down at home or destroy the etching? Maybe leave it in a jar of bleach for a while before trashing it or burying it somewhere?

I would be very grateful for some advice, even if there is nothing I can do. Thank you for your time.

Edit: Thank you for your help internet friends. I wasn’t sure what would be safe. I have finally taken this metaphorical albatross from around my neck; and finally feel light again.

Your mentally ill mother committing suicide, and lashing out at you one last time is a difficult thing to have to deal with. I put off the heaviness of this item whilst I had to make arrangements and wind up her estate. As I have ended therapy, I knew I needed to get rid of this thing and your help was very much appreciated in deciding how.

Just out of curiosity, what resources are there to see/learn about the average relative prices between Aluminium alloy families and within families in general? I imagine the price difference to be minimal (and irrelevant for my consumption), but I still wonder how they differ.

Thank you for any insight!

I’m doing some lab-scale quenching tests for steel. I have a small muffle furnace which has the option to accept (inert) gas flow. I did some initial tests on some samples of 1018 low carbon steel to test quench capabilities of a certain quenchant. Samples were 25mm in diameter and 25mm long.

After I was finished, samples prepped, the surface hardness was pretty poor. You could actually see a parabolic-like gradient in the hardness-depth profile peaking at about 1mm deep. Hardness was ~250 HV at the surface and ~350 HV (maximum) at 1mm depth.

I think it’s pretty clear that there’s some oxidation and decarburization (as you can see from my low quality micrograph,) and I’m wondering what I can do to lessen this and keep high hardness at the surface. I’m currently trying to get an inert hooked up to give a crude purge in the furnace.

Any other ideas?

I cleaned my stainless steel watch with peroxide. I wiped it with a peroxide on a cloth and then i put it on my wrist. It was very brief. Now i have heard that it causes stainless steel to corode. Was that enough exposure and how much does it take for it to corode.

So like for example, I'm melting some tin, which becomes liquid at 449.5F. I was planning on pouring it into a plaster investment mold preheated to around the same temp. Tin boils at 4716F, and if it got that hot, I assume I would start losing metal since it would become vapor. Could I however raise the temp to like 600F so that It stays hot longer and can be poured into my mold without solidifying as quickly, or would that have adverse effects?

Hello Metalurgists -

I finally cleaned out the filter in my clothes washing machine, but that's s story for r/appliancerrepair. And I found the following -

https://preview.redd.it/ywbkpl9wp92e1.jpg?width=3494&format=pjpg&auto=webp&s=a87137f45d66a3f8a4500b9953d7f940dadd72a3

https://preview.redd.it/umig8m9wp92e1.jpg?width=3637&format=pjpg&auto=webp&s=cff30380b877380f0103650245765d3bd7e1ac26

What the hell could have corroded those pennies? I've put a modest amount of chlorine bleach through the washer. Also vinegar, OxyClean, detergent. I live in NYC where the water is said to be very good for a public water supply. Your thoughts?