/r/metallurgy

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Discussions on metallurgy. Links to the popular press, scholarly works, personal blogs/websites, and general discussion are welcome and encouraged!

Please refer any literature requests to /r/scholar unless the author is present on this subreddit.

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/r/metallurgy

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3

High Iron content steels?

I'm looking for a steel grade that has the highest iron content possible while still maintaining a decent amount of strength, and corrosion resistance. I guess this would mean I'm looking for a low alloy steel?

Ideally I would like at least 99.8% iron, but based on what I've seen I don't think this is possible?

29 Comments
2024/05/20
13:05 UTC

22

Microstructure in Martempering

Can anyone tell me what will be the microstructure at this point in martempering?

9 Comments
2024/05/19
13:48 UTC

2

Is there any books or podcasts I can research to learn from first hand accounts of the mining of certain metals?

Im currently developing a system of psychology using and building upon a gentlemans previous work named Carl Jung. It's heavily influenced by metals. Particularly Gold, Silver, Tin, Lead, Mercury, and iron. I would like to learn more about the mining process, possibly from the older accounts before large machines or tech has been implemented. But modern information would be greatly appreciated. I know this question is probably different from what you accustomed to but this project working on has the potential to help people even if it's a small amount. So and books, pods or references would be greatly appreciated in the process of mineing of said metals. Also any inside baseball frist hand knowledge you have could also be helpful. Thank you for your time.

8 Comments
2024/05/18
15:12 UTC

4

Revealing Inconel 625 Microstructure

I have two pieces of Inconel 625 that have been spot welded together but I have had one heck of a time trying to etch it to revel the weld itself and the HAZ. The old reliable HCl + H2O2 does not even touch this particular sample and need some suggestions for other echants and techniques to use. I have tried to etch it right after polishing with 1μm diamond suspension to minimize the formation of a passive layer. Glycergia, acetic Glycergia, waterless Kalling's has not worked either. The best luck I have had was with Lucas Reagent but it was mediocre at best. This alloy is just really good at what it's supposed to do, being corrosion resistant!

12 Comments
2024/05/18
03:29 UTC

5

Can silver/gold acid tests make you sick/poison you?

Last night I got really sick feeling, really nauseous, burping a lot, almost vomiting. But it also seemed like I was having an anxiety attack and I was tossing and turning all night with bizarre thoughts. Today I feel super weak and my body hurts.

But I didn't eat anything unusual.

The only thing I can think of is that I was fucking around with 18k gold testing acid and whatever the silver testing liquid is that turns red in the presence of silver. I had the windows open. I'm pretty sure I didn't get any on me, but I might have breathed in some fumes. I wasn't being that careful. At the same time, I didn't notice myself breathing in fumes.

I'm getting all paranoid thinking I might have inhaled heavy metal vapors or something. I know nothing about this. I bought the kit on Amazon. It's probably not this, but I've never experienced feeling sick like this. Usually it's more obvious if you have food poisoning.

11 Comments
2024/05/17
22:01 UTC

0

Are any copper alloys suitable for making rings?

Excluding copper+gold.

Maybe copper alloyed with tungsten or platinum/palladium would be tarnish resistant and still have a coppery color?

8 Comments
2024/05/17
10:21 UTC

0

How can one identify inclusions or pitting in steel using 6% nital?

1 Comment
2024/05/17
00:00 UTC

2

Internship for metallurgy or materials Engineering in India

Currently i am a third year B-tech student in Metallurgy and Materials Engineering. Where can i do 4 weeks internship in Metallurgy or materials engineering offline ?

0 Comments
2024/05/16
13:03 UTC

6

Dark residue on certified 304 steel, passivation.

I apologize for this Q being long. I have previously asked this on metalworking and chemistry forums, and have so far found no solution. TLDR: I have a custom-made 304 steel part which appears to be not "stainless". There is no "rust" on it per se, but it leaves a dark-grey residue when rubbed with a clean scientific-grade filter paper. I have never experienced this with mass-produced 304 steel parts which I have used before, and I am looking for ideas on how to turn the 304 part "stainless".

The long story. I have a custom-made air humidification tray welded of 1.2 mm thick 304 steel (supplier: Aperam, France, with certificates of analysis). The tray is used in a medical device prototype: in it, the tray is filled with about 5 gal of warm di or tap water (at ~100F or 38C), and air is blown between the water surface and a sealed acrylic lid. The warmed/humidified air is then directed to a patient through a mask for direct breathing. I previously used 304 and 316 commercial sanitary parts for this air circuit, and expected the 304 steel to be a suitable material. Since no high temperatures were present, I used 304, not 316 -- 316 would double the cost.

When the tray arrived, it looked visually clean and degreased. I further rinsed it with soap and water. When I was wiping the part clean with scientific-grade kimpwipes, I noticed that the wipes turned dark grey when rubbed against the steel. This was not some grease left from the machinning/welding, because additional degreasing with acetone, EtOH or even 5% NaOH did not solve the issue -- the grey residue still remained (or got even stronger). It appeared to originate from the steel itself. As a comparison, I did the same "wet kimwipe test" with mass produced 316 and 304 sanitary parts, and these left no reside on the paper (as expected).

I then tried a passivation protocol I found in a NASA publication (link below, it's 4% citric acid for 2 hrs at 180F). TLDR: it did not help, instead it appeared to make the issue worse, as if activating the steel, but not passivating it.

https://ntrs.nasa.gov/api/citations/20110001362/downloads/20110001362.pdf

[For passivation, I first treated for 2 hrs with 5% NaOH in tap water (this turned the surface very hydrophilic). Then I filled the tray with a boiling solution of 4% citric acid in tap water, placed it in a stryrofoam box+lid for 2 hrs and monitored the temperature. The temperature went from 170F to 160F in 2.5 hrs, which IMHO was close enough to the NASA protocol. I then decanted the acid, and rinsed the tray with tap water again. The part used to have small "rusty" spots" around the welds, and now they all turned shiny which was a good sign. However, the black resuidue, revealed when I wiped the surface with a kimwipe, was still there, and it got worse.]

I do not think I can use this device before solving the dark residue issue. I do not know what the residue is, and I do not want the substance leach into water and end up in someone's lungs.

What is the black residue, and what are my options to get rid of it? Should I

-- cut my losses and have another piece made (e.g. Ti or 316, or even plastic, e.g. polycarb or acrylic).

-- passivate professionally? Judging from the complete fail of the citric acid attempt, I am not sure if it's going to work. Nitric? Nitric+galvanic? Citric?

-- electroplating? Nickel has been suggested, but it is known to cause inflammmation, thus, I am not comfortable using it. Sure 304 contains Ni, but not as much as pure Ni.

-- silver plating? That will prob require Ni and Cu first, and I am not a fan of Cu in the air, either. And course it's the cost; a Ti tray would prob be cheaper to start with.

-- powder/ceramic (enamel) coating? I have no experience with this, but I can research this further.

-- make a thick PE bag and insert it in the tray as a liner?

I apologize again for the long post.

18 Comments
2024/05/16
12:40 UTC

8

Job Searching-Metallurgist

Hello,

I am new in this group, Currently working as process metallurgist in a technology providing company. My current employment ends soon and currently they are going through cost cutting situation. So I am reaching out to other options too. I have masters in Mineral Processing. And would love to get another job in perspective field. I am residing in Finland. Could you share any valuable suggestions for me now? Finland or any other European country would have been great. Thank you so much.

8 Comments
2024/05/14
18:41 UTC

4

How are giant metal parts heat treated?

All heat treatment ovens I've seen are for smaller parts. But how do companies heat treat giant metal parts?

17 Comments
2024/05/14
07:19 UTC

5

Is it possible to make quasicrystals with rudimentary equipment?

I was wondering if it is possible to make and grow quasicrystals using only rudimentary equipment (melting furnace).

Okay, then you can make quasicrystal precipitates. Is it also possible to grow big dodecahedrical quasicrystals with rudimentary equipment?

2 Comments
2024/05/11
16:51 UTC

1

Looking for a metallurgist to make a very small sample of electric alloy

Hello, I have looked online to attempt to find a sample of electrum alloy to buy, but I cannot find much in the way of purchasing, just info about it. It is for personal interest and I would just want a very small amount, just a little bead. and the sample does not need to be extremely pure either, just as long as it is mostly gold/silver. I live in the UK, but I don't mind paying for postage if the price is right.

Apologies if this is not the right place to post this.

3 Comments
2024/05/10
19:17 UTC

1

Galvanic Corrosion Question

I am currently working on a project that will be using both 304 stainless and A36 steel. They will be pressing against each other while a steam application is being used on product between them. Will this process create galvanic corrosion? If so, what protective coating could be used?

2 Comments
2024/05/10
16:58 UTC

3

Which Metal ist this?

12 Comments
2024/05/10
16:18 UTC

5

Alloys with Sodium

I've been trying to research this for three days, and I'm about to just not do this assignment. I'm being asked to find alloys with sodium that are not liquid, soft, or volatile. Britannica claims a few metals can alloy with sodium, especially gold and platinum. The problem is finding examples. I can't find even a picture of what an alloy of platinum and sodium would look like, or even read about its uses. Wouldn't the sodium just leave it? I'm starting to wonder if this is a trick question. Thanks for any help.

7 Comments
2024/05/10
11:23 UTC

2

Looking for a stronger and more corrosion resistant bolt

Just had a bolt break off into the rear shock's axle on my ebike a few days ago now I'm looking to replace that bolt with something stronger and more corrosion resistant than the stainless steel one originally used. I like the increased strength, corrosion resistance and reduced weight offered by titanium and have been reading that it resists bonding with other metals very well but I want to know specifically if grade 5 titanium will resist bonding or reacting with the steel axle and aluminum bike frame. Thanks

10 Comments
2024/05/09
20:42 UTC

3

Are there cheap purple alloys and intermetallics?

The only alloys and intermetallics that I know are purple gold (gold aluminide) and lanthanum boride, but these are expensive and hard to cast.

I would like to know some cheap and casteable purple alloy or intermetallic.

9 Comments
2024/05/09
08:10 UTC

1

Why does lead affect the yield strength of commercial bronze?

So, between commercial bronze and leaded commercial bronze, the yield strength rises from 69MPa to 83MPa, why does this happen? The only other property that changes between the two is the hardness (it rises from 53 to 55 HRF), but the elongation % and the tensile strength are the same (45% and 255MPa, respectively)

5 Comments
2024/05/09
02:18 UTC

2

Diamond drill core vs RC Chips for metallurgy testwork

I know diamond drill core is the best sample for metallurgical testwork especially comminution, flotation and leaching. Is it possible to use very old diamomd drill core or is there an industry norm saying older that 5 years or xx years the core is comprimised and should not be used for Metallurgical testwork? How old can the diamond drill core be before we say its no long suitable for merallurgical testwork that will result in either designing a new process plant or used to validate that the ore can be processed through an existing processing plant.

Also rc chips are used quite a bit for leaching testwork. Can you design the leach circuit based off rc chip samples only? I know alot of companies post their quarterly updates showing gold leaching testwork on rc chip samples and say this is the indicative gold recovery.

The questions is can old diamond drill core be used for plant design and up to what extent or would we suggest more recent drilling for oxide ore bodies as an example etc.

Wil apprecaite your thoughts on this?

0 Comments
2024/05/08
02:35 UTC

1

Question regarding OS annealed tempers for copper alloys

So, according to ASTM B601, OS tempers are made to meet specific grain size requirements. My question is, is there any database of how much time and temperature is needed to achieve, for example, an OS-050 temper?

5 Comments
2024/05/07
17:58 UTC

3

Iso: AISI Construction Manual (1930's Ed)

Looking for a copy of the American Institute of Steel Construction Manual 2nd Edition.

Anyone have a physical copy in their archive that they would like to pass on?

0 Comments
2024/05/06
17:52 UTC

1

Phase diagrams

I dont know if it is a good place, but i have a question.
Where i can find phase diagrams for Al2O3-PbO or Al2O3-Na6Al3F6?

2 Comments
2024/05/06
14:20 UTC

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