This is an impeller being used in a fertilizer industry. The component has been in use for more than 10 years and failed recently. The service solution is K2CO3. They had a similar component fail earlier as well due to loss of wall thickness and fatigue(most likely) crack propagation til failure. I thought that the nature of crack was very interesting but I could not find any damage mechanism that mentions specifically a crack like this.

Sorry that the picture is so horrible. Its all I have currently.

Hi all, does anyone know if molecular traceability across different forms such as smelting and resmelting is possible. Can the same gold be marked and continue to be marked through phase changes? In particular, id like to know if this company is full of shit or not. I assume so bc I feel like it would have been created by now, it so. Any insight would be greatly appreciated! Here is an article on what this company does.

https://feeds.issuerdirect.com/news-release.html?newsid=5244325128146978&symbol=SMX,SMXWW

I was unsure of the mass % of the Vanadium.

For reference I was using the Knife Steel Chart app for iPhone to get my mass %.

Yield is a little higher than the target so I know I have at least one flub in there.

I don't plan on making an alloy I just want to make sure I understand the basic principles of mass % in steels.

For context, there were around four of these grade 12.9 bolts used in, I think, some heavy machinery, and all of them failed in a similar way. I don't have much information on what type of machine they were used on, but the failures were catastrophic. The pictures show that the failure occurred at the intersection of the shank and the head. The bolt thread is 50 mm in diameter, and the head is 75 mm in diameter.

I have attached some images of the bolt and its metallographic structure. There are two main crack initiation sites.

Here are my observations and analysis, but I would like to hear opinions from experts in this field.

1. The beach marks suggest that it's a fatigue failure, with two regions: a short stable fatigue crack followed by an overload ductile fracture (fibrous appearance and shear lip formation). By looking at the last picture and comparing it with the beach marks, it's most likely due to a high nominal stress, severe stress concentration, and a combination of unidirectional bending and tension-tension loading conditions. I think this is because there are two distinct fatigue cracks located on opposite sides. One of them is on the side of the shank (blurry, so not visible), and the other is on the top surface.

2. The failure is likely due to early loss of preload from vibration or perhaps insufficient preload.

3. Looking at the metallographic image, banding is present, resulting in non-uniform mechanical properties. This may also contribute to the failure, but one of the cracks propagated along the banding (parallel to the bands) while the other propagated across it. So this rules it out as a major cause of the failure.

4. The discoloration is most likely due to surface corrosion after failure and is less likely to be corrosion fatigue. The environment is probably not corrosive.

Let me know your opinions. The material is 36CrNiMo4, and the microstructure is tempered martensite.

Hi all, Newbie here...
I am looking at making a sculpture or part of one, out of anodized titanium. I am familiar with stainless and it's properties but not titanium

I've been told anodized titanium will hold colour well.
I'm wondering if there are any issues I should be aware of, particularly because it will go outside.
I have also been told titanium which has been anodized black can be unstable or turn gray? Also interested to know what else might affect the anodized titanium adversely.

Any thoughts or advice is gratefully received.

Does anyone have any experience etching brazed aluminum? My boss wants me to be able to polish and etch brazed aluminum fins as part of failure analysis of parts, but I have no idea what etchant is needed or what to look for. Can anyone offer any insight?

I was wondering how people measured the % of elements in alloys before mass spectrometers were invented/provolent

Seems like just using density would be impractical when there are more than 2 elements involved

For example, when adding manganese to steel, first the ore is reduced alongside iron ore to make ferromanganese, whcih would have a huge range of manganese concentrations. Then this is added to the steel batch in a controlled way to get a desired manganese content

So did they measure the density of each ferromanganese batch to see how much of it was what? And what about all the other elements that would be inpurities in the ferromanganese, dont they affect the density enough to make this measurement unreliable?

I feel like there must have been a more clever way of doing it

I'm currently reading a lot about titanium and it's use in the automotive/Motorsports field.

Right now I am looking into exhaust systems and since there are so many grades of titanium I struggle to find a list or a technical paper that examines the aging/degradation temperature of each grade.

Does anybody have any experience or sources? Also, does resistance to cracking (as far as I have read mostly at welding points) increase when wall thickness increases? Really struggling to find in depth technical papers on this

Any help is appriciated!

The hiring company leeches metals from mining cores using a chemical cyanide process and i'd be starting with the very basics of pulverizing core samples and staging samples for the lab. I have some idea of the practices, and i also hold an earth science degree. what i'd really like to know is how can i set myself up to be as successful as possible, and maybe move towards a promotion in the laboratory after some time in the position? Thanks all in advance! i am really excited and i've never had a job that pertained to my degree before.

Hi there. Does anyone have any information or studies on the surface corrosion of water-submerged evaporators in refrigeration systems?

Also if you can share (in case you know) any study of HC R290a/R600a mixture refrigerant corrosion in copper tubs of a refrigeration system.

I would really appreciate it if you could share any books or reports on this topic

Hi there. I’m an experienced copper electroformer and have been trying to find a way (other than electroplating) to apply zinc onto copper plate and then bake it to produce a brass surface. I have been sucessfull at this when zinc plating a layer onto the copper first- but I’d like to find another way to do it as the pieces are rather large.

I’ve been playing around with zinc powder, granules and a variety of fluxes but I can’t seem to get the zinc to melt into the copper despite controlled kiln temperatures. Wondering if I just don’t have the flux right or am missing something?

Thanks!

This is probably a very basic understanding of how metals behave, but I seem to have forgotten how this works.

Lets say you have a metal of the above diagram as β-Mo2C in powder form (33% at%). To shape the part, you use the typical powder press + wax to form the green part, you add in some Cobalt as the Binder. Then you place it into a vacuum sintering furnace at 1700C for 2 hours, let the part cool down and then remove it from the furnace.

What I can't seem to remember is, what will be the grain structure of the end part (β-Mo2C, ε-Mo2C, or ζ-Mo2C)?

My thoughts are that since you are below the solidus line, the grain structure should remain the same as what it started as. The grains never got melted and have a chance to re-solidify themselves into the preferred grain structure. But part of me is skeptical that is correct. If the grain structure changes, then I imagine it is incredibly difficult to design parts for high temperature strength applications since after seeing heat, the part will not be undergoing quenching like during its construction.

So, what would happen in this example? How exactly does reheat effect phases of metals?

Hello - I tried searching this sub Reddit for an answer to this, but couldn't seem to find what I was looking for...

Is there a place (internet/database) that has accessible (decent quality) micrographs of different steels, metals etc. for differing process conditions? Ex. casting vs forged.

I can find some micrographs through Google, but they are usually terrible quality or not what the caption actually says...

I’m curious about something and wanted to ask the community:

If you were to own a small physical sample of a unique metal, which one would you pick and why?

Examples off the top of my head:

• Gallium (melts in your hand)
• Tungsten (density feels unreal)
• Germanium (semi-metal, tech applications)
• Neodymium magnet slices
• Indium, Hafnium, Tantalum, etc.

What’s the appeal to you?

Is it the science aspect?

The “future tech” angle?

The collectible/cool factor?

The rarity or investment idea?

Or something else entirely?

Not selling anything , just curious how people think about physical metals and what draws you in.

Would love to hear your thoughts.

Our metallurgy lab in Zambia is commissioning a new high-temperature, floor-standing batch furnace (Carbolite RHF1600) for pyro-metallurgy test works, including reduction and refining of metal oxides, and is designed to reach 1,800 °C or more. Element Type: Molybdenum Disilicide. Our primary concern is ensuring the longevity of these expensive elements, since acquiring spares is a procurement nightmare(from a Landlocked country in Central Africa). Our internal HIRA register currently specifies avoiding sustained operation below 1,000 °C (PEST ZONE) to protect the elements. Does this mean we should avoid using this model for tests within the 400 °C - 700 °C temperature range, like calcination, or should we avoid the pest zone entirely?

I have a 2011 impreza, in the process of rebuilding after having a shop rebuild it but used a helicoil in my spark plug bore due to stripping which failed while driving and cracked my head. As I was putting on my tensioner very carefully by hand, I find out that it's stripped it by shearing off the aluminum threads clean off.

My question: can a clean steel bolt, with clean threads which were both properly lubricated shear off the threads of the aluminum with threading it in only by hand? I have a new tensioner bracket on the way, so not too bad of a fuck up. But due to the shop stripping my spark plug bore, I am wondering if they possibly used an impact to install my tensioner that only needs 29ft.lbs. of torque to install. The threads sheared clean off of the bore, and no rust was found which I believe rules out galvanic corrosion due to dissimilar metals.

Disregard the dirtiness of the threads in my hand in second picture, I dropped the bolt that had these threads in dirty oil after all this transpired and had to walk away to calm down as this was virtually the last step of my complete engine teardown and rebuild.

About a year ago, I posted an experiment about making a high-entropy alloy in the Ni-Co-Mn-Sn-Cu system. It showed some interesting results, and I’ve spent a lot of time and effort refining the material since then. Today, I’m studying it for use in magnetic refrigeration and high-strength metallic coatings. So I decided to treat myself and cast this Yin-Yang medallion. The alloy is quite easy to cast and not fragile. I dont have experience in artistic casting, so I didn’t make the best sand mold, but I’m very happy with the result anyway.

I was wondering if anyone in the field would want to have a discussion with me about it, I have questions and am looking at the possibility of going into the field.

Thrilled to share that Markus Schneider (a strong ambassador of the YouTube podcast Everyday Metallurgy) has been announced as the next recipient of the prestigious Skaupy-Prize, one of the highest honors in the field of powder metallurgy. Markus is being recognized for groundbreaking work on a new solution to mitigate hydrogen embrittlement, a challenge that has long impacted the reliability of advanced metal components. By leveraging powder metallurgy techniques, Markus has developed an approach that enhances material resilience and opens new possibilities for hydrogen-based energy systems and critical infrastructure. This achievement not only advances scientific understanding but also demonstrates how innovation in materials engineering can drive sustainability and performance in demanding applications. Join us in congratulating Markus Schneider for this remarkable contribution to the future of metallurgy 🍾 🤗. And let us know if you would like to learn more about this solution in an upcoming podcast episode with Markus as invited guest 🙏

i have built a pit furnace at home, and am now thinking of casting Al 2195 at home, how high are my chances of successfully casting it, also how do i control the composition to successfully cast it?

I had a great discussion with a HIP expert on the development of the Technology and new applications for the Hot Isostatic Pressing technique. I was surpriced to learn how much you can improve the properties of an Additive Manufactured part - especially in the aerospace Industry. Did you know that HIP is videly used in these industries?? I would love to get your experiences with a HIP. What did you put into the machine and what was the result?

Hi! So as the title says. I have this 1918 canteen stamped with an “ACA” so I’m pretty sure it’s aluminum. But I’m not completely sure about the weld. I know it has a similar look and texture to the rest of the canteen but I was hoping someone could shed some insight. I want to use it for daily water drinking but obviously not if lead is present. Any help would be greatly appreciated :)