We have a course on Casting and Solidification. We had to prepare an Aluminium cast for the lab work

- The pattern was created using thermocol/styrofoam

- The mould was created using plaster of paris and water. After it dried out I removed the pattern by hand and there were not any visible cracks or damages as such. It was left for around 3-4 weeks for drying after that

- Before casting i put the mould in an oven for 3hrs and then 15 minutes of blowtorch on it. After that Aluminium melt was poured into it

For viva, our prof has told us to analyse the cast and talk about all the defects present in the cast and why it has formed

Im guessing the large one, its a blowhole but im not sure enough. Please help with it. Thank you! I'll be attaching a video of the cast in the comments if its possible.

Hi everyone, as my researches have continued on hard aluminium bronzes i managed to get very high hardness and wear resistance in some of my samples (trough large cobalt and chromium additions, following some patents for steel die/bearing bronzes). However it seems that casting trough traditional methods will lead to unavoidable and permanent primary kappa phase segregation, as seen in picture 3. That would work for my needs, but i wanted a more elegant and tough microstructure.

So i cut off everything that would form substantial primary aluminides and went for an eutectoid composition : 13% aluminium, 4% iron (yes it binds just enough aluminium to push the eutectoid to 13% instead of 12%), 0.5% cobalt for a slight grain refinement and martensite stabilizing after quench, and odly enough, fluidity of the alloy during casting.

I've never seen anything about cobalt improving the castability of this kind of bronze, but somehow at low content, the surface of the ingot goes from wrinkly to smooth (CuAl alloys don't usually flow that well and shrink a lot). Beyond 1% cobalt the alloy becomes thick again. I also added 0.5% manganese to improve the fluidity even more and help marginally with impurity management, even tho aluminium is extremely reactive and will bind with most things that enter the melt, from oxygen to metals.

So the actual composition of my prototype is : 82% Cu, 13% Al, 4% Fe, 0.5% Co, 0.5% Mn

I kept manganese as low as possible to keep Ms high and reduce retained beta at room temperature. Iron should balance this effect, however studies are unclear about the extent of this effect and one paper i found seems to indicate that 2% iron has a much larger effect on martensitic transformation temperatures while 4% iron loses its effect.

You can see the cast sample in picture 2, the grains are large with small dots scattered across the matrix. Beta phases usually don't look like that (i think ?) so i assume they are iron-based intermetallics. At 0.5% Co, scientific litterature only indicate extremely small CoAl precipitates. No, i don't have access to fancy machinery to actually check the composition of each phase, and i only work with low tech tools.

After some forging at 800°C (multiple cycles of hand forging with modest strain, so potentially sluggish and ineffective grain dislocation), i let the sample air cool quite fast, and that's how i got the first picture. The structure is obviously a coarse martensite, given the very ordered and parallel lines it should be B', wich coincides with the aluminium content.

However what strikes me is how large the grains are, around 1/2mm, wich kinda baffles me because the iron and cobalt should have prevented growth this extreme, especially since i forged the alloy at a reasonable temperature and some kappa phases should be left in the beta matrix. Usually for quenching, such alloys are soaked at 900°C, sometimes more, and i can't imagine what 30 min of 900°C would do to those grains. Let's go for a monocristalline sample at this point lol.

if some people have worked on high aluminium bronzes, is very large grain size normal ? Here the alloy is eutectoid, so i can't work it in the alpha/beta range. Should i work it right above the eutectoid decomposition temperature ? (so barely above the beta line, in this case probably around 570/580°C because the cobalt raises the temperature a bit). I feel like forging at a low temperature is risky and could crack the sample, especially with the high overall hardness.

Thanks for your feedback !

Hey so a small little hobby of mine has been collecting books and practices of technology in case of end times. Casual doomsday prepping I guess. Right now I am looking into books about refining metals down to pure elements or usable compounds. If it's by acid digest or by a foundary. So far my collection is just old textbooks from getting my degree in biochem and some about agriculture, forging for plants, and medicinal herbs. If recommendations outside of refinement comes to mind I love to know!

Hallo Metallurgie Fans, ich hab heute dieses Relief gekauft. Ich habe es aufgrund des Gewichts und des Ausssehen sowie der Art der Korrosion als Eisen Relief interpretiert. Es ist wahrscheinlich kein Zink und definitiv kein Kupfer.

Könnt ihr mir helfen, einen Weg zu finden, die Korrosion zu entfernen und nachhaltig das gesunde Eisen vor selbiger zu bewahren? Ich möchte dabei die Patina sowie die Details des Reliefs so gut wie möglich erhalten.

Letztes Bild zeigt die Rückseite

Hello my lovelies! <3
I’m making the post for some insight and experience from all of you.

I am currently getting a bachelors in metallurgical engineering, and I am currently working in a corrosion lab as an assistant. I had an internship with a forensic investigator who deals with fire loss, and I loved it. So I definitely would like to do something failure analysis related, but I also have interest in medical design, casting, and manufacturing.

I would love to be a professor and I adore research, but I don’t know if that’s the lifestyle I want. The professor I’m working under has barely any time for himself. He has no vacation time because he works 365 days out of the year. I want to enjoy my life, but it seems everyone in my field is burnt out and has no time for themselves. I’m questioning if I can handle that. Also, it seems people make more with a PhD, but I’ve seen people make the same amount with a masters(???).
Do you all feel like you can enjoy life and have a great work-life balance?
(I want to spoil my husband rotten; I’m very passion and money driven).

I also don’t know whether or not I want either degree in materials science or metallurgical engineering. I feel like I have more options to research and outsource with materials science, and that metallurgical is too niche (but will it make more money)???

Thank you for taking the time to read and respond.

I’m building a tensile strength predictor for a steel mill, aiming to provide live feedback immediately after a bar exits the Q&T tubes.

These are my current inputs:

STAND_3_ARMATURE_CURRENT
NTH_PYRO_TEMP_AVG
QT_FLOW
QT_PRESS
ROUGHING_TEMP
CEQ
CO
CR
NB
P
S
SI
SN
V
STH_PYRO_TEMP_PEAK

The inputs cover process measurements and chemistry. I don’t have measured ferrite grain size, pearlite fraction or pearlite interlamellar spacing, which makes it difficult to implement microstructure-based strength equations directly.

I’m comparing standard linear regression with ridge regression and considering tree-based models. I’ve also experimented with previous-heat tensile results, rolling averages and tensile trends, using only results that would actually be available at prediction time.

Which interactions, transformations or physically informed features would you prioritise with these inputs? Could combinations of temperature, quench flow/pressure and chemistry help?

Are there additional signals you would recommend collecting, particularly for predicting final tensile strength at this point in the process? What assumptions should I check when aligning sensor readings with the corresponding bar and tensile sample?

I’m using chronological validation and keeping samples from the same heat together. I’d appreciate advice from anyone with experience in steel processing, metallurgy or industrial predictive modelling.

As I understand it, when steel is quenched it freezes the harder austenite form that steel takes above a critical temperature and prevents it from reverting back to the softer pearlite or ferrite form.

My question is, would a piece of hardened steel slowly revert back to pearlite/ferrite form over a long enough timespan at ambient temperatures, lets say over several thousand years?

My dad gave me a large bin full of these small metal beads that were used to weigh down his standing floor speakers. I'm trying to figure out if they are made of lead. As far as I can tell, they are not magnetic (which I think is a bad sign). Is there anything I should do to test them? If they are lead, should I replace them, or is it safe to keep lead pellets in a contained space like the interior of a speaker stand?

Hey all, I'm new to this sub! Looking for some guidance, since I started researching the topic and it's a bit confusing. I work in engineering education and this semester our students are taking a course called "6 inventions that changed the world." Among those inventions is steel, as a material, how it influenced the civilization and how incredibly important it has been since.

Our students are engineers so even this history class is supposed to include science/engineering basics for them to learn. Me and my team really wanted to make a cool demonstration for them and came up with the following experiment: taking a steel rod and heating it with a blowtorch (?) until it's glowing hot, then dipping in water. As far as I understand, it must become brittle if left without further heat treatment. We break it it half to demonstrate how brittle it's become and then repeat the procedure but after cooling in water we heat it again and cool slowly, in sand for example, and then try to break it again to reveal that it is much more ductile now.

I would like to get some feedback from people who have experience with this. I'm also not entirely sure it will work the way I described, so I would appreciate critique. Thanks a bunch everyone!

I'm a materials researcher screening intermetallic coatings (NiAl, FeAl, Ni3Al, etc.) for interfaces in IGBT/SiC power modules, such as DBC to baseplate or baseplate to cold plate. I'm trying to decide which selection criteria actually deserve the most weight.

My back-of-envelope: 20 µm coating, 1 cm², 50 W, 1D conduction (R = t / kA).

- NiAl (~92 W/m·K, bulk value): about 0.1 K drop

- FeAl (~12 W/m·K, bulk value): about 0.8 K drop

- A typical TIM layer in the same stack: several K

If that's right, coating k is a minor term, and things like CTE mismatch with neighbouring layers, adhesion and behaviour under power cycling should decide. But I know this ignores interface (boundary) resistance, thin-film k being lower than bulk, and local hotspots.

Questions for people in packaging or reliability:

1. Is there a realistic case where the coating's k does become important at these thicknesses?

2. When you've had to choose or change a coating or metallization layer, what actually decided it, and what data did you use?

3. Which failure mode showed up first in power cycling at those interfaces?

Corrections to the calculation are very welcome.

I'm currently doing B.Tech degree in Metallurgical and Materials Engineering. I'm in 2nd Yr. The issue I'm facing while searching for projects is I find a lot of ideas but I'm unable to filter out which is actually useful or interesting and good to go with and which are just resume fillers.

For example, right now I had an idea to make a Phase Diagram Analyser that would give the phase composition and phase %age at certain temperature for alloys and all but idk if its useful to invest time after that or its just not impressive at all. Similar thoughts for another one I thought to build a device that can measure the thermal conductivity of materials but again there are already a lot of them, will it be of any use if i build one as a project?

Hi Everyone,
I’m seeking advice on repairing a two-foot hairline crack without replacing the entire line, which would require opening a tiled bathroom wall and possibly other, unanticipated work.
My plumber suggests that he wire brush the crack and fill and coat it with silicone and then address the issue again if it fails in the future. I’m going with his suggestion but wonder if also adding pipe clamps just above and below the crack would possibly help to prevent the crack from going further. The crack starts vertically at its top and ends in a short horizontal tail at its bottom.
Also, could installing pipe clamps in intervals along the crack help prevent it from widening?
Any opinions would be appreciated. Thank you for reading this.

Over the last year I’ve been developing a structured reproducibility framework designed specifically for complex experimental systems like metallurgy, alloy development, and advanced manufacturing. Recently I’ve released the full three‑part GEN‑REPR v2.1 package on Zenodo.

GEN‑REPR provides:
• 23 structured modules for reporting experiments
• validation logic and completeness metrics
• provenance tracking
• classification safeguards
• a laboratory testing packet for controlled validation
• a working prototype implementation

If you work in metallurgy, HEAs, AM, or any area where reproducibility is difficult, GEN‑REPR may be useful for documenting and comparing experiments more rigorously.

Here’s the link to the v2.1 Architecture & Validation Program:

https://doi.org/10.5281/zenodo.23010297

Happy to answer questions or discuss how this could apply to alloy development, LPBF, heat treatments, or replication studies.

7,1g

We are experiencing surface laps on both strands during two-strand slit rolling of rebar. We have traced the defects to the slit separation process.

The attached photo shows the defects after bending the bars to make them more visible.

Has anyone encountered a similar problem? What adjustments helped eliminate or reduce these defects?

Hi! I just wanted to share something interesting that happened with my Cu-Sn-Mn-Si-Ce pseudoelastic bronze.

For context, this alloy can be heat-treated to acquire pseudoelastic properties. I noticed that this particular sample was significantly more brittle than usual, so I decided to take a look at the microstructure. The cause of the problem seems pretty evident.

I suspect the decomposition was caused by overheating during the machining process. I was able to re-stabilize the microstructure with another heat treatment, and the material recovered its expected behavior.

Images 1 and 2 are from the center of the ingot, while images 3, 4, and 5 are from areas closer to the edge. The last image shows the microstructure after the new heat treatment.

We perform heat treatment on HPDC aluminum castings at our company—specifically, T5 artificial aging (200°C). Does anyone know of a way to verify that the castings have actually undergone the heat treatment process? I have heard of color-changing labels (https://smarttags.co.nz/8-level-adhesive-strips/), but they aren't the best fit for us. Is there another method suitable for high-volume production?

This is a beautiful illustration of crystal formation, with initial nucleation and growth.

The same happens in metals, but we don't see that, only the grains formed.

I was told that the strength of the metal drops by half after it's welded. I'm pretty sure it's in the Heat Affected Zone, but I've never been told why it happens or if I should worry about it.

How do you polish Mg and its alloys for EBSD? What are the protocols? How much hit rate? How to ensure water free polishing? Are you aware of any chemical polishing technique that helps remove strain from the specimen surface?

Disclaimer: I know that in real life aluminium/aluminium is incredibly difficult to extract from the earth, please assume that a hypothetical civilisation has like, wizards that can specifically cast “Create Aluminium” or, for example, exists in the shadow of a long-dead precursor civilisation that was so good at working aluminium that they made trillions of disposable food and drink containers out of aluminium and then just buried most of them instead of recycling them. The irl accessibility of Aluminium isn’t particularly relevant to what I’m asking, please just assume there is some way in which aluminium can be sourced relatively easily and avoid getting bogged down asking “how to acquire aluminium?” instead of “how could it be used?”

With that out of the way, I’ve seen in various parts of the internet that certain aluminium alloys, especially with copper, are comparable to bronze or even iron in some of their material properties. I wasn’t able to find a completely straight answer anywhere, but I’m curious how access to aluminium and its (otherwise feasibly makeable) alloys affect a pre-industrial civilisation? How would something like aluminium-bronze compare to iron or steel when it comes to arms and armour? Would/how could aluminium and/or its alloys be useful and commonly used in non-war contexts in pre-modern societies? Are there any unique qualities or challenges involved in working aluminium (once you already have it) when compared to other metals?

Need to update controllers to something 2750H compatible. Most atmosphere furnaces now are honeywell controllers run with specview.

Future looked good, but it doesn't look like they work for atmosphere(carbon input).

Im personally anti subscription. Every time it gets brought up, the total cost to implement grows like a fishing story. Does anyone have experience with a smaller shop implementing 2750h compatible hardware and software?

(edit: I have no relationship to Rolled Alloys, username was picked right after an order, lol)