Questions tagged [metallurgy]
Metallurgy is the science of the production and the processing of different metals and other metallurgic usable elements.
174
questions
19
votes
4
answers
33k
views
What material is used to hold molten iron in a furnace?
When iron is melted, I guess it has to be transported and contained. I think the container in which it is has to be able to withstand higher temperatures than what you want to melt.
According to this ...
- 791
19
votes
1
answer
964
views
Can we change steel properties by application of magnetic field while quenching?
Austenite is non magnetic while $\alpha$-ferrite and pearlite are magnetic. (Magnetic properties of pearlite vary as a function of carbon content)
If a strong magnetic field is applied in a ...
- 1,413
13
votes
4
answers
6k
views
How can I tell if I got counterfeit aluminum?
I recently received an order of extruded aluminum strip 3/32" thick that supposed to be 6061 hardened to specification ASTM B221. However, when we tried to bend it, it broke and the interior ...
- 1,625
11
votes
3
answers
2k
views
Could a gold/{second metal} crown be created that would pass the Archimedes test cost effectively?
Many people are familiar with the story of Archimedes submerging a crown in water to identify if the volume of the crown was consistent with the volume of the same amount of gold. The test was to see ...
- 1,062
10
votes
4
answers
3k
views
How can the alloying materials of recycled steels be separated?
As I know, a very considerable part of the currently processed steels (around half of it) is coming from recycling.
But during the steels coming into the recycling process are coming normally from ...
- 2,369
10
votes
2
answers
8k
views
What made bronze the first widely used (non-ornamental) metal in human civilization?
I recall learning about the bronze age in school. Why was bronze so important to the technological development of humans? Why not some other metal?
- 1,062
10
votes
3
answers
9k
views
At what temperature do I risk altering the structure of steel?
If I have structural or tool steel that has been treated to some standard (ASTM, SAE, ISO -- e.g., for hardness) but I don't know the details of the treatment, is there a "safe" temperature below ...
- 1,757
9
votes
4
answers
4k
views
9
votes
1
answer
2k
views
Stainless steel corrosion resistance in seawater
Stainless steel comes in several qualities.
AISI 303 (1.4305) (Stainless Steel A1) approximately 304 but more machinable due to sulfur.
AISI 304 (1.4301) (Stainless Steel A2) comprises of 18% ...
- 427
8
votes
2
answers
2k
views
Unknown metal-piece connected to the case of an iPod Nano 2
I disassembled an iPod Nano 2 yesterday and was surprised to find a round brass-coloured plate glued to the back. I didn't find any mention of it at the teardown over at ifixit.com, as they didn't cut ...
- 83
8
votes
1
answer
2k
views
Why does faster cooling produce smaller grains?
I've learned that in general steel and other metals tend to have smaller grains when cooled quickly and larger grains when cooled slowly and that at higher temperatures, the grain size grows even if ...
- 89
8
votes
4
answers
8k
views
What bolts should I specify with Weathering Steel?
When using weathering steel (COR-TEN) on a project, what sort of bolts should I be using?
I have yet to see fixings made of weather steel; presumably because the way it uses a sacrificial layer to ...
7
votes
5
answers
19k
views
Copper is more conductive, so why use lead battery terminals?
Copper is around 14 times more conductive than lead according to this source. If this is the case why are car battery terminals and connectors built using Lead? I saw both types of replacement ...
- 81
7
votes
5
answers
647
views
How can we prevent/detect hydrogen embrittlement?
There has recently been a series of high profile bolt failures on 'The Cheesegrater' in London, which have been attributed to hydrogen embrittlement.
What can engineers do to ensure that hydrogen ...
7
votes
1
answer
149
views
Special Considerations for Steel Plate Marketed for Laser Cutting
A contractor working for me on a steel construction project is using a steel product they refer to as 'laser plate' which is marketed as specifically as having good performance on laser cutters. This ...
- 4,531
7
votes
2
answers
230
views
Can high alloy tool steels be quenched in brine?
It is will known that most of tool steels are quenched in oil to prevent cracking and distortion which appears when quenching in water due to non-uniform cooling caused by formation of insulating ...
- 81
6
votes
4
answers
674
views
What is the purpose of grid-like details on engine blocks?
It is common to find this kind of detailing and patterning on engine blocks and related parts. Older engine blocks display much more flatter and simple geometry and this kind of mold work must come ...
- 61
6
votes
3
answers
21k
views
Why use a 'dogbone' shape for tensile testing specimens?
Why is that the shape of the tension test specimen a dogbone-like shape?
I know that it is so that the deformation is confined to the narrow center region and to reduce the likelihood of fracture to ...
- 517
6
votes
1
answer
5k
views
Schaeffler, De Long, and WRC welding diagrams - which steels can be used?
I am working on a simple program that would help welder to count how much ferrite, austenite etc. there is in weld. I am focusing on stainless steel.
I have decided to use 3 graphs: Schaeffler, De ...
- 205
6
votes
1
answer
8k
views
Densities of different phases of steel (austenite, bainite)
Steel seems to be a very complex material, not least because of the different phases and microstructures. At the moment, I'm especially interested in the bainite formation that happens when austenitic ...
- 163
5
votes
4
answers
775
views
Can you get quality welds from a multiple metal wire feed welder, or do you need separate units for steel and aluminum?
The job site requires welding both aluminum and steel (each to themselves only) for different areas of the project. The contractor has a dual purpose wire feed welder (aluminum and steel) but I am ...
- 1,062
5
votes
2
answers
8k
views
What's the difference between annealing, curing and sintering?
All these processes sound like structural change caused by heating.
- 223
5
votes
2
answers
3k
views
How does the S-N curve (or Wöhler curve) of a material change with frequency?
How a Material fatigues can be characterized by a Wöhler curve where each datapoint corresponds to a failure with the stress on the y-Axis and the number of cycles on the x-axis. An example is the ...
- 1,618
5
votes
2
answers
92
views
Non-toxic material for deformable wire/rod without work hardening
I am looking for a non-toxic material for a wire/rod that allows room temperature deformations without work hardening.
Example uses are semi-rigid cables that one can bend and that hold their shape ...
4
votes
2
answers
567
views
Why does corrosion take place at certain stressed regions?
Why does certain parts of metal show more corrosion at the place where there is high dislocation density in comparison to the place where the dislocation density is less? I do sincerely feel that this ...
- 281
4
votes
3
answers
982
views
Is there a maximum life for things made out of stainless steel or cast iron?
Do steel objects have a maximum lifespan? I read that "316 stainless steel is estimated to last for 1200 years in a “rule“ environment before heavy pitting. In the marine environment this is ...
- 41
4
votes
2
answers
2k
views
Why is strain also normalized to the parameters of engineering strain?
I get that you normalize stress to engineering stress, so that it is independent of the cross sectional area. This means you can calculate (roughly) the stress needed to elongate the specimen to the ...
- 517
4
votes
1
answer
206
views
Determining the microstructure of steel after welding in modern computer software
How can the microstructure of steel after welding be determined in modern computer software?
I am aware that there are 'classic' methods of predicting microstructures like Schaeffler, DeLong or WRC ...
- 205
4
votes
1
answer
7k
views
Does unloading beyond yield point also affect tensile strength?
I know that with strain-hardening you increase the yield and tensile strength. So if you unload at point D, then you also have cold worked it a bit right?
So the stress-strain curve will look ...
- 517
4
votes
2
answers
9k
views
How does a graph with tensile stress-strain curve and compressive stress-strain curve superimposed look like involving true stress and true strain?
If you have a graph with a tensile stress-strain curve of a typical metal or alloy and you superimpose a compressive stress-strain curve on it (from same metal or alloy), how would this look like if ...
- 517
4
votes
1
answer
197
views
How small can you get a stream of molten steel to be at low pressure?
I'm designing a crucible / extruder, and right now it has a .6mm hole to extrude from. Will this work? A chart with various metals listed would be nice.
Pictures:
Click to expand
- 423
4
votes
2
answers
666
views
Estimate the grain size after grain growth
An uncold-worked brass specimen of average grain size 0.009 mm is heated to 600 degrees Celsius for 1000s, what is the average grain size based on this graph?
How to tackle this problem? I don't know ...
- 517
4
votes
1
answer
11k
views
How to bend copper heat pipes?
I have purchased these copper heat-pipes; however, I am wondering how to bend them without kinking them or cutting them open due to pressure on weak points/bends.
These are flat copper heat pipes, so ...
user15044
4
votes
1
answer
827
views
What actually cause quench cracking, non-uniform cooling or rapid cooling?
It’s well known that quenching most alloyed steels starting from AISI 4140 to high speed steels in water, brine , or sometimes oil will cause cracking and distortions.
In industry, oil quenching is ...
- 41
4
votes
0
answers
74
views
What is the theoretical grain size in an ideal phase diagram of a metal?
We suppose thermodynamic equilibrium in a phase diagram, where cooling rates are infinitely long and diffusion in both phases can finish completely. So when we cross the solidus line and we are left ...
- 161
3
votes
2
answers
715
views
What is the strongest known *metallic* material which can be used on Earth?
The discovery of nanotubes and graphene has pushed the limit
of material strength high enough that building a space elevator
could be managable. But most of the new materials are created
from carbon ...
- 409
3
votes
1
answer
7k
views
Theoretical strength of pure and perfect crystals are way higher than the strength of crystals with dislocation?
Apperently in the beginning of material science they theoretically calculated the strength of perfect crystals, which was way higher than the experimental strength. The difference was later ascribed ...
- 517
3
votes
1
answer
2k
views
Is it necessary to preheat an investment casting mould when working in a vacuum?
Normally, in investment casting, the mould is preheated before pouring the liquid metal in to reduce thermal shock from rapid cooling.
In a vacuum, the heat transfer due to gas convection is reduced ...
- 193
3
votes
1
answer
205
views
How the choice of etchant can affect the severity of hydrogen embrittlement during pickling and passivation?
Following this question, I am trying to understand how/if the choice of acid we might use during the pickling and passivation of certain metals, can influence the severity of hydrogen embrittlement. ...
- 249
3
votes
1
answer
408
views
Can Rotary Friction Welding be used to join metals and ceramics?
Is Rotary Friction Welding a good method to join cylinders of a metal (such as Ti alloy) and a ceramic (such as SiC).
I know that Diffusion bonding can be used in such cases. However, it has its own ...
- 131
3
votes
1
answer
621
views
Purpose of a GD-Zn alloy
Here are screenshots of the data-sheets of two separate products for a reference. They both are nickel plated, used for coupling nuts. The former is shielded, the latter is not, I wonder if this is ...
- 133
3
votes
3
answers
91
views
How do I calculate the Cr concentration in an Fe-C-Cr alloy?
Say, I have a 0.1 % C and 18 % Cr in a Fe-alloy. At a particular temperature, we have precipitate formation (of Cr23C6), which requires many Cr atoms. At a given temperature , how do I evaluate the ...
- 151
3
votes
1
answer
223
views
Can the US realistically mine and produce all Rare Earth Elements, without relying on China? [closed]
Why exactly isn't the US mining and producing its own rare earth metals (REEs)? I'm baffled by the mixed messages below. Because China uniquely possesses some REEs? US safeguards against pollution ...
user24573
3
votes
1
answer
1k
views
Why is the Poisson's ratio for isotropic 1/4 and the maximum value 1/2 (when there is no net volume change)?
It sounds logical untill I tried some thought experiments. So I must be doing something wrong. Or I am missing a fundamental aspect.
What I thought of was:
-lets say you have an orthogonal ...
- 517
3
votes
2
answers
218
views
Where does one go to produce custom metal objects?
I am wanting to produce custom mass plates for a project, very similar to those found in gyms. Here's a rough idea of what each one should look like:
This is essentially identical to mass plates one ...
3
votes
1
answer
1k
views
Is stress relieving by stretching necessary when performing a T751 heat treatment after a T651?
We have a 7075 Al pump housing that has currently undergone a T651 temper but requires a T751 treatment to alleviate stress corrosion cracking.
Is it necessary to re-stretch a 7075 aluminum part to ...
- 716
3
votes
1
answer
72
views
How do old wind turbine towers pickup magnetism overtime?
I was conducting some robotics tests on a old wind turbine today, and noticed strong magnetic fields around the steel tower. This magnetic field does not exist on other modern wind turbines at the ...
- 31
3
votes
1
answer
379
views
What material should I use to store molten metal?
I'm performing an experiment based on slag corrosion behavior of the refractory material. I need to store molten metal at $\approx$ 1600-1700 K for that.
Specifically, I'm working on slag corrosion ...
3
votes
0
answers
1k
views
How do I EXACTLY calculate the k-factor for metal bending?
Introduction
I've recently started to work with metals and the process of bending them. There is a lot more math involved than I initially thought. All the break press operators just have a ...
- 31
2
votes
2
answers
919
views
Why are vacancies in solids called as equilibrium defects?
My professor, when discussing about Random Walk model during diffusion in metals said that "Vacancies are equilibrium defects but dislocations are not". I could not understand why. Why is it so?
- 23