Tabor wrote:Snake oil, however, (the real stuff) might be used as a stinky way to help slow oxidation. Snake oil actually worked so well for inflammation that people could make money selling fake snake oil....[long explanation of snake oil
If we called it bullshit, would you write an article explaining the antioxidation properties of cow manure?
Rick "just wondering" Denney
As for the sonic qualities of the bullshit treatment, I do not know, but this is a good area to be explored. I did, a quick internet search, to find that both manure and heat are used in the forming of cast bells (see reference below) Interestingly enough, horse manure is used in the manufacture of bells, rather than bullshit. Now, steers are more typically finished than bulls (or cows for that matter) with the modern diet of corn. While steer manure and bull manure, however, may differ in composition due to the intended input and output. The increased acidity involved with the corn-fed steer of a large containment finishing facility might make easy work of collecting a sample, however it also presents a difficulty to our sonic testing process, as we wouldn't want to confuse steer vs. bullshit in our comparison with the more traditional horse manure/heat preparation...
As a metallurgist* I am always fairly impressed with the level of understanding and sophistication that is displayed in forums like this when it comes to working with metals. I just thought I would add a few minor details.
Metals are made up of many many little crystals all stuck together. Brass is an copper-zinc alloy where the crystals are cubic either face-centered (alpha brass like aluminum or silver) or body centered (beta brass, vanadium, chromium, sodium). The crystal structure of brass is solely dependent on the alloy chemistry. Alpha brass is less than 35% zinc. Beta brass is between 45 and 50% zinc. If you have between 35% and 45% you get alpha-beta brass which is an alloy with distinct (microscopic) regions of alpha brass and beta brass. Zinc has very significant solubility in copper and mix well.
Steel on the other hand is made by adding carbon to iron at amount varying from 0.02% to 2.1%. At most temperatures the solubility of carbon in iron is virtually zero. At room temperature iron is a body centered cubic metal, alpha-ferrite. If iron is heated up above 1000 degrees or so it can dissolve up to 2% carbon and transforms to gamma-austenite. Now if you slowly cool the austenite the carbon will leave the solution by diffusion and form non-metallic compounds like cementite FeC3 or pearlite. However if you rapidly quench the metal the carbon does not have time to move and is frozen in place. The presence of the carbon does not let the iron go back the the body-centered cubic it forces a new phase martensite to form which is body-centered tetragonal (brick shaped rather than cubic). This change also comes with a volume difference so any ferrite is under internal stresses that can cause cracking and other bad things. Martensite is very hard (I will explain why in a second) but also very brittle. So it is common to temper the steel which is to heat it up a bit and let some of the martenisite return to ferrite and cementite. This process is a real art, and that blacksmiths and craftsmen of all kinds were able to figure it out constantly amazes me. This quench and temper process is called heat-treating. You are strengthening the metal by the heat-treatment process.
When metals deform it occurs (mostly) by a process called slip. Slip occurs when layers of atoms in the crystals slide past each other. Now this is a difficult proposition. Imagine draging a large area rug across another carpet. However the process can be made easy if you put bump in the rug and push it along. You are only moving a small part of the rug at a time. Now in crystals there are defects called dislocations that allow slip to occur. How hard a metal is a function of how easily these dislocations can move. Face centered cubic metals have many different ways these dislocations can move and are relatively soft. Body centered cubic have less then hexagonal metals like titanium followed by the body centered tetragonal magnesium. Martensite will break because the dislocation have very few ways they can move and the metal becomes very brittle. Metals work harded (cold-work) becuase these dislocation multiply and become entangled. The rate of work hardening is (largely) governed by how likely these dislocations are to become immobile and has to do with something called the stacking fault energy.
Brass does not undergo a transformation from one phase to another by heating and cooling like steel does because the zinc is very soluble in the copper. Now beta brass is going to be harder than alpha brass because of the crystal structure. When brass is worked these dislocations will multiply and get tangled together. The brass becomes very hard, looses ductility and becomes stronger. Heating brass will allow those dislocations to move and become untangled- this is called recovery. If you heat brass hot enough something called recrystallization will occur new tiny crystals will nucleate and grow and in the process "eat" the grains or crystals with the tangled dislocation and a very soft virtually dislocation free metal will the result. This is annealing. No matter how you heat brass it will get softer. This is why reloaders can take their spent casings heat them up with a propane torch and drop them in water and they are good as new. Try that with a steel chisel and you are likely to ruin the chisel (if you are likely) or cause all kinds of cracking.
Sorry if this is overly technical, but I just wanted to be as accurate as possible. Nothing that was said in the forum was actually wrong, but it can be very confusing.
TLDR: Annealing makes things soft, heat treatments make them hard.strong. Brass can not heat treated.
* (of sorts I hold a Ph.D. in materials science and my current research is in deformation mechanics of metals with a hexagonal crystal structure like magnesium and titanium, but I have never been a foundry metallurgist. I am also a licensed aircraft mechanic who has quite a bit of welding and brazing experience)
Gocsick, there may be only a couple of us that followed you through to the end, but I for one appreciate the clear explanation and the expertise behind it. As a civil engineer, I'm consumed by application rather than process and tend to draw conclusions from mechanical properties rather than what's happening at the molecular level. I thank you for the primer.
Rick "who mostly repackages the expertise of others" Denney
I think it was in the fall of 1967 I saw that movie shortly after it opened in Copenhagen. I don’t remember the plot in all details, but I think it was the murderer who worked in a café, where Tippet(?)-Poitier wanted some cake. Next time the bad guy sees Poitier coming and places the plate with the cake under the counter and tells it being sold out. Oddly enough I also remember the train sirene and the greenhouse with the orchids.
