@@misaelmtz8 Kinda figured that was the deal. Would be silly to ask a question, then answer it. Opens the door for easy cheating and so on. So, yeah... makes sense.
Thanks a lot for the content provided. Does this mean you would have to redo the process over and over again, in order to make the entire piece of steel achieve the same hardability or is this process only done in order to understand the affect of the cooling on the crystal structure of the metal and why you would want to cool down the entire object in steel production for a stronger material?
This process is done to understand the cooling rate effects. For all of it to have the same hardness you would quench it. For some applications you want a harder steel like for certain parts of a machine or construction. Applications vary a lot.
6:22 in the sink with the water fountain and the red hot specimen, we can see how it cools down at different rates, but since there is lots of radiation emanating from the cylinder mantle, the cooling isn't only done by the water, especially in the slower part of cooling . This radiative heat loss may infer with the precision of this Lab test! A mirror like mantle around the test specimen, reflecting the IR-radiation back, would improve, smoothen the radial temperature profile and thus reduce the radial hardness differences, making the followiing hardness tests less dependent on the depth of the ground flat surface!
Thanks, I never knew how the tests were done before seeing this video. It's actually very simple set up for the quench, but I'll bet the other equipment needed is 'quite expensive'? Still very interesting though.
It's likely because a hardened and tempered steel tends to have higher hardness to go along with other material properties, when compared to normalized or annealed metals.
You guys have the list of components of the specific alloy and know its quality and usefullness. But one element is missing: Hydrogen! it is hard for a Lab to get a hold on this "volatile ingredient" and it's presence or non presence makes a difference. At higher temperature H gets more mobile and diffuses to grain boundaries, weakening them! The most reliable way to analyze hydrogen content in alloys is in a Research Reactor by measuring the Neutron scattering (hydrogen atoms and metal atoms have very different scattering properties!). it can be done in Garching/Munich, ORNL Tennessee, and Touluse/France. in Britain, I don't know. in the "Greenish-" future, discussed and hyped so much by those many "climate-change-expert experts", Hydrogen embrittlement will become a real pain ! Worse than sulfur or phosphorus! I suspect that the quality of the final steel even depends on the quality of the coke used in the blast furnace; all the oxygen blowing and even vacuum doesn't get H out, completely, once it is in the melt. Have You heard of the problems of the International Standards of weight, the Gold-Iridium Standard-kg (originally smeltered in GB, and then measured in Paris)? Problem is that the samples are drifting apart in weight over a century's time!! Culprit: there was and is a different amount of H in the "kg-Standards", depending which "Standard-kg" was cast first to Last; in that order/row probably! Historically these 18th century standards hadn't been smeltered in vacuum and they hadn't been smeltered on a electrical oven either!
Very few people understand the meaning of "hardenability". This provides a very good explanation.
Awesome presentation
Good vid, though I would have loved to see you actually complete all the tests and produce an actual curve.
Noted. I usually leave that part for my students in the lab to do.
@@misaelmtz8 Kinda figured that was the deal. Would be silly to ask a question, then answer it. Opens the door for easy cheating and so on. So, yeah... makes sense.
There are charts published by steel manufacturers.
Thanks a lot for the content provided.
Does this mean you would have to redo the process over and over again, in order to make the entire piece of steel achieve the same hardability or is this process only done in order to understand the affect of the cooling on the crystal structure of the metal and why you would want to cool down the entire object in steel production for a stronger material?
This process is done to understand the cooling rate effects. For all of it to have the same hardness you would quench it.
For some applications you want a harder steel like for certain parts of a machine or construction. Applications vary a lot.
6:22 in the sink with the water fountain and the red hot specimen, we can see how it cools down at different rates, but since there is lots of radiation emanating from the cylinder mantle, the cooling isn't only done by the water, especially in the slower part of cooling .
This radiative heat loss may infer with the precision of this Lab test!
A mirror like mantle around the test specimen, reflecting the IR-radiation back, would improve, smoothen the radial temperature profile and thus reduce the radial hardness differences, making the followiing hardness tests less dependent on the depth of the ground flat surface!
Thanks, I never knew how the tests were done before seeing this video.
It's actually very simple set up for the quench, but I'll bet the other equipment needed is 'quite expensive'?
Still very interesting though.
thanks for the explanation, but I would like to ask, how long do you cool the specimen in the reservoir jominy?
About 15 min or till cool enough to touch
wich is the article where I can find the grain size simulation, min 3:10, please?
This image came from this source:
en.m.wikipedia.org/wiki/Grain_growth
Many people mistake hardness for shear stregth or tensil strength or modulus of elasticity.
that is where specs of material before playing with it are useful. The dimensions, kpsi and ingredients.
It's likely because a hardened and tempered steel tends to have higher hardness to go along with other material properties, when compared to normalized or annealed metals.
Excelente explicación
Thanks... Good Share.
good!
You guys have the list of components of the specific alloy and know its quality and usefullness. But one element is missing: Hydrogen! it is hard for a Lab to get a hold on this "volatile ingredient" and it's presence or non presence makes a difference.
At higher temperature H gets more mobile and diffuses to grain boundaries, weakening them!
The most reliable way to analyze hydrogen content in alloys is in a Research Reactor by measuring the Neutron scattering (hydrogen atoms and metal atoms have very different scattering properties!). it can be done in Garching/Munich, ORNL Tennessee, and Touluse/France. in Britain, I don't know.
in the "Greenish-" future, discussed and hyped so much by those many "climate-change-expert experts", Hydrogen embrittlement will become a real pain ! Worse than sulfur or phosphorus! I suspect that the quality of the final steel even depends on the quality of the coke used in the blast furnace; all the oxygen blowing and even vacuum doesn't get H out, completely, once it is in the melt.
Have You heard of the problems of the International Standards of weight, the Gold-Iridium Standard-kg (originally smeltered in GB, and then measured in Paris)? Problem is that the samples are drifting apart in weight over a century's time!!
Culprit: there was and is a different amount of H in the "kg-Standards", depending which "Standard-kg" was cast first to Last; in that order/row probably! Historically these 18th century standards hadn't been smeltered in vacuum and they hadn't been smeltered on a electrical oven either!
Find a different narrator.
That doesn't sound nice, Brother 🙏🏼