For someone whose native language is not English, who is studying mechanical engineering and is due to take a materials final, I find these videos incredibly helpful and am grateful I found them. Thank you very much for simplifying the issues in question. Greetings from Argentina!
Sir. indeed an informative video, keep enlighten us. I request you to make some shots of TMT Bars (Primary and Secondary), and causes of failures. Thank you.
Thanks and glad to hear it was useful. Thanks for the suggestion for future videos. I have a list of potential next ones, but just need to find the time to create them
The three videos you have produced about phase diagrams, phases of steel, and this one are extremely well done. They are very easy to understand and I am grateful that you spent the time to put them together. Do you have a video on the bronze (Cu-Sn) phase diagram, or know of one?
Thanks! Appreciate the comment and glad to hear it helped. Unfortunately, I haven't got a video on Cu-Sn phase diagrams. Doing a quick search I can see there's a lot more going on in that specific system. The content out there seems mostly focused on research papers
Usually alloys which have a composition where at room temperature they exist in a 2-phase solid region. Some examples might be aluminium, titanium and nickel alloys but there are many others. The key is that you can create this second phase to hinder atomic movements and strengthen the material
Exquisite delivery! Several centuries' worth of knowledge effectively and clearly disseminated in a few short lectures. I doff my hat for you Dr Wu. Thank you so much.
Thanks a lot Dr. Wu. You have the best explanations on youtube. I don't generally understand this stuff but you made it so clear that even I was able to clearly understand it. You basically summarized my 2 hour lecture in 15 minutes. Would have loved to have you as my teacher. Once again thanks a lot and I wish you did more of these videos on other topics that would really help ......
i have my intro mat sci final tomorrow and you genuinely saved my ass...please continue to drop in those little logical explanations of yours they are very helpful in avoiding simple memorization
Just watched the three videos on material science you have and WOW. You explain just the fundamentals and very well, and everything makes sense. Thank you so much for making these!
Thanks Billy Wu ....Your videos have been so helpful and gives lucid explanation. Thank you so much. I have one request. If you can make a video on Gibbs Free energy, it would be great.
Hello, in the TTT-diagram, shouldn't the cooling lines be straight (temperature held stable) when entering the red pearlite part? Or is that not required? thanks!
Mixing things up. Deformation in high temperatures and grain size evolution vs cold working. The Hall-Petch equation cited is only valid for ambient temperature !
a. It may be seen that the time to peak hardness and the peak hardness itself are a function of the ageing temperature. Why does the curve at 30 °C not obey this general trend ? b. It may be seen that at the temperatures 110 and 130 °C an initial hardness plateau occurs before the peak hardness is reached whereas this is not found at the other temperatures. i. Why is such a plateau found at those two temperatures and not at the higher temperatures? ii. Would you expect such a plateau also at 30 °C, although at longer times? help me with these questions
When cold worked via the milling process, what level of hardness could one expect for the outer shell of 303 stainless steel? Thank you for such an informative video.
Thanks a lot. I genuinely didn't know a thing about metallurgy and metals. But as I work closely with metal manufacturing I forced myself to understand the basic theory of how it is made. This video of yours explains so clearly the factors that affect the hardening of metals. I am so glad that professionals like you would share things that You've spent years to study and make it so easy to understand. really appreciate!
Your way of explanation helps me to recall of what I studied from mechanical engineering.. especially your pronunciation easy to follow first non native English spoken person
This (paired with the first two videos) is an absolutely incredible introduction. I feel like i understand the heat treatment process 10000x better, wow.
Dr. Wu.. Thank you. I'll be watching this video multiple times to better my gas turbine engine reports and the material run time damages they under go through out the engine's service life. I perform inter-stage inspections by video-scope and often wonder why certain materials and rotating parts have accelerated loss of strength and other areas and material types don't. It seems as if the single crystal process is the latest high temp, high tensile strength most tolerant in the engines I represent. Thanks for your time and mostly for simplifying the video.
Thanks. Glad to hear it was useful. Heat is one of the major factors which can influence the strength of a metal; impacting the grain structure and phase composition
Great question. The challenge with precipitation hardened alloys is that they are thermodynamically unstable and eventually will revert back to the thermodynamic composition and lose the strengthening benefits of the heat treatment (though this can be quite slow in some instances). Alternatively, dispersion strengthened alloys can also provide good strength by mixing in small particles of oxide materials into a metal matrix. The advantage here is that since the 2 phases are thermodynamically stable relative to each other you don't lose the strength at higher temperatures as precipitation hardened materials would.
Thank you Doctor Wu for this very easy to understand video. I have one doubt regarding precipitated hardened stainless steel. We regularly use SS17-4 PH. The problem is the physical properties vary a lot after H950 for every part. We currently procure the material in Condition A (Solution annealed from 1042 °C), after doing the major boring/drilling/turning job, and then age harden it to H925 for 1 hour/25 mm cross section thickness (also acting as stress relieving). The problem is that we are getting elongation ranging from 8% to 15% and hardness from 34 to 43 HRC, which is too broad to categorise in any HT condition. Please suggest what should be the ideal way to process the material.
Hello Dr. Wu I have a requesting you to make video on Fe-C Diagram with your lecture where non metrologist can understand easily. Please it is my personal request to you. it helps me and others can get benefits on your lecture as always
Excellent video. I would like to include practical examples of the process for all three hardening techniques with constituents mentioned with weight or percentage to visualise the actual alloying process creating strength, ductility and resistance to corrosion
I adapted it from "Materials science and engineering" by William Callister. Fantastic foundational book for material science. Redrew it so that I can animate it so the exact positions might be slightly out but the core principles are the same
@@BillyWu Found it online, excellent. Thanks. I have an advanced question, maybe you can answer it... if larger grains are usually associated with weaker macro properties, how are single crystal turbine blades stronger than a blade made of many smaller crystals?
@@joshtargo6834 Great. Generally single crystal metals will have a lower yield strength than polycrystalline materials due to the absence of grain boundaries and their interactions with dislocations. However, single crystals have other properties which make them attractive in some applications such as anisotropic properties. One of the common examples of single crystals is in turbine blades, where single crystal metals are ideal since they have lower creep resistance, but they are generally expensive to manufacture. Single crystal silicon is ideal since it helps with the electrical properties.
A lot of people have already said it, but thank you very much again. You managed to fit two months of a semester or even more into 3 videos lasting just an hour in total. God bless teachers like you, who make the education accessible and easily understandable.
Generally cold working/work hardening increases the number of dislocations as the plastic deformation causes the dislocations to interact with each other and multiply. The wiki page has a bit more of a deep dive into this en.wikipedia.org/wiki/Work_hardening
