I bought some HSS stub drills, and treated half of them with liquid nitrogen, which improved their wear resistance dramatically. I also look at the change in microstructure with an electron microscope.

Performance of cryogenically treated M35 HSS drills - http://sci-hub.ru/10.1007/s00170-011-...
Performance of cryogenically treated HSS tools - http://sci-hub.ru/10.1016/j.wear.2006...
Effects of Cryogenic Treatment on the Strength
Properties - http://sci-hub.ru/10.1088/1757-899X/2...

LN2 generator video:    • Liquid Nitrogen Generator - Overview  
Heat treatment of steel video:    • Intro to heat treatment of steel (har...  

Source of drill bits: https://www.mcmaster.com/catalog/125/...

Temperature logger (discontinued, unfortunately): https://www.adafruit.com/product/3081

3M fine polishing pads: https://www.amazon.com/Tri-M-Ite-Poli...

Delorean patent on cryogenic torsion bar: https://patents.google.com/patent/US4...

Steel grain structure inspection, and overall great channel for material analysis:    • Metallography Part II - Microscopic T...  

Steel grain structure video:    • Grain Structure of Steel  


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