Category: Austempering
Most Important Property for Knife Steel? Q&A
New Q&A video with questions from Patreon supporters. Go to Patreon.com/KnifeSteelNerds if you want to support knife steel research.
00:00 Ultra high toughness with ferrite/martensite steels?
05:09 Normalize 80CrV2 with stock removal?
Bainite Heat Treatments of 52100, O1, and 1095 – How Much Toughness?
Thanks to Kevin Colwell, Prentice Goodwin, HallMade Knives, and Saint Apocryphal for becoming Knife Steel Nerds Patreon supporters! And Fixall for increasing his contribution amount.
Background of Austempering and Bainite
The Secret Heat Treatment of Frank J. Richtig
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Legendary Heat Treatments
Last week I wrote about What a Good Heat Treatment Can and Cannot Do, and as part of that topic I wrote about how some knifemakers have a legendary or even mythical reputation for their heat treatments. In that article I argued that the big differences are between “bad” and “good” heat treatments, and that the differences between various good heat treatments are much smaller. And that edge geometry and knife design are more important to knife performance than the differences that are possible between different “good” heat treatments. So I think it makes sense to discuss a particular case of a knifemaker known for legendary, unmatched heat treatments, which brings me to…
Bainite vs Martensite – The Secret to Ultimate Toughness?
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Misc. update: I have added a set of supporting micrographs to the introduction to Austenitizing steel.
Tempered Martensite
To begin describing what bainite is it makes sense to start with martensite first. To form martensite we heat up the steel to high temperature to transform to a phase called austenite where we dissolve carbon in between the iron atoms (see Austenitizing Part 1), then quench the steel to lock in the carbon and form a hard phase called martensite (see What Makes Quenched Steel so Hard?). Following that we temper the martensite to allow some of the carbon out and increase the ductility of the martensite; the carbon comes out as very small carbides, a compound of iron and carbon (see What Happens During Tempering?). In the article on martensite formation I shared the following YouTube video to see the formation of the martensite laths: