CNN Talks to japanese Swordsmith

[jasper]

http://www.cnn.com/style/article/fusahiro-shimojima-samurai-swordsmith/

quick article. I like how he talks about folding.

 

[LordEntrails]

Not very in-depth.

It was interesting to be reminded that the blades are water quenched. Makes for a harder steel, but requires more experience than oil as it is less forgiving.

 

[Guest 6801328]

It was interesting to be reminded that the blades are water quenched. Makes for a harder steel, but requires more experience than oil as it is less forgiving.

Water vs. oil is a function of which steel (alloy) you use, not how hard you are trying to get it. If you try to quench an oil-quench steel (e.g. 5160) in water you are risking (and will probably get) cracking. If you try to quench a water-quench steel (e.g. 1070) in most oils it won't harden.* In either case, though, in virtually all situations you still must temper the blade, which reduces the hardness. Sure, it's possible...with skill and luck...to control the quench so that you end up with the right hardness and don't need to temper, but in that case you aren't quenching to maximum hardness anyway. The point being that the goal of quenching isn't to maximize hardness, it's to reach sufficient hardness without cracking. It's easy to make a super hard blade. And it will crack the first time you look at it funny.

*There are quench oils engineered for water-quench steels. They quench (almost) as quickly, but reduce the chance of cracking.

EDIT: Ha! I just read the article. Pretty funny that the whole article is about how this guy uses traditional techniques, but the power hammer (looks like an Anyang 88 or 120) figures prominently in the photos. I have no beef at all with power hammers, and you can still use traditional techniques and just save yourself some work. Still...kind of funny.