what makes japanese chisel steel so much harder?

Originally Posted by jamie shard

My question is what makes the steel in Japanese chisels have such a significantly higher rockwell hardness? Is it the elemental blend (more chrome, vandium, etc.) or is it the forging process which compacts the carbides or is it tempered less or is it something else entirely?

Japanese chisels tend to be, but are not always, harder than Western style chisels because they are intentionally heat treated to be harder. This is easy to do, but hard to make practical.

They can tolerate the extra hardness partially because of the laminated structure of high-carbon steel and low carbon, relatively softer and therefore tougher, steel used to make chisel blades. A western style chisel blade made of uniform high-carbon steel structure would simply break if heat treated to the same hardness.

Another reason is that the steel is typically (but not always) of better quality, and if forged, will have a relatively more uniform crystalline structure less inclined to chip at higher levels of hardness.

None of this is rocket science or unique to Japan. Laminated chisels and even plane blades have a long history in the West, as does hand forged, high quality steel. The West just abandoned top-quality blade smithing with the industrial revolution. Some of the best-cutting and most durable laminated plane blades I have ever seen were made in Sheffield England in the 1800's, and branded "Cast Steel." The West simply abandoned the techniques still used in Japan.

After cutlery became commonly mass-produced in sweat shops, the really good blacksmiths could not compete anymore with factory products.

The mass industrialization of toolmaking in Western Europe, Northern Europe, and America lead inexorably forward to mediocrity. But in Japan, during this same period, a change in laws forbade the wearing of swords in public (the 'haitorei" 廃刀令 of 1876), thereby ruining the livelihood of tens of thousands of the arguably best blacksmiths in the world. Many of these artisans switched to tool making, and applied their excellent forging, heat treating, and shaping skills to woodworking tools.

In Japan, prior to this change in laws, the more mechanical gun never really replaced the elegant sword. In fact, the government bureacracy and aristocracy of Japan, unlike America and England, have always feared the common man (who until the 1800's were slaves in all but name) owning weapons, and fiercely opposed private ownership of firearms. Therefore, the sword has always been seen as the ultimate weapon. These extremely sharp, tough, and elegant blades have for many hundreds of years been iconic subjects of reverence and lust. This fanatic desire for sharp, tough cutting tools extended to woodworker's as well.

Consequently, while the average skill levels of tool blacksmiths dropped in the West, they dramatically improved on the average in Japan. It is no wonder Japan developed not only unique tool designs, but improved the quality and effectiveness of its woodworking tools. The West has never been as fanatic about sharpness and excellent steel as the Japanese.

I hope this helps.

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what makes japanese chisel steel so much harder?