Metallurgy Details

HWS-1S / HWS-2S Katana

Announcing the all new Lion Dog and Bamboo Mat Katana from CAS Hanwei!

Available now, these two attractive katana join the Silver Anniversary Shinto in an exciting line of swords utilising Hanwei’s own High Alloy Steels (HWS-1S and HWS-2S). Made in Hanwei’s new factory, these two high-tech steels are proving to be not only unrivalled in their performance and resilience but Hanwei is paying special attention during differential hardening to produce some of the most intricate hamon styles and variations we’ve yet seen. This revolutionary blade material along with the traditional sword fitting themes combine to create a high quality package at very attractive prices.

The Lion Dog Katana features an O-Kissaki blade of HWS-1S steel, which combines superior performance with an outstanding O-choji hamon. This steel offers the best edge-holding capability and resilience of any blade ever produced by Hanwei. The outstanding performance characteristics of blades forged from HWS-1S steel derive from a combination of the careful selection of alloying elements and a complex processing procedure, basically involving the manipulation of the steel’s carbon content across the blade section. This results in a very tough and resilient blade with a hard, highly abrasion-resistant edge. The sharply detailed fittings feature a Lion-dog themed black iron tsuba, with matching fuchi/kashira and golden peony menuki. The complex saya features a gloss-lacquered ribbed section at the koiguchi/kurikata with the balance spatter-lacquered for a very attractive appearance. The premium multi-coloured sageo is hand-woven in pure silk.

Our Bamboo Mat Katana features a Chu-Kissaki blade in the Shinogi Zikuri style of HWS-2S steel, which combines impressive performance with a striking O-choji hamon. The fittings feature a bamboo-themed black iron tsuba, textured in a bamboo mat design with a jointed bamboo rim and highlighted with gold-tipped bamboo leaves. The fuchi/kashira follow the same theme and the golden menuki feature a pair of sparrows. The saya is finished in high-gloss lacquer with horn fittings.

James Williams of Bugei testing HWS-1S steel on yellowed bamboo

Tamahagane Steel

Tamahagane steel is made by building and firing a Tatara, the traditional Japanese sword-steel smelter. This charcoal-fired furnace produces a very pure steel from iron sand, and this steel “Kera” or bloom can be broken and separated into high- and low-carbon pieces, which respectively form the “skin” steel and “core” steel of the blade. The skin steel is forged and folded repeatedly, to remove slag inclusions and voids and is then wrapped around the core steel before the resulting billet is forged into a blade. Careful heat treating, shaping and polishing reveals the tight “Hada” or layer pattern of the blade and the white particles of the “Hamon” or temper line. While this process results in the aesthetic qualities much admired by collectors it also produces a very functional blade, as the high carbon content of the skin steel makes a very hard edge possible while the softer core steel gives the blade its resilience and ability to absorb shock.

1) The steel is smelted in the traditional Tatara furnace creating a 'Kera' or bloom of raw steel. This bloom is broken into pieces by hammering and the pieces are separated visually by an accomplished smith, who can determine carbon content of each piece by its appearance.

2) Pieces of high carbon steel are selected for forming a billet of skin (outer layer) steel while pieces of lower carbon steel are selected for forming a core (inner layer) steel billet. The high carbon skin steel, when differentially quenched, will form a very hard edge while the lower carbon core steel will be softer, providing resilience to the blade and supporting the hard edge.

3) The pieces of high- and low-carbon steel are flattened and formed into separate stacks, ready for forming into billets.

4) Each stack is then covered in burnt straw; which aids in the forging process, and then forged into individual high- and lower- carbon billets.

5) The outer skin steel is folded multiple times to remove slag inclusions and voids. The repeated folding produces a fine Hada (grain pattern) when the blade is finally polished.

6) The folded skin steel is then wrapped around the softer core steel billet and forged into a blade. The blade is then ready to be differentially quenched, using the traditional clay method, polished, and mounted.

L6 / Bainite Steel

Bainite is a structure of high-carbon steel that combines great strength with excellent flexibility and shock absorption characteristics. It has been known as an exemplary Katana blade component for a number of years but its use has been restricted to a few top-class master smiths, due to the difficulties involved in performing the exacting heat treatment procedures necessary for the production of a Bainite blade body in combination with the very hard Martensite Yakiba (edge section) required for Katana blades.

Hanwei has now mastered this difficult process, using billets of L-6 tool steel (a very tough high-carbon low-alloy steel) as a starting point. Blades are forged and shaped in the normal way, then carefully heat treated to achieve the required Bainite and Martensite structures before final polishing.