Any advice on working metal for my project?

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Fenria

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Feb 7, 2012
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Earlier this year myself and three of my friends started a project for my college (WPI) involving the historical evolution of materials used in arms and armor through the middle ages. We decided to research Japan during this time period, focusing on the Samurai. For this project, we have two deliverables: a rather long paper, and a katana. We found a blacksmith in the area that is helping us make the sword, but we have been running into problems and would like some advice. The idea is to stick as close to traditional methods without going overboard.

The original idea was to use a high carbon steel as a single layer, work it into shape, and use layers of clay on the metal to control the cooling during quench to create the hamon. For this we selected 5160 steel as it seemed to be the one that most accurately mirrored the carbon content of the steel used in Japan during the Samurai. We changed this idea after we got the 5160, and decided that we want to actually make the effort of inserting a rod of low carbon steel inside the 5160...again to keep traditional. This is where we began running into problems. Through experimentation, our blacksmith and I found that we could not get the 5160 to adequately weld to itself. The most we got was 3 small spots of welding...and that was after we heated it to bright yellow and used a vice clamp to squeeze it into a weld. This was after we had met with failure the previous two times we had tried to weld 5160 to 5160 with hammering. We have a rod of low carbon steel that is ready for use, but my question is the following. Is there a way to make the 5160 work in this regard, or would we better served in going with 1075 or higher?

Thanks
 
Yes there is. I belive alot of smiths use power hammers to help aplly enough presssure. Ive heard of peiople doing it with a second person with a sledge hammer and alot use borax and/or kerosene to make sure the wled does just right. I know next to nothing about this since Im a stock removal guy but Im sure some one will chime in soon.
 
This might going overboard? Plenty of modern swords are a single piece of steel, differentially heat treated, clayed, and have a hamon. I am no expert or bladesmith, but for the purposes of your project, why not just focus less on the actual blade process, and more on the final look, shape, etc..
I'm just saying there's lots of other details to figure out, after the blade has been forged. If time was not a concern, it would be a different situation.
 
Might also move this to the shop talk area. You'll find a lot of the makers there who may be more able to help.
 
It has been my (very) limited experience and the observation of the experienced blacksmiths I have been exposed to that borax (or other suitable flux) will help a LOT. . .getting the part hot enough and applying the pressure as quickly as possible will be helpful as well.

I have seen forge welding done with a hand hammer and flux, and I have seen 5160 used on a multi-layered blade as well so it can be done.

Hope that helps some.
 
If I remember right 5160 is a through hardening steel. The Japanese used a shallow hardening carbon steel. This meant they could use the clay to slow down the quench along the spine. The edge was made up of martensite which takes up more space and is harder than the spine - resulting in the upward bend of the sword. The area on the blade where the martensite meets the pearlite is shown by the hamon. I do not know how good of a hamon 5160 will give you. I don't believe traditional Japanese swords have much chromium or manganese in them.
 
I admire your project, however 5160 would not be an ideal choice for a hamon. It is a deep hardening steel and will not show much of a hamon, more of a diffuse transition zone. I would suggest using 1075 or 1060 for your steel. These are simple carbon steels without a lot of alloying elements and respond well to clay coating, provided that you heat treat them correctly. 5160 will make a good sword, just probably not what you are looking for.
 
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