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Spike knife fetish - 440 for the edge


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My first attempt at a blade was a railroad spike knife (of course). My second attempt at a blade was a forge welded san mai from a railroad spike and some questionable coil spring. Having used up both of the spikes I had, a guy at work just gave me a bucket load more. I have a feeling that my next knife may involve a railroad spike. I really like the rustic feel of the spike as a handle contrasting a highly polished blade. A set of steak knives is on the cards.

So far, everything has been an experiment and that's not likely to change. However, it's probably wise to start getting input from those more skilled in the art so that I may produce something that is fit for purpose.

I recently acquired a random bunch of stock... mostly mild steel and 3xx stainless. Luckily, I did find a square bar of 440, although I don't know if it's A, B or C, so I guess I have to assume A? I'm thinking of repeating the san mai, only this time slotting in some 440 instead of the useless coil spring. With that in mind, I have a few questions...

  1. Are there any special considerations when forge welding mild steel to stainless?
  2. Assuming the 440 is A, is it even worth using or should I look for something else?
  3. Given that I don't know whether it's A, B or C, how should I handle the heat treat?

Also, is there anything else I shoud be thinking about for this project?

 

Edited by Mick Morley
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Usually, what you want is a premium edge with stainless sides and not inversely. So get some new known high carbon steel like 1084 for the core and use your 3xx series stainless for the sides. The stock must be cleared of mill scale and ground very clean, especially the stainless. Then, you weld the three bars together completely air tight to prevent the stainless from creating chromium oxydes which will prevent the weld to take place.

Usually, with that sort of stuff, it pays to use known material. You will save money on the long run.

Some more experienced smiths will tune in I hope to add more or correct me. 

Edited by Joël Mercier
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That pretty much covers it.  It is not an easy task in any way, to the extent that a few years ago people would tell you it was impossible.  We know better now, but it's still not easy.

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get some new known high carbon steel like 1084 for the core and use your 3xx series stainless for the sides.

Sorry for the confusion but the outside is going to be railroad spike. The question is really whether I can use that 440 for the center? And if so, how might the process differ from my previous san mai of spike and coilspring? If not then I'll use something else as you suggest.

Quote

It is not an easy task in any way, to the extent that a few years ago people would tell you it was impossible.

My research is pointing that way and it may be a few steps too far for my current skill level and knowledge. Maybe I should go with something non-stainless for the core.

 

 

Edited by MickM
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Also, some spikes are made from weathering steel, aka Cor-Ten.  This has a lot of copper in it.  Copper oxide in the joint means no weld possible.  The ones marked HC are usually very low in copper (and carbon, ~0.3%) 

Note that the specs say if the buyer wants the copper added, they can specify the head be stamped "CU."  What is important here is that it doesn't say they MUST be stamped CU.  If the rust is bloodstain-colored rather than orange or brown, that can indicate (but not prove) copper in the steel.  Sometimes the only way to really know for sure is to have a batch of spikes that simply will not weld.  

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Don't underestimate the homogeneous RR spike knife. Some of them have the magical ability to stop an army tank. 

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The coaxial machine gun on the tank is very effective in stopping opponents armed with spike knives......if not, the main 120 mm smoothbore gun will. You may want to come up with an alternate testing method. I am sure there will suggestions to follow!

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Ah, but the clever ninja who can arrange for the knife to get into the treads of the tank is a formidable opponent and I think we have seen that technique demonstrated.

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