Murray Carter - Forging a Kuro-Uchi Nakiri-bocho Video

[video=youtube;B7Izy9a9m8k]http://www.youtube.com/watch?v=B7Izy9a9m8k[/video]

I thought it was amazing to see him use the recess in his log to knock the scale off the nakiri.
 
Murray is one of my favorite smiths:thumbup: Which is why I am pleading for him to wear safety glasses!!! (pass it on, Somber)

12:05 - Did Murray say he refined grain internally with cold forging? Does he mean that by imparting dislocations, he is creating nucleation points that will recrystalized during the final quench? Perhaps the highly refined, pure Japanese steels could benefit from mechanical refinment(maybe) but modern steels are complex with more internal stresses and anomalies already present. Inducing more stress energy seems unwise. I think that forging at proper temperatures, along with pre-heat treat thermal cycling would accomplish the same, even more consistant results, without all the risks of mechanical methods. Murray has lots of experience, I'm just typing outloud.
 
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Rick Marchand said:
Murray is one of my favorite smiths:thumbup: Which is why I am pleading for him to wear safety glasses!!!
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I'm just an office assistant; he's the guy that's been making knives the same way every day for 24 years. He does wear safety glasses, too, just not through every stage of his knifemaking. That being said, he does understand and appreciates the concern; it is probably the most voiced statement by everyone, but... You make the bed you lie in, you know?

Rick Marchand said:
12:05 - Did Murray say he refined grain internally with cold forging?
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From Murray's book:

A common technique used by Japanese bladesmiths but seldom exploited by western cutlers is the process of cold forging. In simple terms cold forging is the mechanical reduction in the steel's grain size through force when the steel is below normal forging temperatures. Cold forging makes the steel denser. In its extreme, cold forging is done with the steel at room temperature. Amongst metallurgists, the value of cold forging is controversial, because the theory doesn't match up with reality.

Metallurgists argue that while cold forging does work-harden steel, the effects of cold forging are nullified when the steel is later heated to the temperature required for quenching. Further, they argue, cold forging will induce micro fractures in the steel that will eventually cause a hardened blade to fail under duress. I have conducted research that supports the attributes of cold forging in blades, and all highly respected Japanese bladesmiths incorporate the process. Japanese bladesmiths unanimously agree that cold forging enhances cutting performance in blades. In the final analysis, it is difficult to argue with the results.

Here are some thoughts and considerations. Carbon/mild steel laminates seem to really benefit from cold forging and do not generally show evidence of micro-cracking. While I have seen homogeneous blade fracture from too much cold forging, in 16,000 blades, rarely have I seen a laminate blade fail as a result of cold forging. I suspect that the softer outer laminations absort excess force and energy, thus protecting the inner carbon steel from over stress. On the other hand, I have purposely destroyed a laminated blade by cold forging it until the blade fractured. Therefore, the amount of cold forging is a factor that must be understood.

...the blades that I have experimentally destroyed required this procedure to be repeated many more times before the blades would crack. As a general rule, Yasuki White steel can withstand more cold forging than Blue Steel before failure... Again, in order for the student smith to appreciate the process and value of cold forging it must be experienced first hand.
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Bladesmithing with Murray Carter, by Murray Carter, ABS Mastersmith pg. 53-54
 
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I'm going to try and prevent a digression of this thread, and preempt an argument between traditional forgers who cold forge/edge pack the blade, and the metallurgists who disagree based on metallurgical theory and research.

Suffice to say that both camps have their own research and opinions ... and neither will likely change the others mind. Lets not start debating it here.

Murray is a great maker and his knives speak for his skills. I certainly would not argue with his results, whatever the reason or explaination.
 
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Stacy, you can bump this if you like but I can't let this by without comment ! This is the old edge packing grain refinement arguement .Cold working actually makes the steel increase in volume . I've explained it somewhere in detail and I won't repeat it here.
 
That sure is a sweet power hammer he is using

I wonder why he wouldn't just use a full piece of high carbon steel instead of forge welding the tiny piece into the low carbon steel? over all flexibility, preserving the traditional Japanese process, was high carbon steel hard to come by back then?
 
Actually the traditional steel making process produced steels of various carbon content .Some of the swrods would contain three different steels .
 
jonekatt said:
I wonder why he wouldn't just use a full piece of high carbon steel instead of forge welding the tiny piece into the low carbon steel?
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Murray won't make a knife that isn't a laminate or quenched in water, for one. Secondly, the high carbon steel core is forge welded to the mild steel, Gokunan-tetsu, so that the knife has the best of both worlds; a high carbon steel core (hRC ~63-64) to provide a hard cutting edge with a overall structure, or body, that is strong and flexible.
 
I think that he also does the laminate to make things a lot simpler to straighten, since these knives are absurdly thin. I think that's how it worked with his yanagi-ba, at least.
 
Don Nguyen said:
I think that he also does the laminate to make things a lot simpler to straighten, since these knives are absurdly thin. I think that's how it worked with his yanagi-ba, at least.
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For cutting performance thinner is always better, but that yanagi-ba is actually about twice as thick (at the spine) than our standard kitchen knives and measure at ~3.1mm at the Carter stamp. A laminate is certainly easier to straighten than a homogeneous blade. Murray spent a lot more time straightening that blade than what was shown.

source: I filmed the wide-angle shots.
 
Rick and mete,
I agree that the statements about edge packing, and similar cold treatments do not mesh with metallurgical findings. However, I would rather one of you start a new thread to discuss it than to derail this thread. I would gladly join in a discussion on the new thread.
 
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