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Old December 24th, 2005, 15:47   #18
ILLusion
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Join Date: Jun 2002
Location: Toronto
Quote:
Originally Posted by "swordforum.com
Traditional Japanese blades have a curve. Some of the curvature may have forged in by the smith, but the majority of curvature comes from the heat treating and quenching process where the edge and the back of the blade cool at different rates such that the steel of the edge is transformed into a harder molecular structure (called martensite) and the blade is softer and tougher (containing pearlite). The martensite crystal is dimensionally bigger than those of pearlite, hence the blade takes on an induced curvature.
http://swordforum.com/swords/nihonto/americanized.html
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