The Nichirin sword replicas in this collection are constructed from 1045 carbon steel, which contains approximately 0.45% carbon by weight. This places it in the medium-to-high carbon range - hard enough to hold a finished edge geometry and take a polished or colored surface treatment, yet workable enough that the blade resists the brittleness common in harder alloys like 1060 or T10. For display-grade replicas, 1045 is a practical choice because it maintains its shape under normal handling and resists warping over time. The alloy does require periodic oiling to prevent surface oxidation, particularly on uncoated sections of the blade.