Abstract: A hot-rolled copper plate consists of pure copper having a purity of 99.99 mass % or greater, the hot-rolled copper plate having an average crystal grain diameter of 40 ?m or less, and a (?3+?9) grain boundary length ratio (L (?3+?9)/L), which is a ratio between a total crystal grain boundary length L measured by an EBSD method and a sum L (?3+?9) of a ?3 grain boundary length L?3 and a ?9 grain boundary length L?9, being 28% or greater.

Abstract: A hot-rolled copper plate consists of pure copper having a purity of 99.99 mass % or greater, the hot-rolled copper plate having an average crystal grain diameter of 40 ?m or less, and a (?3+?9) grain boundary length ratio (L ?3+?9)/L), which is a ratio between a total crystal grain boundary length L measured by an EBSD method and a sum L (?3+?9) of a ?3 grain boundary length L?3 and a ?9 grain boundary length L?9, being 28% or greater.

Abstract: A hot-forged copper alloy part which has a tubular shape, in which an alloy composition contains 59.0 mass % to 84.0 mass % of Cu and 0.003 mass % to 0.3 mass % of Pb with a remainder of Zn and inevitable impurities, a content of Cu [Cu] mass % and a content of Pb [Pb] mass % have a relationship of 59?([Cu]+0.5×[Pb])?64, a shape of the forged part satisfies a formula of 0.4?(average inner diameter)/(average outer diameter)?0.92, 0.04?(average thickness)/(average outer diameter)?0.3, and 1?(tube axis direction length)/(average thickness))?10, a forging material which is to be hot-forged has a tubular shape and satisfies 0.3?(average inner diameter/average outer diameter)?0.88, 0.06?(average thickness)/(average outer diameter)?0.35, and 0.8?(tube axis direction length)/(average thickness))?12, and 0%?(degree of uneven thickness)?30%, 0?(degree of uneven thickness)?75×1/((tube axis direction length)/(average thickness))1/2 in any location in a tube axis direction.

Abstract: A hot-forged copper alloy part which has a tubular shape, in which an alloy composition contains 59.0 mass % to 84.0 mass % of Cu and 0.003 mass % to 0.3 mass % of Pb with a remainder of Zn and inevitable impurities, a content of Cu [Cu] mass % and a content of Pb [Pb] mass % have a relationship of 59?([Cu]+0.5×[Pb])?64, a shape of the forged part satisfies a formula of 0.4?(average inner diameter)/(average outer diameter)?0.92, 0.04?(average thickness)/(average outer diameter)?0.3, and 1?(tube axis direction length)/(average thickness))?10, a forging material which is to be hot-forged has a tubular shape and satisfies 0.3?(average inner diameter/average outer diameter)?0.88, 0.06?(average thickness)/(average outer diameter)?0.35, and 0.8?(tube axis direction length)/(average thickness))?12, and 0%?(degree of uneven thickness)?30%, 0?(degree of uneven thickness)?75×1/((tube axis direction length)/(average thickness))1/2 in any location in a tube axis direction.