Copper alloy tube with excellent high-temperature brazeability and manufacturing method therefor

Abstract

Provided is a copper alloy tube that is a drawn tube made from a CuCrZr alloy which suppresses the deterioration of mechanical strength and, in particular, the coarsening of crystal grains even in a temperature zone of a solutionizing treatment, and is thus excellent in high-temperature brazeability, as well as the manufacturing method therefor. The manufacturing method comprises a solutionizing step of heating and holding a tubular extrusion material at a solutionizing temperature of 900° C. or greater and then water-quenching the tubular extrusion material; a main process step comprising a set of steps including a drawing process step of drawing the tubular extrusion material, and an intermediate annealing step of heating at an annealing temperature and then water-quenching the drawn material; and an adjusting process step of further drawing the drawn material and setting average crystal grain sizes in a vertical cross section along an axis as well as a horizontal cross section orthogonal to the axis to 50 μm or less each. The average crystal grain sizes of the vertical cross section and the horizontal cross section are each set to 100 μm or greater and the annealing temperature is set to 900° C. or greater after the solutionizing step, thereby making it possible to make the average crystal grain sizes of the vertical cross section and the horizontal cross section 100 μm or less after the adjusting process step, even if heating is performed at at least 980° C. for 30 minutes followed by air-cooling.