| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat exchanger that can extend a period when pitting corrosion is prevented by having pitting corrosion resistance improved.SOLUTION: A heat exchanger tube 4 used in a heat exchanger includes Mn of 0.2-0.3 mass%, Cu of 0.1 mass% or less, and Fe of 0.2 mass% or less, and is made of an alloy composed of balance Al and inevitable impurities. A Zn diffusion layer 14 is formed on the outer surface layer part of the tube wall 13 of the heat exchanger tube 4. The following conditions: T≤200, 0.57≤A≤1.5, D/T≤0.55, and 0.0055≤A/D≤0.025 are satisfied, wherein T [μm] indicates wall thickness of the tube wall 13 of the heat exchanger tube 4, A [mass%] indicates Zn concentration in the outermost surface of the outer surface layer part of the heat exchanger tube 4, and D [μm] indicates maximum depth of the Zn diffusion layer 14. The natural potential of the Zn diffusion layer 14 is lower than the natural potential of a part 15 inner than the Zn diffusion layer 14 in the tube wall 13 of the heat exchanger tube 4. |
