Copper alloy tube for heat exchanger excellent in fracture strength
The present invention provides a copper alloy tube for heat exchangers which is tolerable to a high operating pressure of new cooling media such as carbon dioxide and HFC-based fluorocarbons, and is excellent in fracture strength, even if the tube is thinned, and a copper alloy tube for a heat exchanger which has a composition having specified amounts of Sn and P, has an average crystal grain size of 30 μm or less and has a high strength of 250 MPa or more of a tensile strength in the longitudinal direction of the tube improves the fracture strength as a texture in which the orientation distribution density in the Goss orientation is 4% or less.
1. A copper alloy tube for a heat exchanger having a fracture strength of at least 42 MPa, wherein the copper alloy tube comprises Sn:0.1 to 3.0% by mass and P:0.005 to 0.1% by mass, the remainder has a composition made from Cu and inevitable impurities, the average crystal grain size is 30 μm or less, and the longitudinal tensile strength of the tube is 250 MPa or more, and wherein the copper alloy tube comprises:
a texture whose orientation distribution density in the Goss orientation is 4% or less, and
wherein the proportion of the low-angle grain boundaries of the inclination angle 5 to 15° in the texture of the copper alloy tube is 1% or more.
2. The copper alloy tube for a heat exchanger excellent in fracture strength according to claim 1 , further comprising:
Zn: 0.01 to 1.0% by mass.
3. The copper alloy tube for a heat exchanger excellent in fracture strength according to claim 1 , further comprising:
less than 0.07% of the total amount of one or two or more kinds of elements selected from the group consisting of Fe, Ni, Mn, Mg, Cr, Ti and Ag.