Aluminum alloy strip manufacturing process for the manufacture of brazed heat exchangers
View Patent ↗The invention relates to a process to manufacture a clad strip, preferably <1.5 mm thick, intended for the manufacture of brazed heat exchangers, comprising: casting a plate of core alloy comprising (% by weight): Si<0.8, Fe<0.8, Cu 0.2-0.9, Mn 0.7-1.5, Mg<0.4, Zn<0.2, Ti<0.1, other elements <0.05 each and <0.15 in total, the remainder aluminum, homogenizing the plate between 550 and 630° C. for at least one hour, cladding one or two sides of the plate with a brazing aluminum alloy, preferentially containing 5 to 13% silicon, hot rolling followed by cold rolling of the plate to a thickness close to a final desired thickness, recrystallization annealing of the strip between 300 and 4000 C., strain hardening of the annealed strip to obtain a permanent deformation between 2 and 10% and to obtain the desired final thickness.
1. A process to manufacture a clad strip, suitable for use in the manufacture of brazed heat exchangers, comprising:
casting a plate of core alloy comprising (% by weight):
Si<0.8, Fe<0.8, Cu 0.2-0.9, Mn 0.7-1.5, Mg<0.4, Zn<0.2, Ti<0.1, other elements <0.05 each and <0.15 in total, the remainder aluminum,
homogenizing said plate for at least one hour,
cladding one or two sides of said plate with a brazing aluminum alloy,
hot rolling followed by cold rolling of the plate to a thickness close to a desired final thickness,
recrystallization annealing the strip to form an annealed strip,
strain hardening the annealed strip to obtain a permanent deformation between 2 and 10% to obtain said desired final thickness.
2. A process according to claim 1 , wherein the core alloy comprises less than 0.1% total of Cr, Zr, Hf, V and Sc added together.
3. A process according to claim 1 , wherein the brazing aluminum alloy comprises 5 to 13% silicon.
4. A process according to claim 1 , wherein the homogenizing is conducted for at least 3 hours.
5. A process according to claim 1 , wherein the strain hardening of the annealed strip is performed with a permanent deformation between 4 and 8%.
6. A process according to claim 1 , wherein the strain hardening of the annealed strip is performed by skin-pass type rolling.
7. A process according to claim 1 , wherein the strain hardening of the annealed strip is performed by tension leveling.
8. A process according to claim 1 , wherein said process produces a clad strip that shows a perforation-free service life in a SWAAT test according to ASTM G085 standard of over 40 days.
9. A process according to claim 1 , wherein the clad strip is less than 1.5 mm thick.
10. A process according to claim 1 , wherein each of Cr, Zr, Hf, V and Sc, if present, are present in an amount of not greater than 0.01% each.
11. A process according to claim 1 , wherein each of Cr, Zr, Hf, V and Sc, if present, arc present in an amount of not greater than 0.1% in total.
12. A process according to claim 1 , wherein said homogenizing is conducted between 550 and 630° C. and said recrystallization annealing is conducted between 300 and 400° C.