SLL tube product for CAB

A family of strong long life tube materials.

All Strong Long Life materials show excellent corrosion performance with lateral corrosion confined to the near surface regions. The brown band, formed during brazing, is the key to producing the excellent corrosion performance compared with conventional alloys. FA7873 (with the highest core Cu content) has the greatest potential difference between the surface and core center in the family. Titanium is added to FA7857 and FA7948 to further improve the corrosion performance by promoting a lamellar corrosion attack.

As-produced grain structure, H24 FA7873.

Chemical composition

Weight %

Mechanical properties

Delivery condition temper and properites

* Value will depend on thinckness, here given for 0.25 mm.

Typical strength and corrosion potential after brazing

Corrosion resistance

All Strong Long Life materials show excellent corrosion performance with lateral corrosion confined to the near surface regions. The brown band formed during brazing is key to providing for the excellent corrosion performance when compared with conventional alloys. FA7873 with the highest core Cu content has the highest potential difference between the surface and core center in the family. Titanium is added to FA7857 and FA7948 to further improve the corrosion performance by promoting a lamellar corrosion attack.

Corrosion of the surface regions on FA7857 after 40 days SWAAT (ASTM G85).

Typical post brazed grain structured

The post-braze grain structure micrographs of the Strong Long Life materials show excellent brazeability characteristics, with no evidence of excessive filler metal penetration or liquid film migration into the core alloys. As expected, the H24 temper material provides for a larger, re-crystallized post-braze grain structure. The brown band is clearly visible in the micrographs.

Post-braze particle and grain structures of FA7873.

 

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