FA7850 is a high performance tube and manifold alloy that is designed to have a high post-braze strength, with additional strength from heat treatment or natural ageing during operations. The FA7850 product is suitable in a controlled atmosphere brazing process, and optimum strength is obtained with a carefully controlled cooling rate after brazing. With a suitable combination of the FA7850 tube, fin and header, the resulting heat exchanger easily exceeds 40 days in SWAAT.
Grain structure after brazing.
Delivery condition temper and properties
Typical strength after brazing
* As brazed.
Typical strength after brazing and ageing
Tensile strength after natural ageing at room temperature and artificial ageing at 100°C and 120°C. Ageing at high temperature gives the material further strength, long holding time (24 weeks) at elevated temperature has not caused any over-ageing (strength decrease) of the material.
Fatigue data, FA7850 + 10 % AA4343 + 10 % FA6815, naturally aged.
Corrosion potential after brazing –710 mV (SCE). Corrosion on FA7850 tube after >40 days SWAAT (ASTM G85) brazed in combination with FA6815 fin. Only superficial corrosion was found.
Gränges has developed the tube slitting process into excellence. This ensures very high quality slit edges on tube strips, which is crucial in order to form and weld tubes with high quality and a high production yield.
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