A New High Strength CAB Evaporator Plate Alloy with High Corrosion Resistance

A new evaporator plate alloy identified as FA7857 has been developed by Sapa. This alloy which is intended for CAB brazing, has been developed to meet the market needs for a material with good formability prior to brazing and a low susceptibility to filler liquid core penetration (sometimes termed LFM) during brazing. The excellent formability in the annealed condition, with an elongation of 26% and an Erichsen cup height of 9.2mm, makes this material highly suitable for pre-stretching prior to evaporator plate forming and brazing. An appropriate pre-stretch is 5% which eliminates the risk of LFM, while improving the uniformity of flow of the filler metal and the final corrosion performance. In SWAAT corrosion tests, brazed samples of the two-side clad sheet remained unperforated after 42 days of testing. These excellent corrosion properties combined with a material yield strength of 53MPa in the post-brazed condition will contribute to the production of a more durable, lighter weight evaporator.