Abstract
Samples of commerical lots of rolled temper beryllium copper C17200 were selected with average surface roughnesses, Ra, of 1 and 5 microinch. Some of the material with 5 microinch Ra was roughened to produce strip with a 12 microincn Ra. These lots of material were cleaned and exposed to laboratory environments at Battel 1 e-Columbus Laboratories. A flowing mixed gas was used to simulate a typical office or warehouse environment and a severe industrial environment tor exposures of 0.5, 1, 2 and 5 d. Other coupons were plated with 20, 50, 100 and 200 microinch of cobalt-hardened gold and exposed to these same environments for j d Profilometry and scanning electron microscopy indicate that the original surface finish of the C17200 was uniform. The corrosion rate of clean, unplated beryllium copper was independent of the Ra over the range of 1 to 12 microinch. The visual appearance of gold plated beryllium copper showed similar corrosion behavior for surface roughnesses of 1 and 5 microinch. Corrosion appeared slightly greater on plated surfaces with an Ra of 12 microinch. Increasing the qold thickness on C17200 reduced the amount of corrosion for gold thicknesses between 20 and 200 microinch. Pore corrosion and creep corrosion from corroded pores were observed for a 5 d exposure in both simulated environments.
