Accelerated tests for the prediction of cut-edge corrosion of coil-coated architectural cladding Part I: cyclic cabinet salt spray

Various accelerated cabinet tests have been used for the evaluation of the cut-edge corrosion of coil-coated architectural cladding. These include the conventional ASTM B-117 method (5% continuous NaCl spray), the standard Pr ohesion test (0.35% (NH4)(2)SO4 + 0.05% NaCl wet/dry spray) as well as modi fied wet/dry spray tests using a relatively dilute artificial acid rain sol ution, shallow specimen incline angles with variations in the ratio of the wet and dry periods. Comparisons with outdoor exposure samples reveal that the B-117 test shows unrealistic corrosion morphology with the most realist ic cut-edge corrosion given by the modified tests. Furthermore, with all ty pes of wet/dry test specimen-to-specimen variation is considerably reduced compared with the continuous salt spray test. In the novel wet-dry tests th e acceleration factor appears consistent with the number of wet and dry cyc les however, the overall acceleration factor is limited and, hence, test ti mes are extended. It is concluded that, over a 1000 h test time, the standa rd:Prohesion test appears to show the best combination of realism and accel eration. (C) 1999 Elsevier Science S.A. All rights reserved.