Research on shear strength of galvannealed coatings

Lap shear test can be generally performed by two kinds of methods. However, the shear strengths measured in both methods (bare and compound sample) may be quite different, which results in some influence on evaluating powdering of galvannealed coating. Samples in uniaxial tensile test are modified to measure their yield stress. The stress–strain curves in tensile test are compared with those in lap shear test. Some factors, which cause shear strengths difference in both cases of lap shear test, are discovered, and the correlation function between them is built up. A parameter is proposed to indicate the powdering of galvannealed coating and its validity is demonstrated by Double Reverse Olsen test.