Lamellar tearing susceptibility evaluation

Six plates were selected for mechanical testing from those obtained for the study. It was found that materials with low through thickness ductilities (% ZRA) measured in the tensile test showed reduced ultimate tensile strengths. The compression test was shown to be capable of providing a quantitative assessment of the through thickness ductility and hence the propensity to lamellar tearing. The compression test was able to detect inclusion distributions near the surface of the plate that were not detected by ultrasonic inspection. The slice-bend test was also able to detect inclusion distribution near the surface of plates. The Lehigh Lamellar Tear Test (LLTT) revealed that inclusion distributions in a test plate must lie within one inch of the test surface in order for a lamellar tearing type failure to occur in the test. The buttering (weld metal overlay) procedure was evaluated in the LLTT and it was found that buttering had little beneficial effects in preventing lamellar tearing in the Lehigh Lamellar Tear Test (again when inclusion distributions lay near the test surface). Acoustic emission monitoring was employed during the tensile tests, slice-bend tests and the LLTT but it was found that lamellar tearing events could not be discriminated from other failure events occurring in the sample. The results further indicate that at least two different types of tests should be employed for a viable prediction of the propensity of a plate to lamellar tearing.