Microstructural analysis of cracked steam drum plate during fabrication process

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The understanding in the fracture mechanisms of the steel plate cracked during the fabrication is of paramount importance for the improvement of the fabrication process for the pressure-containing vessels like steam drum. This article presented the microstructural analysis of the fractured steam drum plate during the fabrication process. The analysis involved visual inspection, chemical analysis, micrograph study, tensile test, and impact test. Results exhibited that the failure of the steel plate was related to the brittle fracture, initiated from the notch, and propagated in the transverse direction perpendicular to the rolling direction. The formation of martensite was found in the affected area, which lowered the crack resistance of the steel plate. The cold worked conditions of the steel plate were induced by the pre-bending process and subsequently facilitated the fracture propagation. It is advised to conduct grinding process to remove the notch and the heat affected zone. Warming the steel plate to be significantly above 0oC is also suggested to perform prior to the fabrication process.