Reducing Shrinkage Porosity in High-Performance Steel Castings: Case of an ASME B16.34 Gate Valve Body: Part 1—Analysis, Techniques and Experimental Approach

摘要

X-ray computed tomography (CT), in combination with scanning electron microscopy (SEM), has been successfully used to evaluate shrinkage macro- and microporosity levels in a high-performance steel casting. As a test case, a commercially available gate valve body of a Class 300 gate valve based on the ASME B16.34 standard and made from A216 WCB cast steel was analysed, in accordance with the specifications of the standard. The radiographic inspection process, in accordance with ASTM E2868 for digital radiographs, is presented. Both X-ray CT radiographs and SEM micrographs are presented, showing the presence of shrinkage macro- and microporosity, in addition to gas porosity. This study is a precursor to the development of a systematic approach for reducing shrinkage porosity in castings based on the optimisation of design and process parameters that influence porosity formation during solidification.