CHARACTERIZING THE MICROSTRUCTURE OF A GTA WELD IN-PROCESS USING HIGH-SPEED, HIGH-MAGNIFICATION, DIGITAL IMAGING

摘要

A high quality zoom lens and a high-speed CCD camera have been used to image gas tungsten arc (GTA) welds in stainless steel. Both the trailing (solidifying) edge and the leading (melting) edge of the weld pool have been observed. A number of solidification phenomena have been captured including: dendrite growth, melting, and weld ripple formation. Significant information about the evolution and structure of the solid-liquid interface can be extracted from these videos using computerized image analysis techniques. This information can be directly related to the microstructure of the finished weld. Video clips will be presented, techniques for extracting microstructural information from those clips will be discussed, and the extracted information will be related to the microstructure of the finished weld.