Melt pool boundary extraction and its width prediction from infrared images in selective laser melting

作者：Liping Zheng, Qi Zhang, Hong-Zhong Cao, Wenjie Wu, Honglin Ma, Xueping Ding, Jie Yang, Xuan‐Ming Duan, Shuqian Fan · 发表于：Materials & Design · 年份：2019 · DOI：10.1016/j.matdes.2019.108110 · 被引用次数：95 · 研究领域：Additive Manufacturing Materials and Processes、Welding Techniques and Residual Stresses、Additive Manufacturing and 3D Printing Technologies

Selective laser melting (SLM) involves periodic processes of rapid temperature rise and drop, so it is of great interest in evaluating the quality of the melted powders by real-time thermal information. In this study, a LumaSense MCS640 thermal imaging camera in coaxial system, which can track the location of melt pool, was used to real-time monitor the surface temperature during Ti-6Al-4V forming and predict an average melt width by extracting the boundary of the melt pool in each infrared image. The characteristics of the temperature gradient distribution around a melt pool instead of the temperature itself was analyzed, the boundary of a melt pool was determined then by the maximum (or minimum) temperature gradient point in space. Straight melt samples were obtained by a fixed laser scanning direction in this study, the extracted boundaries of the moving melt pool in the direction perpendicular to the laser scanning direction were compared with the measured melt width from a microscope. A best width divergency between the prediction and measurement around 5% is achieved.