报告题目： Quality Assured Additive Manufacturing of Metallic Materials
Recently Additive Manufacturing (AM) has been hailed as the “third industrial revolution” by Economist magazine [April-2012]. Precision of the product manufactured by AM largely depends on the on line process diagnostics and control. This paper describes paradigm-shifting approach for manufacturing Metallic alloy single crystal and polycrystalline components by Laser Based direct writing and sophisticated on-line diagnostics with close loop control to monitor and control the material properties of the parts during fabrication. Our “Certify as you build” approach provide high level of reliability and robustness in manufacturing in general, thereby minimizing costly production downtime and rejection rate.
The monitored signal includes the surface thermal radiation and the plasma spectrum generated during the laser-material interaction. Correlations have been developed successfully for in-situ detection of temperature, composition, defect and Phase transformation for both polycrystals and single crystal nickel-based super alloys. Due to the multitude of variables involved in the AM process, starting from process parameters to input materials, quality need to be interrogated continuously. Otherwise any defect in the single crystal growth would be accumulated and one will reach the point of no return, at the expense of valuable materials, labor and time. Defect accumulation is also a major problem for Poly-crystalline materials. Therefore, in-situ defect and properties detection is critical to accompany materials fabrication. This in situ diagnostics has the potential to change the way laser processing is practices presently.