Elucidation and control of microstructure formation of laser powder bed fusion based on ultrasonic temperature monitoring

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15317
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: KUSANO Masahiro 国立研究開発法人物質・材料研究機構, 構造材料研究拠点, 研究員 (60822583)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 金属積層造形

Outline of Final Research Achievements

An ultrasonic temperature monitoring method for selective laser melting process was established by solving an inverse problem. The ultrasonic propagation behavior during the selective laser melting process was observed by actual measurements and was further reproduced by coupled thermal and ultrasonic propagation analysis. The propagation time of the bottom echo in the ultrasonic waveform increased and decreased periodically with increasing and decreasing temperature in the material and increased as the selective laser melting process progressed. From the measured propagation behavior, the temperature distribution in the process was successfully measured by inverse analysis.

Free Research Field

金属積層造形

Academic Significance and Societal Importance of the Research Achievements

金属積層造形プロセスの温度モニタリングは、これまで高速度カメラや赤外線カメラを用いた方法で実施されてきたが、計測は材料の表面に限定されていた。一方、本研究による超音波を用いた方法では、材料内部を伝搬した弾性波を計測するため、部材内の温度分布を計測することが可能である。実際、金属積層造形プロセス中の材料温度によって、部材の変形や内部欠陥の形成が起こったり、微細組織に影響を及ぼしたりする。そのため、このような材料内の温度を制御することで、より優れた金属積層造形部材を製造を実現できる。