Experimental Analysis of Solidification Cracking Phenomena and Quantitative Evaluation of Welding Procedure Countermeasures Based on Generation Theory Model

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14512
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Osaka University
• Principal Investigator: Yamashita Shotaro 大阪大学, 大学院工学研究科, 助教 (40805107)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: 溶接 / 凝固割れ / 限界ひずみ / 数値計算 / 凝固組織予測

Outline of Final Research Achievements

To understand the solidification cracking behavior in welding, the initiation of the cracks was directly observed, and the strain at crack initiation was evaluated. The boundary conditions for the solidification cracking occurrence were clarified, and the criteria for its occurrence were derived through numerical calculations. Furthermore, since solidification cracking depends on the welding procedure conditions and the formation of the solidification microstructure, an attempt was made to replicate the weld metal microstructure dependent on the welding procedure conditions. The morphology of the weld metal microstructure was reproduced through numerical calculations. In addition to numerical calculations, the changes in the morphology of the weld metal microstructure in actual were experimentally captured. By comparing these experimental results with the analytical results, it was demonstrated that the solidification structure related to the welding conditions can be predicted.

Free Research Field

溶接

Academic Significance and Societal Importance of the Research Achievements

凝固割れ発生のクライテリアについては様々な指標が提案されているが，ひずみを正確に評価された例が少ない中で，本研究において割れ発生ひずみを理論モデル化し，数値計算結果として導出することが可能となった．加えて，溶接施工時の溶接金属形状予測に対して熱弾塑性解析や熱流体解析を駆使する検討がなされている中で，その溶接金属内の組織形成を熱流体解析と結晶成長モデルを連成させることで溶接金属組織形成予測が可能となった．これらの凝固割れ発生に強く影響を与える因子を解析的アプローチにより導出可能となったことは溶接凝固割れ現象の体系化に向けて有意義であると考えられる．