鋼溶接金属部における放射光を用いた溶接過渡応力のin-situ計測

In-situ measurement of transitional stress in welds metal of steel using synchrotron radiation

辻 明宏*; Zhang, S.*; 橋本 匡史*; 岡野 成威*; 菖蒲 敬久  ; 望月 正人*

Tsuji, Akihiro*; Zhang, S.*; Hashimoto, Tadafumi*; Okano, Shigetaka*; Shobu, Takahisa; Mochizuki, Masahito*

本研究では、放射光を用いたin-situ計測技術を用い、SM490Aの溶接金属部における溶接時の過渡的な応力挙動や冷却時の相変態に起因した応力変化を実験的に評価した。その結果、接金属部の冷却過程におけるオーステナイトフェライト変態中の各相に加わる応力の変化挙動をそれぞれ独立して評価し、オーステナイトフェライト変態中にはオーステナイト相に引張応力が、フェライト相に圧縮応力が加わることを確認した。また、相変態開始直後と終了直前には体積比の小さいフェライト相とオーステナイト相にそれぞれ応力集中が生じ、高い引張応力が生じていることを明らかにした。

It is necessary to control weld residual stress which has negative influence on fracture strengths. In structural steel welds, complex residual stress fields are formed due to phase transformation that occur according to the thermal cycles. In this study, in-situ evaluation of phase transformation and transitional stress simultaneously during welding is discussed. In the test using SM490A, after cooling process, stress evaluated by this system showed good agreement with that evaluated by lab X-ray. During austenite to ferrite transformation in weld metal, tensile stress occurred in austenite and compressive stress occurred in ferrite. Moreover, stress concentration was occurred in ferrite phase immediately after the start of phase transformation. Also, stress concentration was occurred in austenite phase just before the end of phase transformation.