CTOD Behavior of Steel Weld with 500 MPa Class Strength and HAZ-CTOD Characteristics of Newly Developed Low Al-B-N Steel

概要

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Recently, there is an increasing demand for a steel with sufficient CTOD characteristics in weld as the steel for offshore structures and low temperature storage tanks to seccure the safety of these structures against brittle fracture. Although it is well known that CTOD behavior of steel weld is fairly often dominated by the Local Brittle Zone (LBZ) inevitably existing in the weld, the subsiance of LBZ and its quantitative influence on CTOD behavior have not yet been fully clarified. In this study, the substance of LBZ and its characteristics are basically investigated and quantitative correlation between LBZ and CTOD behavior in actual weld is made clear with regard to weld thermal histories. Furthermore, the dependance of LBZ toughness on the kind of steel is clarified from the view-point of microscopic factors such as fracture facet size and M-A constituent. Finally, a newly developed Low Al-B-N steel is introduced as a steel which possesses excellent CTOD property stably in weld HAZ over a wide range of welding conditions with the clarification of its mechanisms from a microscopic point of view.
社団法人溶接学会の論文
1989-10-01