低炭素鋼溶接熱影響部の靱性試験における荷重低下現象

概要

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The load drop or pop-in phenomenon at the fracture toughness test of the heat affected zone (HAZ) of a low carbon steel has been investigated. Microstructural features such as the size of the bainitic ferrite were varied with the thermal cycles simulating a double pass welding. It is revealed that the initiation of the load drop is not dependent on test temperatures, whereas the arrest of the load drop decreases with the decrease of the test temperature, thus increasing the amount of the load drop. Fractographic examination has revealed that the amount of the load drop scales with the crack length formed by the local brittle fracture. Also, the size and density of cleavage facets increases with the load drop. It is discussed that the temperature dependent amount of a load drop is determined by the ductile linking of cleavage facets produced at bainitic ferrite grains.
社団法人日本鉄鋼協会の論文
1997-05-01