4025 ボロン拡散による経年ボイラ溶接部の寿命延伸効果(S25-5 寿命評価,S25 材料・構造の非弾性挙動・高温強度・損傷評価)

抄録

The surface of welded joint specimens for service material are applied by Boron element, they are taken Heat Treatment at 630℃×1000Hours. We have creep rupture tests them at 630℃×39.2MPa, as a result, Residual Life extends 1.5times, and one of Simulated Coarse, Fine Heat Affected Zone Specimens are 2.5〜4times at 630℃×78.4MPa on creep rupture tests, and They are confirmed that Boron is segregated on the Grain Boundary and trespass to center section of specimen by diffusion, Distance from surface by diffusion is about 1mm, and Verification of the effect on life extension by FEM is about 1.5times, therefore, We consider that life extension of aging boiler by applying Boron is possible.