| 摘要 |
PROBLEM TO BE SOLVED: To provide a boiler having a long life by reducing stress damage at a boiler weak point portion such as welding portions of a header and a nozzle neck having a discontinuous shape in which portion high stress happens by forming a melting layer having large ductility. SOLUTION: A boiler of the present invention includes a weak point portion where high stress happens and its configuration is discontinuous and is constructed with a metal product and metal parts that frequently suffer from low cycle fatigue damage and creep damage, but reduces occurrence of any crack due to those damages and lengthens its life by improving extension property thereof by forming its surface with a melting layer by a metal raw material rich in ductility. By forming the melting layer on the surface of the weak point portion happening of any crack due to stress damage in the surface of the weak point portion and propagation of the crack are reduced, and further boiler destruction due to crack penetration is prevented to lengthen the life of the boiler. Further, since alteration of a material for preventing any damage from being produced is realized with the formation of the melting layer with a metal raw material rich in ductility, the rise of the boiler cost following the material alteration can be made minimum.
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