SUS 304 における粒界クリープ損傷とクリープ特性

概要

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For the purpose of evaluating creep damage, systematic study of creep damage was performed, particularly for grain boundary creep damages by SEM observation and density change measurements. Three different kinds of grain boundary creep damages leading to creep fracture were observed. They are cracks formed at triple points at higher loading stress, grain boundary cavities at medium stress and cracks at sigma/austenite interface at lower stress. Both the grain boundary cavities and the cracks at sigma/austenite interface comence to form at comparatively low creep strain (0.1-0.6%) at the steady-state creep stage (t/t_r : 0.2-0.4). The increasing feature of cavity volume with creep time corresponds to the creep curves. Precipitation of AlN associated with sigma phase on grain boundary leads to early formation of the cracks at their interface. In this case, the volume of the cracks increases considerably in the accelerating creep stage and constitutes a main component of the creep strain. The rapid increase in the volume causes the transition from the steady-state to the accelerating creep stage.
社団法人日本鉄鋼協会の論文
1988-10-01