SB-07-3(083) Effect of Microstructural Changes During Creep on The Creep Rate at 823K in Type 304 Heat Resistant Steel(Changes in Microstructure 2)

概要

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The effect of stress on the shape of creep rate - time curves at 823K in type 304 heat resistant steel has been investigated. The stress conditions of creep tests at 823K, stress range from 157MPa to 333MPa are higher than the 0.2% proof stress of the type 304 heat resistant steel. At the stresses higher than 265MPa, creep rate decreases monotonously in a transient creep stage and increases monotonously in an acceleration one, such shape of creep rate - time curve is called as normal type. Contrast to this shape in higher stress range of 333 to 265MPa, the shape of the creep rate - time curve in the medium range from 235 to 196MPa turns to the different one with two local minima due to the early inflection, and that shape of creep rate - time curve was designated as W-type. With further decreasing the stress, early inflection in creep rate - time curve turns to obscure one, and almost disappeared at the stresses lower than 177MPa. This shape of creep rate - time curve was designated as V-type. The main cause of changes in the shape of creep rate - time curve is the occurrence of the early infection in creep rate - time curve. Microstructural observation and changes in hardness have indicated that this early inflection has been caused by the dispersion strengthening precipitation of M_<23>C_6 on dislocations
一般社団法人日本機械学会の論文
2001-06-03