抄録
In the study of materials served at high temperature, the experimental value in creep test and creep rupture test spread in wide range, so it was very important to consider the deviation of the experimental result in engineering for constructions and installations used at elevated temperature.
With 18Cr-8Ni stainless steel, studies mere made with deviation of creep rupture properties such as creep rupture time, elongation and creep rate under stress of 10, 13kg/mm2 at 650°C, and the effect of quenching temperature on creep rupture strength, and size effect of test piece.
The followieg results were obtained:
i) Both creep rupture time and elongation were decreased with increasing quenching temperature, but were almost invariable at above 1100°C.
It seemed that these phenomena were due to precipitation of Cr23C6 on grain boundaries.
ii) Compared to the results in short time testing, the deviation of creep rupture time was smaller and those of elongation and creep rate were larger in long time testing.
iii) Size effect was not recognized between test pieces with 6 and 8mm in dia., however in the results obtained from test piece with 10mm in dia., the deviation or the mean was larger than that in test pieces with 6mm in dia.
