抄録
In this investigation we studied the effect of Ammonia Gas atmospher on the torsional creep strength of 18-8 stainless steel bars austenized, or then after twisted to 0.128π/cm at -60°-600°C, and found that the creep strength at 500°C and 600°C in Ammonia Gas was considerably smaller than the creep strength in air, and the decrease due to gas of creep limit for a mean creep rate of 4×10-4%/hr during 75 to 100hr was about 34% for 500°C and 23% for 600°C. In the creep specimens tested in Ammonia Gas a hard nitrized case of 0.16-0.25mm in thickness was formed and many fine cracks were produced in the surface of the case during creeping.
