Discussion
Yield stress decreased gradually to 500°C and decreased abruptly above 600°C. Elongation decreased to 400°C,
was the minimum at 400°C, and increased above 400°C. These tensile properties were same trend irrespective of
metallurgical change. Cyclic softening during low cycle fatigue was same trend with temperature, strain range, heat
treatment, and welding as cycles increased. Cyclic softening was not much different with temperature to 500°C but
cyclic softening was high at 600°C. Cyclic softening increased greatly to about 250 cycles and increased gradually
above this cycle. Amount of cyclic softening increased as yield stress increased.