The study of Timken 16-25-6 alloy containg Ti or B was reported in the report (X) (XI) (Tetsu-to-Hagané vol. 43, 1957, No. 5. p. 543-550, No. 7, p. 713-720) of "Study of Heat-Resisting Steel". The report (X) explained precipitation-hardening phenomena of the above alloy. In the report (XI), warm work effect on 16-25-6 alloy containing Ti or B was determined. In this report, the creep test at 650°C was made.
There were four samples with different chemical components. Sample #D5 contained 1.3% Ti, #D6 contained 0.060% B, #D7 contained 0.08% Ti and 0.025% B, and #B11 was standard Timken 16-25-6 that contained 0.13% N. After hot forging, they were solution-treated at 1150°C for 1 hour, and aged at 800°C for 50 hours. After this treatment, samples of measurements for the creep test specimens were machined.
Creep test was made at 650°C for 500 hours with a load of 18kg/mmmm2. Then, each specimen was examined for hardness and observed through a microscope.
Sample #D5, 16-25-6 alloy containing Ti, showed remarkable higher creep resisting properties than standard 16-25-6 alloy and other samples. Standard 16-25-6 alloy, #B11, and sample #D6 showed similar creep curves. Sample #D7 was rather weaker than #B11 and #D6. It was concluded that the addition of Ti effected creep strength; and the addition of B instead of the usual N may prove desirable to keep creep strength at the standard level. But, addition of a small amount of Ti and B was not so effective.
In this report, other age-hardening phenomena in sample #D5, for example, soaked at 650°C after aged at 800°C, was also described.