Abstract
In the previous report (Tetsu-to-Hagané, 47 (1969), p. 1697-1704), the author first dealt with high temperatufe load-carrying ability and structural stability of the various gamma -prime precipitated alloys of which the matrix compositions were varied from Ni-base alloys to Fe-base alloys.
In this investigation, the author studied the influence of structural stability and Ti/Al ratio of the various gamma-prime precipitated alloys containing Fe. The matrix composition of specimens were varied in Ni content with the alloys with 0% and 20% Co.
Ti Al contents were determined to be constant at 4% and Ti/Al ratios were selected in the two series of 1/1 and 4/1.
The specimens used for age-hardening, short-time tensile and high -temperature creeprupture tests and X-ray diffraction test were made from a hot-forged bar (16mm diam.) by a double-melting process consisting of vacuum-induction and vacuum-arc methods.
Regardless of the difference in the Ti/Al ratio, age-hardening and high-temperature strength properties were remarkably improved, as the Ni content in the matrix composition was ncreased.
However, age-hardenability and high-temperature strength properties of alloys with a ratio Ti/Al =4/1 were superior to those of alloys with a ratio of Ti/Al =1/1.
The deterioration of high-temperature characteristics in Fe -base alloys with ratios of Ti/ -1/1 were principally caused by the precipitation of massive. β-phases.
It was found that the Ti/Al ratio should be selected to 4/1 preventing the precipitation of massive. β-phase in Fe-base alloys.
