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Strain-controlled low-cycle fatigue tests of solution-annealed Incoloy 800 were performed at temperatures of 538°, 649°, 704°, and 760°C using axial strain rates of 4 × 10 and 4 × 10 sec. A few hold-time tests were also performed to indicate a noticeable reduction in fatigue life at hold times of 10 and 60 min. A comparison of these fatigue data with similar results for AISI 304 stainless steel indicates essentially identical behavior. An extensive study is made of the cyclic stress-strain behavior of Incoloy 800 and the relationship between the cyclic strain-hardening exponent and fatigue behavior is confirmed. Exponents on N in the elastic and plastic strain range terms of the total strain range equation are identified and compared with those used in the Universal Slopes equation. [ABSTRACT FROM AUTHOR]

Testing procedures are reported for lowcycle-fatigue experiments on hydraulic fatigue machines operated with closed-loop servocontrol of the strain in inductively heated test specimens of the hourglass type. Typical equipment performance data and fatigue-test results are presented. [ABSTRACT FROM AUTHOR]