Multiaxial Thermo-mechanical Deformation Behavior of IN 738 LC and SC 16

A study was undertaken to develop an understanding of the fatigue life on IN 738 LC under simple and simulated in-service operating thermomechanical cycling (TMF) in air. The experiments were conducted in the temperature ranges 450 - 950 °C, 450 - 760 °C and 600 - 850 °C. Results indicate that the lives differ with strain-temperature phasing. Diamond cycles gave the longest lives. A life prediction assessment is proposed based on the inelastic work Σ MF σ i j Δe l n i j at Nf. It is, shown that the J 2 theory is applicable to TMF loadings. Initial experiments on single crystal superalloy SC 16 prove that there is a non-uniform strain distribution in the plastic region along the circumference of [001] oriented specimens. These findings must be weighed when performing TMF tests.