SEDL / STP / STP1371-EB / STP15265S

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

Ziebs, J
Senior Scientist, Federal Institute for Materials Research and Testing (BAM), Berlin,

Meersmann, JFC
Research Scientist, Federal Institute for Materials Research and Testing (BAM), Berlin,

Kühn, HJ
Technical Specialist, Federal Institute for Materials Research and Testing (BAM), Berlin,

Klinglehöffer, H
Research Scientist, Federal Institute for Materials Research and Testing (BAM), Berlin,

Pages: 22    Published: Jan 2000

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Abstract

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 ∑ MF σ^ij Δε^inij at N^f. It is, shown that the J² 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.