Two-Bar Thermal Ratcheting for Alloy 617--Part I: Scoping Tests.

A two-bar thermal ratcheting procedure has been implemented to Alloy 617 at very high temperatures. The procedure is based on two bars tested on two coupled servo hydraulic machines to achieve equal displacement and constant total applied load, mimicking the behavior of a pressurized cylinder subjected to through wall thermal transients. The bars were heated and cooled out of phase to generate thermally induced loading superimposed on a constant mean stress. Scoping test results at slow heating and cooling rates are presented for different mean stresses and thermal histories. [ABSTRACT FROM AUTHOR]