Modelling creep of single crystal CM186LC alloy under constant and variable loading

This paper investigates the creep behaviour of 0 0 1 oriented single crystal (SX) alloy CM186LC, a nickel base superalloy for gas turbine directionally solidified blade applications. At the explored temperatures of 800 and 900 oC and at stresses relevant to service, the creep curves of this class of alloys are dominated by a long accelerating "tertiary" stage. This stage was modelled through a damage parameter being proportional, as a first approximation, to the creep strain. The proposed differential equations can interpolate the constant load tests and they also show a natural capability to predict the effect of step changes in load and temperature on the creep behaviour of the alloy, without appealing to arbitrary strain or time hardening rules