Creep Lifetime Prediction Of Single Crystal Nickel-Based Superalloy

In the paper, based on the [001] orientation, by means of creep texting and microstructure observation under different conditions, investigate creep properties, characteristics ofγ' rafting and microstructure evolution during creep of [001] orientation single crystal nickel-based superalloy. On this basis, useθprojection concept and its modified concept on the creep lifetime prediction of DD3 alloy at same temperature under different stress and the same stress under different temperature. Results are as follows:Withθprojection concept can fit creep curves of [001] orientation DD3 alloy. The results show that,θprojection concept can well describes the process of the first and the second stages of the creep,θ1(1-e-θ21) of 6 equation describes the first stage of strain hardening caused by y'rafting, dislocation's generation, multiplication, piling up, it also describes the second stage of steady creep caused by dislocation's climbing; 03(eθ4'-1) ofθequation describes the third stage of accelerated creep caused by y'coarsening, dislocation cutting through y', destruct y'resistance response capabilities. And establish the relationship between creep equation parameters at 1040℃under different stress and 137Mpa under different temperature. The relationship can be applied for [001] orientation creep lifetime prediction of DD3 alloy under certain conditions.The modifiedθequation can well reproduce three creep stages of DD3 alloy. Its constitutive equations consistent with the strain harden and weaken mechanism of single crystal nickel-based superalloy. This is due to the parameters of creep rate which equations unified. Especially in the third stage of creep, its fitting effect is much better thanθmethod. At the same time, establish the relationship between creep equation parameters at 1040℃under different stress and 137Mpa under different temperature with modifiedθequation. These expressions are linear, in order to ensure the quality of creep lifetime prediction.In terms of creep lifetime prediction,θprojection concept is more suitable for creep lifetime prediction which has longer steady stage and shorter accelerated stage of creep. And the modifiedθmethod is more suitable for creep lifetime prediction which has smaller strain at steady stage and larger strain at accelerated stage of creep. Under the same conditions, the modifiedθmethod reduce a parameters to be determined, it not only reduces the computation, but also avoids the parameter errors on the prediction accuracy.