|
Of [001] orientation DD3 single crystal nickel-base superalloy tensile creep performance tests under different conditions and tissue morphology observation, study the creep performance characteristics of the alloy, γ 'phase-shaped raft characteristics and its evolution during creep. On this basis, the θ the innuendo equation and its modified to predict the creep life of the alloy under different temperature conditions of the different stress in the same temperature and the same stress. The research results are as follows: θ mapping method [001] orientation DD3 alloy creep curve fitting, the results show that the, θ innuendo equation well described by the first and second phases of the of DD3 alloy creep process, equation in θ1 (1-e-θ2t) is mainly described by the shaped Laval, dislocations, dislocations proliferation dislocation pile deformation due to hardening of the first stage and by the dislocation climb caused the steady state creep stage, ie creep second stage; θ3 (eθ4t-1) then is mainly described by the γ 'phase is further roughened and bit wrong cut Ah' phase, damage γ 'punch head to resist the strain capacity and other factors, causing a third stage creep acceleration. Calculated by fitting, established 1040 ℃, different stress and 137Mpa, under different temperature conditions, the of θ insinuate equation parameters relational expression. Apply the relationship under certain conditions [001] orientation DD3 alloy creep life prediction. The correction θ the innuendo equation comprehensive reproduce the three stages of the process of DD3 alloy creep constitutive equation to meet the the of DD3 alloy creep process of strain hardening and strain weakening mechanism. This equation unified characterization of creep rate parameters, especially in the third stage of creep, the fit is better than θ mapping method. Meanwhile, given 1040 ℃, the different stress 137Mpa, under different temperature conditions, the relational expression for each parameter in the the correction θ insinuate equation. These expressions broadly are linear, and thus be able to ensure the accuracy of the creep life prediction. Creep life prediction, θ mapping method is more suitable for the creep characteristics of steady creep longer, to accelerate creep shorter alloys; correction θ innuendo rule is more suitable for the steady state less strain, acceleration creep The stage should Variables larger alloys. Under the same conditions, the the correction θ mapping method compared with θ mapping method to reduce an undetermined parameters, not only reduce the amount of calculation, and avoid the parameter errors of prediction accuracy.
|