高温对核电工程材料低循环行为的影响研究

Effects of Elevated Temperature on Low Cycle Fatigue Behavior of Nuclear Power Engineering Materials

对核电工程材料 (钛合金 T42 NG与 T2 2 5 NG和主螺栓材料 18Cr2 Ni WA)开展了室温与 35 0℃高温下的低周疲劳性能试验研究 ,获得了各材料单调 R- O本构模型和 M- C寿命估算模型。基于这些模型 ,研究了材料的循环强化与软化规律 ,研究了温度系数λσ,λΔσ和λNf对钛合金静强度、循环强度和低周疲劳规律的影响效应 ;根据温度对寿命的影响系数 λNf与应变幅 Δε/ 2呈线性规律的重要发现 ,提出了考虑温度效应的用于高温低周疲劳寿命估算的 λ- M- C模型 。

WT5BZ]A serial of tensional and low cycle fatigue tests for two kinds of titanium alloy :T42NG and T225NG and for 18Cr2NiWA steel at room temperature and 350℃ are carried out Based on the test results, six monotonic constitutive relationships between stress and strain and six relationships between life N f and strain amplitude controlled are given By three ratio λ σ,λ Δσ and λ Nf of the materials related to the elevated temperature,The influence of the elevated temperature on both monotonic tensional intensity and cyclic intensity of the titanium alloys and on fatigue life of each material is systematically investigated According to the important finding about a linearity relationship between the ratio λ Nf and strain amplitude Δε/2,a new model, or λ M C model for predicting the fatigue life of a exponential material under R=-1 and at an elevated temperature is presented To get the λ M C model,the method that may simplify test and regression is discussed