熊  茹，张  亮，刘  鸿

（中国核动力研究设计院四所，四川省成都市，610041）

　　摘要：TA17钛合金高周疲劳行为是高效蒸汽发生器设计时需要考虑的重要参数。采用旋转弯曲试验方法完成了钛合金TA17棒材室温及350℃空气中的高周疲劳试验，获得S-N曲线、P-S-N曲线、核岛设备设计用S-N曲线及耐久极限应力，采用扫描电镜观察了断口形貌。研究表明，TA17棒材疲劳数据符合正态分布特性，均值法拟合的S-N曲线显示斜率变化，耐久寿命取为107次，中长寿命区S-N关系具有较好的精度。高温会降低材料的疲劳性能，表现为高温耐久极限应低于室温的耐久极限应力。P-S-N曲线中，耐久极限应力随着存活率升高而降低。取安全系数后，核岛设备设计用S-N曲线中的耐久极限应力已降至100MPa以下。观察到，TA17疲劳行为对试验频率不敏感；设计中要考虑应力形式的影响和转换；断口形貌呈现裂纹萌生、扩展和断裂的特征，高温试验存在氧化现象。与静强度经验公式值及温度敏感性的对比表明，TA17具有较好的抗高周疲劳性能；与设计值相比，TA17棒材低高周疲劳性能明显优于设计规定，表明TA17棒材在工程使用中可保证结构部件的规定寿命。研究结果推动了TA17在核工程中的应用，也可为其他应用提供参考。

　　关键词：钛合金，高周疲劳，S-N曲线，耐久极限应力，断口

　　Study On High Cycle Fatigue Behabior Of Titanium Alloy Ta17

　　Xiong Ru,Zhang Liang,Liu Hong

　　（ Nuclear Power Institute of China, the 4th sub-institute, Chengdu, Sichuan, 610041, China）

　　Abstract:The high cycle fatigue behavior of titanium alloy TA17 is importance parameter for the design and construction of high efficient steam generator. The high cycle fatigue experiments of TA17 rods were performed using bending and rotating tests at RT （room temperature） and 350℃ in air. S-N curve, P-S-N curve, S-N curve for the design of nuclear island components as well as endurance limit stress was obtained, and the fracture morphology was observed by SEM. The results indicate that the experimental data distribution has normalized characterization; S-N curves were fitted by mean value method and the slope of S-N curve changed, the endurance life should be 107 cycles. The S-N correlation is lgS=2.95-0.05lgN at RT and lgS=2.75-0.03lgN at 350℃ respectively, such correlations had high accuracy. Elevated temperature decreased the fatigue property, the value of endurance limit stress is 394MPa （RT） and 339MPa （350℃） respectively. The endurance limit stress decreased when the probability of P-S-N curve increased and then dropped below 100MPa in the S-N curves for nuclear island components design. The fatigue behavior of TA17 is not sensitive to testing frequency, and the influence of stress types should be considered and transferred in design. The fracture morphology presents characterization of crack initiation, propagation and failure, the specimen oxidized at the elevated temperature. TA17 rods have good resistance for high cycle fatigue when compared with the values of empirical equations and temperature sensitivity as well as the design values in Russia which could guarantee the specific life of single high efficient steam generator in the engineering application. The results accelerate the use of TA17 in nuclear engineering, and could provide references for other application of TA17.

　　Key words:titanium alloy; high cycle fatigue; S-N curve; endurance limit stress; fracture

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　　熊茹：littlexiongru@126.com