焊接接头低周疲劳性能薄弱区转移

发布时间：2019-05-30 11:39

【摘要】：研究汽轮机焊接转子接头低周疲劳性能薄弱区对转子的安全运行具有重要意义。该文测试了汽轮机低压焊接转子用25Cr2Ni2MoV耐热钢焊接接头低周疲劳性能,统计分析焊接接头低周疲劳性能薄弱区与应变幅之间的关系,采用显微硬度测试和有限元模拟分析薄弱区转移原因。结果表明:低周疲劳试验中宏观裂纹出现于焊缝和热影响区的回火区,当外加应变载荷由大变小时,焊接接头低周疲劳性能薄弱区由焊缝中心区域转移至热影响区的回火区。在大应变外加载荷条件下,热影响区的回火区塑性变形受较大约束,焊接接头整体的塑性应变向焊缝区转移;在小应变外加载荷条件下,焊缝区域始终处于弹性状态,热影响区的回火区大硬度梯度的软硬夹层结构加剧了应变集中程度。
[Abstract]:It is of great significance to study the weak zone of low cycle fatigue performance of steam turbine welded rotor joint for the safe operation of rotor. In this paper, the low cycle fatigue performance of 25Cr2Ni2MoV heat resistant steel welded joint for low pressure welding rotor of steam turbine is tested, and the relationship between the weak zone of low cycle fatigue performance and strain amplitude of welded joint is statistically analyzed. Microhardness test and finite element simulation were used to analyze the causes of weak zone transfer. The results show that the macro cracks appear in the tempering zone of the weld and the HAZ in the low cycle fatigue test. When the applied strain load changes from large to small, the weak zone of the low cycle fatigue performance of the welded joint is transferred from the center of the weld to the tempering zone of the HAZ. Under the condition of large strain applied load, the plastic deformation in the tempering zone of the heat affected zone is greatly constrained, and the plastic strain of the welded joint as a whole is transferred to the weld zone. Under the condition of small strain applied load, the weld area is always in elastic state, and the soft and hard sandwich structure with large hardness gradient in the tempering zone of heat affected zone aggravates the degree of strain concentration.
【作者单位】：清华大学机械工程系;上海电气电站设备有限公司上海汽轮机厂;
【基金】：上海市科学技术委员会科研计划项目(13DZ1101500)
【分类号】：TG407

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