Frequency-dependent fatigue and corrosion fatigue assessment of brazed AISI 304L/BNi-2 joints in air and synthetic exhaust gas condensate
Frequency-dependent fatigue and corrosion fatigue assessment of brazed AISI 304L/BNi-2 joints in air and synthetic exhaust gas condensate
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DOI：
10.1111/ffe.12902
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发表时间：
2018-08
影响因子：
3.7
通讯作者：
A. Schmiedt;L. Lücker;M. Manka;W. Tillmann;F. Walther
中科院分区：
文献类型：
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作者：
A. Schmiedt;L. Lücker;M. Manka;W. Tillmann;F. Walther
由于钎焊组件经常在腐蚀环境中循环加载，因此必须研究接头的腐蚀疲劳行为。根据VDA 230 - 214，在接收状态下和预腐蚀后，对与废气热交换器相关的钎焊AISI 304 L/BNi-2接头进行疲劳测试。此外，在废气冷凝液中的叠加腐蚀疲劳载荷实现使用腐蚀电池。对腐蚀引起的和变形引起的显微组织变化进行了金相评价。测试频率从1到150 Hz的循环变形和损伤行为的影响进行了表征。在统计分析中，确定了接收状态下210 MPa的2·107次循环疲劳强度，失效概率为50%。预腐蚀以及叠加载荷导致疲劳强度降低至22%。一种新的测试策略适用于精确的疲劳和腐蚀疲劳评估。
Since brazed components are often cyclically loaded in corrosive environments, the corrosion fatigue behaviour of the joints has to be investigated. Fatigue tests of brazed AISI 304L/BNi‐2 joints, relevant for exhaust gas heat exchangers, were performed with specimens in the as‐received condition and after pre‐corrosion according to VDA 230‐214. Additionally, the superimposed corrosion fatigue loading in an exhaust gas condensate was realised using a corrosion cell. Corrosion‐induced and deformation‐induced microstructural changes were metallographically evaluated. The influence of the test frequency from 1 to 150 Hz on the cyclic deformation and damage behaviour was characterised. In a statistical analysis, the fatigue strength of 210 MPa at 2·107cycles was determined for the as‐received condition with a 50% failure probability. The pre‐corrosion as well as the superimposed loading lead to a reduction of the fatigue strength down to 22%. A novel test strategy is suitable for precise fatigue and corrosion fatigue assessments.