加载频率及焊接缺陷对5A06铝合金TIG焊接头超高周疲劳性能的影响
Effects of loading frequency and welding defects on very-high-cycle fatigue properties of 5A06 aluminum alloy TIG welded joints
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摘要: 采用自行研制的TJU-HJ-I型超声疲劳试验系统及常规疲劳试验系统对5A06铝合金TIG焊接头的疲劳性能进行研究. 通过扫描电子显微镜对超声疲劳断口形貌进行观察. 结果表明,加载频率对5A06铝合金TIG焊接头的疲劳性能影响不大,超声疲劳试验结果可以用于表征其机械结构长期使用的安全性. 当焊接接头中气孔作为裂纹源时,不考虑气孔尺寸,气孔中心距表面的距离越近,疲劳寿命越低. 焊接过程导致的焊缝内的夹杂类型为氧化物,其密度较大,对疲劳性能产生影响.Abstract: Self-developed TJU-HJ-I ultrasonic fatigue test device and conventional fatigue test device were used to test the fatigue performance of 5A06 aluminum alloy TIG welded joints. The ultrasonic fatigue fracture morphology of specimen was observed by scanning electron microscope. The results revealed that 5A06 aluminum alloy flush welded joint did not show an influence of cyclic frequency on lifetimes in the high cycle fatigue regime. And ultrasonic fatigue test results can be used to characterize the safety of long-term used mechanical structure. It was proved that if the location of the pore was with small depth from the surface, a small value of fatigue cycles would be got without considering the size of the pore. The inclusions in the weld introduced during the welding process were oxide. The oxide had large density and had effect on fatigue properties.
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Keywords:
- welded joints /
- very-high-cycle fatigue /
- defect
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