Abstract

The paper provides a fractographic analysis of fatigue cracking in D16T aluminum alloy under very high cycle fatigue at a frequency of 20 kHz. The analysis shows that in the range of 2.8 × 10⁸ to 5.1 × 10⁹ cycles to failure, the material reveals cracks on and beneath its surface with their subsurface site developing through intergranular fracture at triple junctions or smoothly faceted transgranular fracture. The main crack develops by shear with the formation of differently oriented facets against which a cascade of oriented and misoriented dimples appears. Such dimples are left by spherical and ellipsoidal particles which are formed, displaced, and intruded into both fracture sides as the crack edges come in contact.

中文翻译：

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D16T铝合金的极高循环疲劳

摘要

本文提供了D16T铝合金在20 kHz频率下极高循环疲劳下的疲劳裂纹的分形分析。分析表明，在2.8×10 ⁸到5.1×10 ^9的 破坏循环范围内，该材料在其表面上和表面下均显示出裂纹，其次表面部位是通过三重交界处的晶间断裂或光滑刻面的跨晶断裂而发展的。主裂纹是通过剪切作用形成的，并形成了不同取向的小平面，在这些小平面上出现了一连串的定向凹坑和错位凹坑。这些凹痕是由球形和椭圆形的颗粒留下的，当裂纹边缘接触时，球形和椭圆形的颗粒会形成，移位并侵入两个断裂面。