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本研究获得了关于5456-H117铝合金焊件在大气和在海水中的高周疲劳性能数据,并测定某些因素(表面状态和接头类型)对铝合金焊件疲劳性能的影响。在轴向载荷R=O时获得的数据表明,10~7的周次的海水腐蚀疲劳极限为12千磅/英寸~2(8.27兆帕)。这一极限值明显高于以前用弯曲加载所确立的极限值。本研究还测出,5456-H117铝合金单道焊和双道焊焊件的大气的疲劳性能相近。这就表明,在这些焊件中,冶金因素(诸如再熔、再凝固)的差异以及焊珠几何形状在疲劳性能方面拜不起重要作用。最后,发现表面状态(即:精细抛光的表面与粗糙的机加工表面对比)对5456-H117焊件的腐蚀疲劳性能没有明显的影响。表面抛光并未改进疲劳性能归咎于在焊缝试样中存在着皮下微孔隙,因为这些皮下微孔隙明显地控制着海水环境中的裂纹起始。
This study obtained high-cycle fatigue properties of 5456-H117 aluminum alloy weldments in the atmosphere and in seawater and determined the effect of certain factors (surface condition and joint type) on the fatigue properties of the aluminum alloy weldments. Data obtained at axial load R = O show that the fatigue limit for seawater corrosion of 10-7 cycles is 12 ksi / in2 (8.27 MPa). This limit is significantly higher than the limit previously established for bending loading. The study also found that 5456-H117 aluminum alloy single pass and double pass welding parts of the atmosphere fatigue performance similar. This shows that in these weldments, differences in metallurgical factors such as remelting, resolidification, and bead geometry do not play an important role in fatigue performance. Finally, it was found that the surface condition (ie, the finely polished surface compared to the rough machined surface) had no significant effect on the corrosion fatigue properties of the 5456-H117 weldment. Surface finish did not improve fatigue performance due to the presence of subcutaneous microporosity in the weld samples as these submicron microporosity clearly controls the onset of cracks in the seawater environment.