ABSTRACT The solidification cracking susceptibility of aluminium alloys 2024, 2219, 6061 and 7075 was evaluated recently by the transverse motion weldability test (the lower sheet moved in the transverse direction of lap welding to cause cracking). The tested welds were analysed in the present study. Their transverse cross-sections showed wide backfilled cracks in 2219 (least susceptible) and narrow open cracks in 6061 (most susceptible). Their fracture surfaces showed continuous eutectic in 2219 and discontinuous eutectic in 6061, consistent with the less backfilling in 6061. T was plotted against (fS)1/2 (T: temperature; fS: fraction solid) to explain the differences. The critical local strain rate near the crack was estimated, significantly lower in 6061 than 2219 and consistent with the higher crack susceptibility of 6061.

中文翻译：

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液体回填在减少铝焊缝凝固裂纹中的作用

摘要 最近通过横向运动可焊性试验（下板沿搭焊横向移动导致开裂）评估了 2024、2219、6061 和 7075 铝合金的凝固开裂敏感性。在本研究中对测试的焊缝进行了分析。它们的横截面在 2219（最不敏感）和 6061（最容易）中显示出较宽的回填裂缝和狭窄的开放裂缝。它们的断裂面在 2219 中显示出连续共晶，在 6061 中显示出不连续共晶，这与 6061 中回填较少的情况一致。将 T 与 (fS)1/2（T：温度；fS：固体分数）作图以解释差异。估计裂纹附近的临界局部应变率，6061 明显低于 2219，与 6061 较高的裂纹敏感性一致。