Predicting and reducing liquation-cracking susceptibility based on temperature vs. fraction solid
Predicting and reducing liquation-cracking susceptibility based on temperature vs. fraction solid
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作者：
G. Cao;S. Kou
铝焊缝在部分熔化区（PMZ）易发生液化裂纹。这是紧邻熔合区外部的区域，在该区域中由于焊接期间过热而发生液化。采用多组分Scheil合金凝固模型，计算了不同成分钎料的PMZ和焊缝金属在凝固过程中的温度-固相分数（T-fS）曲线。通过检验PMZ凝固过程中是否存在WMfS> PMZfS的有害条件来预测裂纹敏感性，并通过最小化该条件来降低裂纹敏感性。这种方法针对合金7075和2024的完全接头熔透焊缝进行了测试，这些焊缝对液化裂纹非常敏感。在7075的情况下，T-f S曲线预测：1）用填充金属4043、4047和4145制成的焊缝的裂纹敏感性和2）通过4145加额外的Cu消除裂纹。这两种预测都在圆形贴片焊接中得到了证实。类似地，在2024的情况下，T-f S曲线预测了填充金属1100和4043的裂纹敏感性以及通过5356加额外Cu的裂纹消除，并且两个预测都得到了证实。该方法可用于指导选择或开发降低裂纹敏感性的填充金属。
Aluminum welds are susceptible to liquation cracking in the partially melted zone (PMZ). This is the region immediately outside the fusion zone where liquation occurs due to overheating during welding. Using the multicomponent Scheil model for alloy solidification, curves of temperature vs. fraction solid (T-f S ) during solidification were calculated for the PMZ and weld metals (WMs) made with filler metals of various compositions. These curves were used to predict the crack susceptibility by checking whether the harmful condition of WM f S > PMZ f S exists during PMZ solidification, then reduce the susceptibility by minimizing this condition. This approach was tested against complete joint penetration welds of Alloys 7075 and 2024, which are highly susceptible to liquation cracking. In the case of 7075, T-f S curves predicted: 1) crack susceptibility of welds made with filler metals 4043, 4047, and 4145 and 2) crack elimination through 4145 plus extra Cu. Both predictions were confirmed in circular-patch welding. Similarly, in the case of 2024, T-f S curves predicted both the crack susceptibility with filler metals 1100 and 4043 and crack elimination through 5356 plus extra Cu, and both predictions were confirmed. This approach can be used to guide the selection or development of filler metals that reduce the crack susceptibility.