Phase field investigation on solidification cracking susceptibility in the molten pool under different anisotropy
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摘要: 采用相场法模拟研究了各向异性对合金焊接凝固裂纹敏感性的影响规律. 结果表明，随着各向异性强度的增加，枝晶尖端变得更加稳定，不易形成侧枝，枝晶间不易形成桥接，容易形成较长的液相通道. 当各向异性强度较大时，金属熔体难以通过长的液相通道对受拉位置进行补给，因此容易形成裂纹. 基于相场模拟结果，计算了凝固裂纹敏感性指数
$\left|{\rm{d}}T/{\rm{d}}{\left({f}_{{\rm{s}}}\right)}^{1/2}\right|$ ，发现各向异性强度较大时，$\left|{\rm{d}}T/{\rm{d}}{\left({f}_{{\rm{s}}}\right)}^{1/2}\right|$ 的数值也较大，具有较大的凝固裂纹敏感性. 综上，当合金各向异性强度越大时，具有较高的凝固裂纹敏感性.Abstract: Effects of anisotropy on the solidification cracking susceptibility in the molten pool of an Al-Cu alloy are investigated using phase field modeling. The results show that the tip of dendrites becomes stable, side-branches and bridges are difficult to form, and the longer liquid channel is easily formed between dendrites with the increase of anisotropic strength. In the case of large anisotropic strength, welding tensile stresses are difficult to transfer and release through bridging, and the metal melt is also difficult to supply the tensile position through the long liquid channel, so it is easy to form cracks. Based on the simulation results, the solidification cracking susceptibility index |dT/d(fs)1/2| is calculated. It is found that the index is higher when the anisotropic strength is larger. In conclusion, the solidification crack sensitivity is higher when the anisotropy strength is larger.-
Keywords:
- anisotropy /
- solidification crack /
- phase field
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图 2 不同各向异性强度下糊状区晶粒生长和液相通道的模拟结果
Figure 2. Simulated grain growth and liquid channels in the mushy zone under different anisotropic strength
表 1 Al-4.0%Cu合金的物性参数
Table 1 Physical properties of the Al-4.0% Cu alloy
扩散系数，D/(10−9 m2·s−1) 液相线斜率m/(K·(wt.%)−1) 溶质分配系数 k Gibbs-Thomson
系数$ \varGamma $ /(10−7 K·m)各向异性强度 $ {\mathrm{\gamma }}_{4} $ 3.0 −2.6 0.48 2.4 0.01 ~ 0.05 
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