Influence of Ni content on hot tearing tendency of Al-5.6Zn-2.5Mg-1.6Cu alloys

A combination of numerical simulation and experimental methods was used to study the influence of Ni content on the hot tearing tendency of Al-5.6Zn-2.5Mg-1.6Cu-xNi （x=0%，0.1%，0.3%，0.5%，mass fraction， the same below） alloys. The hot tearing tendency of the alloy is systematically simulated using the ProCAST software， combining with optical microscopy （OM），scanning electron microscopy （SEM），X-ray diffraction （XRD）， room temperature tensile tests， precipitation phase， stress field， hot tearing index （HTI），and effective stress analysis methods. The hot tearing behavior and mechanical properties of the Al-Zn-Mg-Cu series alloys are systematically studied. The results show that when the Ni content is less than 0.5%， the HTI value first increases and then decreases with the increase of Ni content， and when the Ni content is 0.5%， the HTI value is the lowest. The effective stress at the bottom of the constraint rod also indicates a trend of first increasing and then decreasing with the increase of Ni content， and when the Ni content is 0.5%， the effective stress is the lowest. Compared to the alloy without Ni addition， the alloy with 0.5%Ni addition shows a significant reduction in hot tearing sensitivity， a substantial improvement in mechanical properties， an increase of 54.79% in tensile strength， an increase of 48.49% in yield strength， and an increase of 461% in tensile strain. The numerical simulation results are in good agreement with the experimental results.