Hot Tearing in Aluminium-Copper Alloys

For many aluminium alloys, hot tearing susceptibility follows a lambda curve relationship when hot tearing severity is plotted as a function of solute content. In the past, there has been some difficulty quantifying hot tearing. Traditional methods rely upon measuring electrical resistivity or the number and/or length of cracks in tests such as the ring test. In this experimental program, a hot tear test rig was used to investigate a series of binary Al-Cu alloys. This device measures the load imposed on the mushy zone during solidification. Hot tearing susceptibility was quantified in two ways. The first method involved measuring the load at the solidus temperature (548°C). The second method was to radiograph the hot spot and measure the image density of the cracks. Both methods had advantages and disadvantages. It was found that the results from the hot tear rig correlates with other published data using different experimental methods.