Effect of Iron Content on Hot Tearing of High-Strength Al-Mg-Si Alloy

The effect of iron content on hot tearing of the high-strength Al-Mg-Si alloy was systematically investigated. The alloy with higher content of iron resulted in the severe occurrence of hot tearing during direct chill (DC) casting. Mechanical properties of this alloy in which iron content was changed were investigated during solidification using an electromagnetic induction heating tensile machine. Tensile strength and elongation were discussed in relation with solidification progress of which sequence of crystallization, crystallization temperature of formed phases and their crystallized amount were calculated by a thermodynamic calculation software Thermo-Calc. In order to confirm the calculation results of solidification path, a quenching test also was carried out. Furthermore, by comparing the fracture surfaces of the tensile testing sample and DC billet, the temperature range of crack initiation of the alloy was examined. Comparing the temperature range of crack initiation with the crystallization phase and its crystallization order, iron content influenced hot tearing significantly owing to the crystallization behavior of (AlFeMn) in high-strength Al-Mg-Si alloy. [doi:10.2320/matertrans.47.2821

Influence of copper and iron on solidification characteristics of 356 and 380-type aluminum alloys, Materials Transactions 44

The influence of copper and iron on the solidification characteristics of two major aluminum foundry alloys was investigated. The thermal history during solidification of each sample was recorded and compared with the solidification path calculated from the multicomponent equilibrium and Gulliver-Scheil solidification models. SEM/EDX analysis and optical microscope were used to examine the microstructure of solidified samples. The amount of phases was also calculated from the latter model and compared with the observed microstructure. Binary interaction parameters were used in calculation for their practicality. Results show that the high content of copper and iron suppresses the liquiduses and final solidification temperatures. Moreover, the crystallization of Al 2 Cu and Al 5 FeSi is very sensitive to copper and iron content respectively; Al 2 Cu increases significantly when copper is added while Al 5 FeSi does greatly when iron content is higher

Mechanical Properties of High Strength Al-Mg-Si Alloy during Solidification

Mechanical properties of high strength Al-Mg-Si alloy during solidification have been investigated. Tensile strength and ductility have been measured by using an electromagnetic induction heating tensile machine. The relation between solid fraction and temperature was calculated by the Gulliver-Scheil model applied with the thermodynamic data-base Thermo-Calc for multi-component system, and its validity was confirmed, comparing with the experiment. Zero Strength Temperature (ZST) and Zero Ductility Temperature (ZDT) were evaluated and correlated with the corresponding solid fraction. Furthermore, the capability of the high temperature tensile test to apply to the break-out of direct chill (DC) casting was examined, comparing the breaking section of the tensile test sample with that of DC billet. Main conclusions are as follows