Evaluation on the Accuracies of Sump Depth Measurements during DC Casting Process of 7050 Alloy

Abstract

Present work was carried out to investigate the measurement accuracy of the sump depth for 7050 billet in direct chill (DC) casting process. Three measuring methods were applied: (i) Al-30wt.% Cu melt was poured into the mold at the steady state of the casting attempting to record the profile of billet sump; (ii) two steel rods were vertically dipped into the centreline and the edge of the billet attempting to measure the distances between the solidus and the free liquid surface in the hot-top; (iii) several ordered thermocouples were pre-arranged onto the starting block and they were solidified into the billet as it was cast, and a series of temperature-time curves was recorded after casting. For the purposes of comparison and evaluation, a numerical model based on the same experiment parameters was also built and the simulation results were compared with measured results by above methods. It indicates that the sump depth measured by thermocouples has the best consistency with numerical results. The most accurate method is temperature recoding by thermocouples. The Al-Cu melt pouring method is more accurate than the rods dipping method, and the sump depths measured by later two methods were the positions about the solid fraction (fs) depths of 0.8 to 0.9.

Numerical Simulation and Machine Learning Prediction of the Direct Chill Casting Process of Large-Scale Aluminum Ingots

“…This paper presents a comprehensive study on the evolution of multi-physical fields and grain structures during DC casting solidification processes, providing a reference and method for the optimization of DC casting processes for large-size aluminum alloy flat ingots. Based on the results and discussions, the following conclusions can be drawn: The finite element model used in this manuscript underwent validation against the temperature and sump profiles measured by Yu et al [ 35 ]. The findings indicated that the model used in this study agrees well with the experimental results.…”

“…Yu et al [ 35 ] have conducted temperature and sump profile measurements of 7050 round DC cast ingots with a 300 mm diameter by using thermocouples and pouring Al-30%Cu melt. In order to verify the reliability of the results in this paper, we compared our simulation results with previous experimental measurements and computational results in terms of the temperature distribution and sump profiles.…”

“…Its chemical compositions are outlined in Table 1 . The liquidus for 7050 aluminum alloy is 635 °C, while the solidus is 524 °C [ 35 , 36 ]. The remaining thermophysical parameters were calculated using JMatPro 7.0 and Thermal Calc 2021b software, and were adjusted using data from tensile experiments.…”

Effect of Ultrasonic Melt Treatment on the Sump Profile and Microstructure of a Direct-Chill Cast AA6008 Aluminum Alloy

“…Note that the observed profile does not represent the solidus isotherm. This is because Zn penetration could not go deeper into the fixed solid network (when dendrite coherency has been achieved or solid fraction is around 0.35-0.5) as only inter-dendritic feeding is possible in the mushy zone [15]. Therefore, the observed Zn profiles represent an isotherm at a rather lower solid fraction than the solidus.…”

“…Thus, we expect minimum effect from the depressed solidus with Zn addition on the macroscopic profile. However, the result of temperature profiling using thermocouples is reported to have better accuracy [15]. The grain structure observation shown in Fig.…”