Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

Grain Refinement Effect on the Hot-Tearing Resistance of Higher-Temperature Al–Cu–Mn–Zr Alloys

“…Alloy DA6 had a similar nominal Cu content to that of alloy DA7 (Table 1), but intentionally higher Fe and Si. Our previous study of non-grain-refined ACMZ alloys found that those with higher Cu content (7.3 and 8 wt.% Cu, i.e., DA5 and DA7) were the most hot-tearing resistant [2]. Alloy 206 was chosen as a comparative baseline commercial alloy for this study as it is one of the multicomponent Al-Cu alloys used in automotive, aerospace, and other industries where lightweight castings with excellent mechanical performance are required [21].…”

“…In this study, ACMZ multicomponent alloys in which the Cu composition was varied from 5 to 8 wt.% were considered since they exhibit excellent high-temperature mechanical properties [1]. A review of the Cu content effect on hot tearing in Al-Cu alloys indicated that data on hot-tearing susceptibility at Cu contents > 5 wt.% were much less common than that available for alloys with Cu contents < 5 wt.% [2]. The Cu contents of the five alloys (DA1, DA2, DA5, DA6, and DA7) in this study were 4.95, 6.2, 7.3, 8.3, and 8 wt.%, respectively.…”

“…The Cu contents of the five alloys (DA1, DA2, DA5, DA6, and DA7) in this study were 4.95, 6.2, 7.3, 8.3, and 8 wt.%, respectively. The composition of these alloys, which was considered for hot-tearing assessment using a smaller mold with load measurement capability [2], was slightly different than that shown in Table 1. Exact compositions of the five alloys evaluated in this study are shown in Table 1.…”

“…In the third and fourth columns of Table 4, the data is presented for the simple average indicator, M S , and a 4-arm average, M 2-5 , for which the arms 2 through 5 were considered, respectively. For the data shown in Table 4, the average of M S and M 2-5 for five castings were calculated based on Equations (1) and (2). From industrial practice, an overall acceptable hot-tearing index for M S , M A S , is considered to be 3.33 when C i ranges between 0 and 10, which would correspond to a small to moderate crack in each of the six arms.…”