Correlation between Aging Effects and High Temperature Mechanical Properties of the Unmodified A356 Foundry Aluminium Alloy

Abstract

In this study, the effect of aging on the mechanical properties of unmodified A356 aluminium casting alloy with trace additions of Ni or V was investigated. Trace elements were added in concentrations of 600 and 1000 ppm of Ni and V, respectively. Samples from sand and permanent mould castings in as cast and T6 heat-treated conditions were tested. Tensile tests were performed at both room and high temperature (235 °C). Taking into account the results from both testing conditions, Vickers hardness was measured in order to endorse the hypothesis of artificial aging occurring during high temperature tensile tests. In order to study this effect, a series of specimens was aged at 235 °C for different aging times, and aging curves were plotted. The occurrence of static and dynamic aging was evaluated by comparing hardness values of tensile specimens and aged samples, particularly in the range of 5-20 min, as this range corresponds to the time necessary for pre-heating and testing of the tensile samples. A basic correlation between tensile strength and hardness is also given.

Mechanical Performances of Al-Si-Mg Alloy with Dilute Sc and Sr Elements

“…As for the YS, it shows a mild decreasing tendency in low-temperature and medium-temperature section; however, it appears to be a completely stable phenomenon in high-temperature section. The YS values at 20, 100 and 200 • C are about 180.01 MPa, 181.75 MPa and 180.33 MPa, respectively, indicating that this alloy possesses excellent yield strength stability at the temperature range of 20-200 • C. The elongation (El) increases from 10.9% to 23.63% with the temperature increasing from −60 • C to 200 • C. It is worth noting that the decreased amplitude of UTS is basically the same compared with the result of other researchers [6,10,11,16], and El stabilizes at a higher level, exhibiting that the alloy possesses satisfactory plasticity as well.…”

“…It is known that automotive engines operated at the temperature of up to 200 • C [4], and the service temperature of high-speed train sleeper materials may reduce to −60 • C in northern China [5]. However, Al-Si-Mg alloy will lose its strength above 150 • C [6] and generate low-stress fracture due to local plastic deformation caused by stress concentration at low temperatures [7], leading to the demand for expanding its operating temperature range from −60 • C to 200 • C [8].…”

“…While, up to date limited investigations focused on the YS stability of Al-Si-Mg alloy in a wide temperature range. Giovanni et al reported that the ultimate tensile strength (UTS) and YS decreased by 30.36% and 21.74%, respectively, for the T6 treated A356 alloy which was modified by Ni/V when the temperature increased from 20 to 235 • C [6]. Rahimian et al revealed the role of Zr in Al-Si-Cu-Mg alloy utilized at elevated temperatures, the results showed that UTS and YS of T6 treated Al-Si-Cu-Mg-Zr alloy decreased by 34.04% and 31.18%, respectively [10].…”

How Slight Solidification Rate Variations within Cast Plate Affect Mechanical Response: A Study on As‐Cast A356 Alloy with Cu Additions

“…Vickers microhardness (HV) and Rockwell hardness (HRF) tests were performed over samples corresponding to the bottom, center, and top of the three alloys/castings considered and are presented in Figure 4. HV and HRF measurements do not reveal a clear enhancement in hardness, moving from bottom to top, as expected with reference to the linear hardness-strength relationship reported by Tiryakioglu et al [29] and Di Giovanni et al [30]. Cu content, on the other hand, exerts a prominent in uence in increasing the hardness response of this alloy from 60 HV to 90 HV in Cu0 and Cu1, respectively.…”