Experimental Investigation on the Effect Due to Mould Vibrations on Mechanical and Metallurgical Properties of Aluminum Alloy (A-1050)

In the current research work performed, the consequences caused in the casting aluminum alloy specimen due to mechanical mould vibrations are examined. Mould vibration throughout the casting provides decreased rate of shrinkage, good morphology, surface finish and lesser probability of hot tear. In this research work, the effect of mould vibration during solidification of Aluminum A-1050 alloys for dissimilar values of wavelengths at a permanent pouring temperature has been investigated to understand the modification in microstructure and mechanical properties after casting. The Al A-1050 casting has been made in a metal mould with different vibrations. The frequencies are varied from 15Hz to 50 Hz during the casting process. A casting has been made with different vibration as well to compare the results of castings with vibration frequencies. The experimental outcomes exhibited substantial grain refinement and significant increase in tensile strength and hardness of the castings with mechanical mould vibration during the duration and after solidification.

Optimizing the Microstructure and Mechanical Properties of Vacuum Counter-Pressure Casting ZL114A Aluminum Alloy via Ultrasonic Treatment

The effect of ultrasonic temperature on density, microstructure and mechanical properties of vacuum counter-pressure casting ZL114A alloy during solidification was investigated by optical microscopy (OM), scanning electron microscope (SEM) and a tensile test. The results show that compared with the traditional vacuum counter-pressure casting aluminum alloy, the primary phase and eutectic silicon of the alloy with ultrasonic treatment has been greatly refined due to the dendrites broken by ultrasonic vibration. However, the refining effect of ultrasonic treatment on vacuum counter-pressure casting aluminum alloy will be significantly affected by ultrasonic temperature. When the ultrasonic temperature increases from 680 °C to 720 °C, the primary phase is gradually refined, and the morphology of eutectic silicon also changes from coarse needle-like flakes to fine short rods. With a further increase in the ultrasonic temperature, the microstructure will coarse again. The tensile strength and elongation of vacuum counter-pressure casting ZL114A alloy increases first and then decreases with the increase of ultrasonic temperature. The optimal mechanical properties were achieved with tensile strength of 327 MPa and the elongation of 5.57% at ultrasonic temperature of 720 °C, which is 6.3% and 8.2%, respectively, higher than that of alloy without ultrasonic treatment.

New high-strength casting aluminum alloy based on the Al–Zn–Mg–Ca–Fe system without requirement for heat treatment

The paper substantiates the composition and prospects of using high strength Al–Zn–Mg–Ca–Fe casting aluminum alloy without heat treatment based on the study on the structure, technological and mechanical properties. Alloys of the base composition Al–5.5%Zn–1.5%Mg (wt.%) jointly and separately doped with 0.5–1.0 % Ca and 0.5 % Fe were obtained as the objects of research. Standard casting alloys according to GOST 1583-93: AK12M2, AMg6lch, AM4,5Kd were the objects of comparison. A hot tensile test using a cast test bar was conducted to check the tendency to form hot cracks due to hindered contraction. It was shown that separate alloying with calcium and iron does not contribute to the improvement of crack resistance and adversely affects mechanical properties. Combined alloying with 1 % Ca and 0.5 % Fe improves the hot tearing resistance to the level of the AMg6lch alloy properties. This effect is due to calcium-containing phases of eutectic origin formed and a favorable grain structure created that is free from columnar grains. Iron in the alloy structure is bound in compact Al10CaFe2 phase particles as a result of the non-equilibrium crystallization during permanent mold casting. The formation of this phase allowed to reduce the amount of zinc in the (Al, Zn)4Ca phase and mostly retain the (Al) solid solution composition as evidenced by similar hardness values of the Al–5.5%Zn–1.5%Mg base alloy and Al–5.5%Zn–1.5%Mg–1%Ca–0.5%Fe alloy, and the superiority of the values over the hardness of alloys separately alloyed with calcium and iron. Also the cast hardness of the promising alloy more than 20 HV higher than the cast hardness of commercial cast alloys. The new alloy in the as-cast condition exhibited competitive mechanical tensile properties: UTS ~ 310 MPa, YS ~ 210 MPa, El ~ 4 %.