The influence of metallostatic pressure, grain refiner, and modification on the critical solid fraction (CSF) of cast A380 alloy

In this work, porosity formation with regard to the change in the metallostatic pressure was investigated. Different geometry was generated to simulate the effect of pressure on critical solid fraction. A380 alloy was sand cast. Additionally, the effect of grain refiner and modifiers was also investigated. Samples were subjected to X-ray radiography and density measurement to quantify the pore size and distribution.

Microstructures and Properties of V-Modified A380 Aluminum Alloy Produced by High Pressure Rheo-Squeeze Casting with Compound Field Treatment

The melt of V-modified A380 alloy aluminum alloy was treated by compound field of ultrasonic vibration (UV) and electromagnetic stirring (ES) around liquidus temperatures. Then the high pressure rheo-squeeze casting (HPRSC) process was used to produce an ingot with the alloy melt obtained. The results indicate that the polygonal Si2V phase is precipitated after adding vanadium to the alloy. With the increasing of V content from 0 to 1.05%, the average length and volume fraction of β-Al5FeSi phase is decreased to 30 μm and 1.44%, respectively. The refinement effects of UV, ES, and UV-ES compound field on the microstructure of the gravity casting alloy are as follows: UV-ES > UV > ES. When the pressure is increased from 0 to 400 MPa, the size of primary α-Al is decreased gradually, the morphology of β-Al5FeSi phase is changed from an acicular to a fine fibrous-like one, and the polygonal Si2V phase is refined to fine particle with an average grain diameter of about 8 μm. The ultimate tensile strength (UTS), yield strength (YS), and elongation of the alloy without V are lower than that of the alloy with 0.7%V under the same pressure. When the pressure is 400 MPa, the UTS, YS, and elongation of T6 heat-treated HPRSC alloy with 0.7%V are 301 MPa, 182 MPa, and 3.3%, respectively. With the decrease in the length of β-Al5FeSi phase, the quality index of the HPRSC alloy is increased.

Study on refine and morphology change of AlFeSi phase in A380 alloy by K addition

Aluminum-Silicon (Al-Si) alloys are one of the most widely used aluminum alloys. But iron can severely deteriorate the mechanical property of Al-Si diecasting alloy because its presence leads to the precipitation of different AlFeSi intermetallic phases which damage the ductility of alloys. Thus controlling the fraction and morphology of AlFeSi phase, especially the β-AlFeSi phase is important way to refine the ductility of Al-Si die casting alloys. In this article, K element was added into A380 alloys to study the effect of K on the morphology change of AlFeSi phase. The results show that a certain level of K addition 0.05-0.1 wt% will refine β-AlFeSi and transform β-AlFeSi phase to α-AlFeSi. In addition, K addition can better refine AlFeSi at high ccoling rates. The mechanism of refinement of K on AlFeSi phase is analyzed.

Effect of Flow State of Pure Aluminum and A380 Alloy on Porosity of High Pressure Die Castings

Air entrapment defects prevent the heat treatment from improving the mechanical properties of die castings, which limits the die casting of high-performance components. The flow pattern of the filling process is complicated and experimental analysis is difficult in thin-walled complex die castings. In this study, we constructed a shock absorption tower to observe in real-time the filling process of pure aluminum and A380 aluminum alloy at different fast injection speeds. The degree of breakup of pure aluminum was larger than that of A380 during the filling process, which caused the porosity of pure aluminum to be greater than that of the A380 at each observation position. Re-Oh diagrams explained the difference in porosity between the two metals. The porosity in different regions was closely related to the flow state of aluminum liquid. In addition to porosity measurements, we specifically analyzed the relationship between the porosity of the flowback zone, the final filling zone, and the near-tail zone of cylinder. At the same injection velocity, the porosity at flowback zone was greater than that at the final filling position, the porosity at final filling position was larger than that at the near-tail zone of cylinder, and the final filling position changed as the injection velocity changed.

Effect of Erbium Addition on the Microstructure and Mechanical Properties of Aluminium Alloy

The effect of rare earth metal erbium (Er) modification on the microstructure and mechanical properties of aluminium alloys (A380) were investigated using Optical Microscope (OM), Scanning Electronic Microscope (SEM) attached with Electron Dispersive Scanning (EDS), Vicker’s hardness test and Ultimate Tensile Test (UTS). The results show that the addition of Er reduces the size of the silicon particle and improve mechanical properties of the aluminium alloy. In addition, by adding 0.1 wt. % of Er, the mean area (μm2) and aspect ratio value decreased. The coarse plate like existed in the unmodified alloy transformed into fine particle and short rod. The mechanical properties were investigated by using tensile test and Vicker’s hardness test. The ultimate tensile strength test shows that the tensile and the elongation increased 1.32 % and 9.1 % with 0.1 wt. % Er content of the aluminium alloys, respectively. The hardness improved from the addition of 0.1% Er aluminium A380 alloy.