On the influence of process variables on the thermal conditions and properties of high pressure die-cast magnesium alloys

Kim

et al. 2009

Metall Mater Trans A

As a lightweight material, magnesium is being increasingly used for automotive parts. However, due to a hexagonal-closed-packed (hcp) crystal structure, in which only the basal plane can move, magnesium alloy sheets exhibit a low ductility and formability at room temperature. Press forming of magnesium alloy sheets is conventionally performed at elevated temperatures of 200°C to 250°C and thus is known as energy consumed forming. Therefore, in view of an energy saving forming technology, we study magnesium alloy sheet forming by a rotational incremental sheet forming (RISF) at room temperature, where the rotational tool generates local heat of specimen enough to accelerate plastic deformation. The flow curves of the magnesium alloy sheet are obtained and calculated at elevated temperatures, while the yield loci of the magnesium alloy sheet are measured at room temperature. Using RISF, a square cup of 80-mm width, 80-mm length, and 25-mm height is then formed from a magnesium alloy sheet at room temperature. In addition, the strain distribution is obtained and compared with the forming limit curve (FLC) by considering the effect of the tool radius and is found to effectively predict the forming limit of a magnesium alloy sheet in RISF.

Section: Introductionmentioning

confidence: 99%

Study of Forming Limit for Rotational Incremental Sheet Forming of Magnesium Alloy Sheet

Kim

et al. 2009

Metall Mater Trans A

Archives of Foundry Engineering

“…High-pressure die-cast magnesium components are being increasingly used because of their excellent cast ability and the properties that magnesium offers. The high-pressure diecasting of thin-walled components is particularly suitable because of the excellent flow characteristics of molten magnesium alloys [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…The melting of magnesium is also different from other metals because it requires protection against surface oxidation. It should be noted that magnesium and aluminum die-casting alloys also possess different chemical and physical properties, which require modifications in the injection parameters and die design [2][3][4]8]. The lower density of magnesium vs. aluminum signifies that the inertia is lower, and for the same metal pressure a higher flow speed results.…”

Section: Introductionmentioning

confidence: 99%

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Mg-Al-RE Magnesium Alloys for High-Pressure Die-Casting

Braszczyńska-Malik¹

2014

Experimental Mg-Al-RE type magnesium alloys for high-pressure die-casting are presented. Alloys based on the commercial AM50 magnesium alloy with 1, 3 and 5 mass % of rare earth elements were fabricated in a foundry and cast in cold chamber die-casting machines. The obtained experimental casts have good quality surfaces and microstructure consisting of an α(Mg)-phase, Al 11 RE 3 , Al 10 RE 2 Mn 7 intermetallic compound and small amount of α+γ eutectic and Al 2 RE phases.

“…Especially, after the emergence of new numerical approaches associated with inverse heat conduction problems, the interfacial heat transfer coefficient has been shown as a function of casting pressure, injection velocity and initial die temperature [10][11][12][13] . For example, El-Mahallawy et al reported that a further increase after a certain value in the applied casting pressure would scarcely change the thermal field and the heat flux [14] . Guo et al pointed out that the influence of the pressure would only be prominent if the casting step is sufficiently thick for a step-shape casting [15] .…”

mentioning

confidence: 99%

Interfacial heat transfer behavior at metal/die in finger-plated casting during high pressure die casting process

Yu¹,

Liu²,

Cao³

et al. 2017

China Foundry

H igh pressure die casting (HPDC) is extensively used for mass production, due to the high productive efficiency of a desired component in a rapid solidification speed [1,2] . When HPDC molten alloy is injected into a relatively cold cavity of a die, the solidification rate is highly dependent on the interfacial heat transfer behavior in both the die and the molten alloy [3] , and subsequently influences the microstructure and the consequent mechanical properties of the final product [4][5][6][7] . In other words, a proper high cooling rate could favor the formation of fine microstructure in produced castings. Otherwise, too rapid a cooling rate could cause the premature solidification of the molten metal before the filling completion.Many studies have been carried out to investigate Abstract: Heat transfer at the metal-die interface has a great influence on the solidification process and casting structure. As thin-wall components are extensively produced by high pressure die casting process (HPDC), the B390 alloy finger-plate casting was cast against an H13 steel die on a cold-chamber HPDC machine. The interfacial heat transfer behavior at different positions of the die was carefully studied using an inverse approach based on the temperature measurements inside the die. Furthermore, the filling process and the solidification rate in different finger-plates were also given to explain the distribution of interfacial heat flux (q) and interfacial heat transfer . Due to this high velocity, the interfacial heat flux at the end of T 1 could firstly reach a highest value 7.92 MW•m -2 among the ends of T n (n=2,3,4,5). In addition, the q max and h max values of T 2 , T 4 and T 5 finger-plates increase with the increasing thickness of the finger plate. Finally, at the rapid decreasing stage of interfacial heat transfer coefficient (h), the decreasing rate of h has an exponential relationship with the increasing rate of solid fraction (f).Key words: high pressure die casting (HPDC); interfacial heat transfer behavior; metal/die interface; solidification speed; solid fraction CLC numbers: TG146.1