Effect of the casting process variables on microporosity and mechanical properties in an investment cast aluminium alloy

Abstract

The casting process variables considered were the shell mould preheat temperature, the pouring temperature and the melt hydrogen content. The paper reports progress on a programme to appraise and optimise the mechanical properties of selected investment castings. The in¯uence of shell preheat temperature, pouring temperature and melt hydrogen content on microporosity and mechanical properties were studied in this paper. Shell preheat temperature and melt hydrogen content are the most important process parameters determining the amount of porosity. All three parameters affect the mechanical properties to varying degrees. q

A New Approach to Ultrasonic Degassing to Improve the Mechanical Properties of Aluminum Alloys

“…It is well known that mechanical properties of Al-Si alloys depend on several factors, with particular emphasis to microstructure morphology (Ref 24) and size and distribution of porosities (Ref [25][26][27]. Porosity can be attributed to the inadequate feeding associated to volumetric shrinkage of liquid during solidification and/or to the decrease of hydrogen solubility in Al during cooling.…”

Investigation on controlling the process parameters for improving the quality of investment cast parts

“…For this analysis, hypoeutectic Al-Si 7%-Mg alloy for casting in ceramic shells has been used. On the basis of literature survey [17][18][19][20][21][22], significant process parameters chosen for the study are shell preheat temperature, firing temperature, firing time and pouring temperature to identify their effect on casting shrinkage (both linear and volumetric) and tensile strength of the part produced via IC, while other parameters such as shell thickness, shell drying time, pouring time and cooling condition were kept nearly constant. The range of all the selected input process parameters were decided from the state of the art survey on aluminium alloy castings [23][24][25][26] and trial experiments conducted prior to the final experimentation.…”

Influence of the chemical composition and process parameters on the mechanical properties of an extruded aluminium alloy for highly loaded structural parts

“…It is known that, the mechanical properties of Al alloys are also closely related to the content of alloying elements [9][10][11][12][13][14][15][16][17][18] as well as to the applied process parameters, i.e., casting, homogenization, heating, deformation parameters, heat treatments, etc., [19][20][21][22][23][24][25][26][27][28][29][30]. This means that improving the main mechanical properties of an aluminium alloy, i.e., tensile strength, yield stress, hardness and ductility, is achieved by adding alloying elements, like Mg, Si, Mn, Fe, Cr, etc., since these favour a specific morphology, crystallography and chemical composition of the intermetallic phases in the microstructure [9][10][11][12][13][14][15][16][17][18]31], on the one hand, while with the correct selection of process parameters, the desired characteristics of the intermetallic phases in terms of size, as well as their shape, fraction, distribution, etc., in the final microstructure [19][20][21][22][23][24][25][26][27][2...…”

“…This means that improving the main mechanical properties of an aluminium alloy, i.e., tensile strength, yield stress, hardness and ductility, is achieved by adding alloying elements, like Mg, Si, Mn, Fe, Cr, etc., since these favour a specific morphology, crystallography and chemical composition of the intermetallic phases in the microstructure [9][10][11][12][13][14][15][16][17][18]31], on the one hand, while with the correct selection of process parameters, the desired characteristics of the intermetallic phases in terms of size, as well as their shape, fraction, distribution, etc., in the final microstructure [19][20][21][22][23][24][25][26][27][28][29][30], can be achieved, on the other. Consequently, both strongly affect the properties of the alloy in a complex way.…”