Grain-Size Prediction Model in Aluminum Castings Manufactured by Low-Pressure Technology

Abstract

The grain refinement in a real casting manufactured by Low Pressure Die Casting (LPDC) such as wheels and steering knuckles depends on the grain-refinement potential of the metal and the geometry of the part/process parameters. For this study, the effect of the cooling rate on the AlSi7Mg alloy with different metal qualities in terms of grain refinement was tested. The grain size has been metallographically evaluated in cylindrical test pieces and in the real wheels and steering knuckles manufactured at the Mapsa and Fagor Ederlan foundries. The Thermolan®-Al system has been used to evaluate the nucleation potential in terms of grain size on a standard cup. The grain size has been modeled taking into account the effect of the cooling rate measured in the center of the cylindrical test parts and the different grain-size potential. Different grades of refinement have been tested. The grain size measured in a real casting (wheel and steering knuckle) was used to calibrate the model for a real part in LPDC for different grain-size potential.

Towards the Prediction of Tensile Properties in Automotive Cast Parts Manufactured by LPDC with the A356.2 Alloy

“…Figure 3 shows the different cooling curves recorded from one of the die molds poured to produce the five test castings with diameter and height of 24, 36, 48, 60, and 72 mm [19]. As expected, it is observed that by increasing the diameter of the test casting (lowering cooling rate values) the length of the solidification range increases.…”

“…On the other hand, a test arm casting together with eight industrial castings with different geometries were manufactured in two LPDC aluminum foundry plants. For the first group, eight sets with five different sized cylindrical test castings each, and with same diameter and height (see Figure 1) were manufactured according to the experimental methodology detailed in reference [19]. K-type thermocouples (Heraeus Electro-Nite España, S.L., Asturias.…”

“…In each cooling curve, the criterion t = 0 has been adopted at the maximum temperature registered by the thermocouple. SDAS values measured at any location in a casting can be related to the local solidification time and the cooling rate at that point [19][20][21]. In the present work, t SL parameter has been determined from the cooling curves as t SL = t Eutectic − t AL while CR values have been obtained according to Equation (1) which represents the average cooling rate of primary α-Al dendritic growth [18].…”

“…In the present work, t SL parameter has been determined from the cooling curves as t SL = t Eutectic − t AL while CR values have been obtained according to Equation (1) which represents the average cooling rate of primary α-Al dendritic growth [18]. A second cooling rate parameter (CR 635 ) has been also determined from cooling curves [19] which corresponds to the ratio between the temperature range defined by five values before and after 635 • C value, under the time range defined by such a temperature interval. The average values of the characteristic parameters determined on the cooling curves recorded from each test casting size are listed in Table 4.…”

Mechanical and Thermal Properties of Graphene over Composite Materials: A Technical Review

“…A.I. Fernández-Calvo et al [87] structured a ultra-capacitor with a particular capacitance of 135 F/g in fluid electrolytes, 99 F/g in natural electrolytes, and 75 F/g in ionic electrolytes [88] separately from a synthetically changed graphene material. These versatile electronic capacity gadgets with high power ability and life cycle are likewise called supercapacitors or electrochemical capacitors.…”