Simulation and Experimental Validation of Secondary Dendrite Arm Spacing for AlSi7Mg0.3 Chassis Parts in Low Pressure Die Casting

Abstract

The structural properties of cast aluminum parts are strongly affected by the solidification in the production process. The solidification dynamics determines the Secondary Dendrite Arm Spacing (SDAS), directly affecting the structural strength of the alloy. Simulation techniques enable the integrated design of chassis parts and their production equipment. However, in order to effectively predict the SDAS formation, the simulation models need to be investigated and calibrated. The present research investigates the SDAS formation models and identifies a robust relation to be used in Design by Simulation phases for AlSi7Mg0.3 parts.

Determination of linear expansion of AlSi10Mg aluminium alloy depending on external conditions during solidification

“…Higher cooling rate will reduce the solidification time, and will also reduce the SDAS parameter which will improve the mechanical properties of the aluminium alloy. This statement is acknowledged by other authors [ 27 , 28 , 29 , 30 ]. As study [ 26 ] describes that SDAS is approximately equivalent to the third root of the solidification time.…”

A method for yield and cycle time improvements in Al alloy casting with enhanced conductivity steel for die construction

“…The process cycle time is considered from the simulation of each sized design case, resulting from the die open condition after complete alloy solidification. The SDAS is calculated with (6) with the coefficients k = 1.852 and n = 0.5735, since these were previously identified for the same material [33]. For example, Figure 7 reports the solidification times and the SDAS in the critical zones for case 3a.…”

“…As a rule of thumb, the SDAS is approximately proportional to the cube root of the solidification time, i.e. the value of n ≈ 0.33, [33,36]. A higher heat removal rate would reduce the solidification time, thus reducing the SDAS and consequently improving the Al alloy strength.…”

“…The grain size of the Al alloy has to be as small as possible in order to obtain good mechanical properties, as the yield strength [30] and the ultimate tensile strength [31,32] are inversely proportional to the square root of the grain size. Thus, for production quality control, the expected Al alloy strength is indirectly verified by measuring the grain size as Secondary Dendrite Arm Spacing (SDAS) on micrographs of polished and etched samples [33]. The SDAS values in critical zones are so important, also affecting the occurrence of defects, that they are usually set as contract specifications with the foundry.…”