Aging Profiles of AlSi7Mg0.6 and AlSi10Mg0.3 Alloys Manufactured via Laser-Powder Bed Fusion: Direct Aging versus T6

Abstract

The artificial aging heat treatments performed directly on as-built and solubilized AlSi7Mg0.6 and AlSi10Mg0.3 samples were characterized and discussed. The analysed bars and billets (height of 300 mm) were manufactured via the Laser Powder-Bed Fusion process on a build platform heated at 150 °C. Therefore, its influence on the as-built samples was studied in terms of mechanical performance variations between the bottom and top regions. Vickers microhardness measurements were performed to obtain aging profiles after direct aging (175–225 °C) and T6 heat treatments and to highlight better time and temperature parameters to optimize the mechanical properties of both alloys. SEM observations were used to characterize the microstructure before and after the heat treatments and its influence on the fracture mechanisms. Generally, the direct aging heat treatments show the same effects on both aluminium alloys, unlike the solubilization at 505 °C followed by artificial aging at 175 °C. The strengths vs. elongation values obtained after the direct aging treatments are better than those exhibited by T6 as highlighted by the quality index.

Development of an accurate “composition-process-properties” dataset for SLMed Al-Si-(Mg) alloys and its application in alloy design

“…It led to higher UTS and EL in alloys along the 0° test direction. However, an interesting observation was also found in some literature reports [12,49,53,54,56,66,[68][69][70]72,74,75] , as shown in Supplementary Figure 1. Under the same preparation conditions, the alloys with a test direction of 90° can also exhibit higher UTS.…”

“…The mechanical properties [including ultimate tensile strength (UTS), yield strength (YS), and elongation (EL)] of the SLMed alloys do not only depend on the compositions [40][41][42][43][44][45][46][47] and processes [48][49][50][51][52][53][54] but also the testing condition [55][56][57][58][59] . Therefore, in order to study the influencing factors affecting the mechanical properties of SLMed Al-Si-(Mg) alloy, the compositions [60][61][62] (i.e., Si and Mg contents), the manufacturing processes (including laser power [63][64][65] , scanning speed [66,67] , scanning spacing [68][69][70] , powder layer thickness [71,72] , hatching space [73] , and rotation angle [74] ), and the testing direction [75,76] should be considered at the same time.…”

“…The data sets of as-built SLMed Al-Si-(Mg) alloys, which include 176 pieces of data from 50 publications, were established in the present work and displayed in the Supplementary Materials. Figure 1A and B shows the distribution of UTS, YS, and EL for different SLMed Al-Si-(Mg) alloys, mainly including Al4Si [3,4] , Al7SiMg [12,13,24,[49][50][51][52][53][54][55][56][57][58][59][60] , AlSi10Mg [9][10][11][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] , and Al12Si [4,5,14,[40][41][42][43][44][45]…”

In Situ Ageing with the Platform Preheating of AlSi10Mg Alloy Manufactured by Laser Powder-Bed Fusion Process

“…Furthermore, their studies showed a decrease in hardness between the building bottom and top. Nevertheless, the manufacturing times were lower for the studies in [27,28] and were identical for the study in [29] but at lower temperatures. Thus, the preheating temperature and the number of samples on the platform play a role in the hardness evolution as a function of the distance to the manufacturing platform.…”

“…In the literature, it has been reported that exothermic peaks related to the formation of GP, β", β', and β occur around 100, 250, 300, and 500 • C [6,[35][36][37][38][39]. It has been reported that when a 150 °C preheating is chosen, the bottom and top hardness do not have the same mechanical response to a 170 °C ageing; whatever the direct ageing temperature (175, 200, or 225 °C), the hardness values from the bottom only decrease with time while hardness at the top can achieve a maximum with an ageing temperature of 175 °C [28,29]. There is then a difference in the hardening potential between the top and bottom of a fabrication.…”