Optimization of Si Content to Inhibit Inhomogeneous Deformation in Al-Mg-Si Alloy Fabricated via Twin-Roll Casting

Abstract

Herein, the effects of Si content on the microstructure evolution of Al-Mg-Si alloys during twin-roll casting (TRC) and subsequent heat treatment were characterized using scanning electron microscopy, emission electron probe micro analysis, electron backscatter diffraction, and transmission electron microscopy. The effects of insoluble Si particles, solute gradient, and recrystallization on the mechanical properties of the alloy in the T4P state were analyzed. An inhomogeneous deformation in the thickness direction of the TRC strip was observed during the pre-strain test. A premature local deformation at the element barren region (EBR) in the middle of the strip was considered to be the origin of the limited mechanical properties. By increasing the Si from 0.7 wt% to 1.1 wt%, the content and uniformity of the solute in the EBR can be effectively improved. The stronger work-hardening ability weakens the inhomogeneous deformation. Si addition significantly increased the number of insoluble Si particles during the heat treatment. The structure with a hard shell and soft core in the TRC strip significantly reduced the negative effect of insoluble Si particles on the mechanical properties. The tensile strength and uniform elongation of the strip increased from 159.44 MPa and 18.36% to 209.96 MPa and 29.791%, respectively.

Planning Mechanical Behavior of A356 Alloy Wheels by Using Distinct Heat Treatments

“…and addition elements such as Ti and Sr as grain refiners, and Si for eutectic morphology modification. Moreover, the literature also discusses solution treating, quenching, and artificial aging of the microstructure and on mechanical behavior [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. These articles were probably written because Al-Si-based alloys exhibit excellent castability and affordability and have a low coefficient of thermal expansion and attractive mechanical properties, making them suitable for manufacturing wheels by casting [4][5][6].…”

“…It is widely recognized that a typical as-cast microstructural array affects the resulting properties [6][7][8][9][10][11][12][13][14][15]. When coarse Al and interdendritic Si particles are constituted, the reached ductility is considerably decreased [6][7][8][9][10][11][15][16][17][18][19][20][21][22][23]. This is associated with a plate-like eutectic Si morphology formation [6][7][8].…”

“…It provides a finer microstructural array, leading to improved fatigue characteristics, and a significant reduction in the resulting shrinkage. It is also reported that LPDC decreases the required lead time for wheel production [11,[17][18][19]. T6 heat treatment improves A356 mechanical behavior mainly in terms of ductility and elongation [11,19].…”

“…In the field of material science and engineering, extensive literature addresses Al-Sibased and A356 alloys, scrutinizing various manufacturing conditions, Si morphology modifiers, and different heat treatments [4,8]. The literature reported [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][29][30][31][32][33][34][35][36][37][38] has shown a great gamma of studies. When the PRISMA concept (preferred reporting items for systematic reviews and meta-analyses), stringers "Al-Si-based alloys", and "eutectic" are utilized when searching articles, more than 1400 papers are obtained.…”