Characterization of additively manufactured AlSi10Mg cubes with different porosities
By C. Taute, H. Möller, A. du Plessis, M. Tshibalanganda, and M. Leary
Additive manufacturing can be used to produce components with complex and custom geometries. However, defects such as porosity and surface roughness can severely limit industrial applications. In this paper we report on the characterization of porosity, by X-ray tomography, in samples of AlSi10Mg produced by laser powder-bed fusion, with porosity differences induced by changes in the process parameters. A better understanding of the defects can lead to improved design and manufacturing of additively manufactured parts.
The crack growth resistance behaviour of aluminium alloy 2024-T3 at slow strain rates after exposure to standard corrosive environments
By C.C. Pretorius, R.J. Mostert, and S. Ramjee
The study investigates the effect of prior corrosive exposure on the crack growth resistance behaviour of thin sheet (3 mm thick) aluminium alloy 2024-T3 at slow strain rates. Compact tension specimens were exposed to standard corrosive environments that simulate accelerated atmospheric corrosion attack. It is postulated that the observed degradation of the Kc_e values of the exfoliation corrosion (EXCO)-exposed material is due to hydrogen embrittlement. The specimens exposed to sodium chloride underwent a similar degradation. It is unclear what were the relative contributions of the notch effects and hydrogen embrittlement to the degradation of the KR performance.
The use of 4-methylbenzenesulfonate ionic liquid derivatives as environmentally friendly corrosion inhibitors for mild steel in hydrochloric acid
By T. Nesane, S.S. Mnyakeni-Moleele, and L.C. Murulana
Two synthesized ionic liquids were evaluated for their inhibiting effect on the corrosion of mild steel in acidic solution. Organic moieties were investigated using Fourier transform infrared spectroscopy (FTIR). Gravimetric analysis showed an increase in the inhibition efficiency as the concentration of inhibitor was increased. Polarization curves revealed that the ionic liquids act as mixed-type corrosion inhibitors.
Deformation and fracture behaviour of the g-TiAl based intermetallic alloys
By M.N. Mathabathe, A.S. Bolokang, G. Govender, C.W. Siyasiya, and R.J. Mostert
Samples of b-solidifying g-TiAl intermetallic alloys of different nominal composition were produced. Microstructural examination indicated that the alloys were comprised of lamellar structures (a2+g) embedded in columnar dendritic cores in the as-cast condition. The samples showed no obvious ductility during tensile deformation, indicating the brittleness of the alloys. The fracture mode results revealed that the alloys failed by translamellar fracture with correspondingly few cleavage facets.
Evaluation of spheroidized tungsten carbide powder produced by induction plasma melting
By R.M. Dire, H. Bissett, D. Delport, and K. Premlall
Spheroidization is a heat treatment modification process that is used to convert irregular particles to spheroidal shapes. Tungsten carbide (WC) was spheroidized using anv inductively coupled radio frequency plasma at various plate powers between 9 and 15 kW. The influence of additional H2 in the sheath gas on the chemical composition of the WC was also investigated. Optical analysis of SEM micrographs indicated that the spheroidization ratio increased with increasing plasma energy.
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