Staff

Abstract:
Uniaxial testing methods to characterize materials provide only limited data that is insufficient to fully understand all aspects of their behaviour, such as initial texture or anisotropy. Therefore, this research aims to conduct complex stress loading experiments to understand the physical mechanism accountable for plastic deformation caused by monotonic tension and tension assisted by proportional cyclic torsion in the CP-Ti (Commercially Pure Titanium). The yield surface approach was applied to assess the variation of mechanical properties in the as-received and predeformed material. It was found, that such monotonic tension associated with cyclic torsion caused a significant decrease of the tensile stress. The initial yield surface obtained for the asreceived material exhibits anisotropic behaviour, whereas, the sizes of subsequent yield surface reflecting pre-deformation were reduced in all directions with exception of the tension direction.

Keywords:
yield surface,pre-deformation,plastic anisotropy,cycle loading,tubular specimen

Abstract:
Al-Cr alloys are usually used in home appliances, automotive, marine and aerospace applications as these possess superior properties like high strength-to-weight ratio, good corrosion resistance and workability. In Al-Cr alloys, chromium has severely limited strengthening effects due to its relatively low solid solubility in the aluminium matrix. The high content of chromium in Al matrix leads to the discontinuous precipitation with coarse Al7Cr intermetallic phase. In this study, powder metallurgy (P/M) technique followed by microwave assisted sintering was adopted for the synthesis of Al-xCr (x = 0, 2.5 and 5 wt%) alloys to enhance the solid solubility of Cr. Specimens were sintered at 560 ºC for one hour and cooled inside the microwave atmosphere. Sintered specimens were hot extruded and characterized in terms of the mechanical properties. Mechanical characterization showed that the addition of Cr as alloying element leads to an increase in microhardness, 0.2% tensile yield strength (TYS) and ultimate tensile strength (UTS) of the Al-alloy. However, the ductility of the Al-alloys was significantly decreased by the incorporation of Cr particulates in the aluminium matrix.

Keywords:
Al-Cr system, powder metallurgy technique, hybrid microwave sintering, mechanical properties

Keywords:
yield surface, pre-deformation, plastic anisotropy, cycle loading

Keywords:
medical fixation devices, orthopedicimplants, SEM, fracture analysis, titanium alloy, stainless steel