Browsing by Author "Knutsen, R D"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- ItemMetadata onlyDeformation and recrystallisation of powder processed commercially pure titanium(Maney Publishing, 2012) Knutsen, R D; Petersen, SThe hot deformation behaviour of powder sintered commercially pure titanium has been compared to the behaviour of equivalent wrought metal under identical test conditions. Deformation was performed by uniaxial compression under vacuum at 900°C at nominal strains of 0·2, 0·4 and 0·65. The deformed microstructures were rapidly cooled to room temperature and subsequently annealed at 870°C. Lower grain growth, higher flow stress and greater incidence of recrystallisation were observed for the sintered metal. This behaviour is mainly attributed to the higher interstitial levels in the sintered metal which results in a lowering of the effective deformation temperature.
- ItemOpen AccessMicrostructure evolution in Ti-6A1-4V alloy during hydrogen dosing at elevated temperature(2011) Matthews, L A; Knutsen, R DSynopsis: The embrittlement of the Ti-6Al-4V alloy by hydrogen dosing at elevated temperature has been investigated. Metal coupons were subjected to isothermal treatments in a partial hydrogen atmosphere in the temperature range from 650ºC–950ºC and the degree of embrittlement after treatment was determined by dropweight impact testing. Embrittlement was found to be inversely related to reaction temperature as a result of the combined effects of greater hydrogen absorption and titanium hydride precipitation at the lower isothermal temperatures.
- ItemOpen AccessMicrostructure evolution in Ti-6A1-4V alloy during hydrogen dosing at elevated temperature.(The Southern African Institute of Mining and Metallurgy, 2011) Matthews, L A; Knutsen, R DThe embrittlement of the Ti-6Al-4V alloy by hydrogen dosing at elevated temperature has been investigated. Metal coupons were subjected to isothermal treatments in a partial hydrogen atmosphere in the temperature range from 650ºC-950ºC and the degree of embrittlement after treatment was determined by dropweight impact testing. Embrittlement was found to be inversely related to reaction temperature as a result of the combined effects of greater hydrogen absorption and titanium hydride precipitation at the lower isothermal temperatures.
- ItemOpen AccessThe influence of Mn on the tensile properties of SSM-HPDC A1-Cu-Mg-Ag alloy A201(2011) Möller, H; Masuku, E P; Curle, U A; Pistorius, P C; Knutsen, R D; Govender, GSynopsis: A201 aluminium alloy is a high strength casting alloy with a nominal composition of Al-4.6Cu-0.3Mg-0.6Ag. It is strengthened by the Ω(Al2Cu) phase and the θ’(Al2Cu) phase during heat treatment. Further strengthening of this alloy system can be obtained through the addition of transition elements, but care must be taken as other elements might have adverse effects on the mechanical properties. The objective of this study is to determine the influence of Mn on the tensile properties of rheo-processed Al-Cu-Mg-Ag alloy A201. ThermoCalc software was used to predict the different phases that can be expected in the alloys, and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) was used to investigate the actual phases that formed. The influence of these phases on tensile properties is quantified. SEM and ThermoCalc revealed that there is an increased amount of the Al20Cu2Mn3 with increasing Mn. The tensile properties showed that high amounts of Mn do have adverse effects on the tensile properties of alloy A201, especially the ductility.