Mechanical behaviour of Al-Mg-Si matrix composites reinforced with alumina and bamboo leaf ash

The mechanical behaviour of Al-Mg-Si alloy matrix composites reinforced with alumina and bamboo leaf ash (BLA) has been investigated. Alumina (Al2O3) particulates complemented with 0, 2, 3, and 4 wt% BLA were utilized to prepare 10 wt% of reinforcement in Al-Mg-Si alloy matrix using double stir casting method. Micro-hardness measurement, tensile testing, fracture toughness evaluation, optical and scanning electron microscopy were used to characterize the composites. It was observed that 4.7, 9.32, and 14.3 % reduction in tensile strength was obtained for the composites containing 2, 3, and 4 wt % BLA, respectively. Although there was still a decrease in specific strength and hardness with increase in BLA content, the reductions are less than 9 % for a 40 % reduction of alumina as obtained in the hybrid composite containing 6wt % alumina - 4 wt % BLA. The hybrid composites containing 2 and 3 wt % BLA exhibited a superior elongation in comparison to the single reinforced Al-Mg-Si/ 10 wt % alumina composite, while all hybrid composite compositions exhibited a superior fracture toughness compared to the single alumina reinforced composite

Mechanical behaviour of Al-Mg-Si matrix composites reinforced with alumina and bamboo leaf ash

The mechanical behaviour of Al-Mg-Si alloy matrix composites reinforced with alumina and bamboo leaf ash (BLA) has been investigated. Alumina (Al2O3) particulates complemented with 0, 2, 3, and 4 wt% BLA were utilized to prepare 10 wt% of reinforcement in Al-Mg-Si alloy matrix using double stir casting method. Micro-hardness measurement, tensile testing, fracture toughness evaluation, optical and scanning electron microscopy were used to characterize the composites. It was observed that 4.7, 9.32, and 14.3 % reduction in tensile strength was obtained for the composites containing 2, 3, and 4 wt % BLA, respectively. Although there was still a decrease in specific strength and hardness with increase in BLA content, the reductions are less than 9 % for a 40 % reduction of alumina as obtained in the hybrid composite containing 6wt % alumina - 4 wt % BLA. The hybrid composites containing 2 and 3 wt % BLA exhibited a superior elongation in comparison to the single reinforced Al-Mg-Si/ 10 wt % alumina composite, while all hybrid composite compositions exhibited a superior fracture toughness compared to the single alumina reinforced composite

Corrosion polarization behavior and microstructuralanalysis of AA1070 aluminium silicon carbide matrix composites in acid chloride concentrations

The effect of SiC content and NaCl concentration on the corrosion resistance of AA1070 aluminium in 2 M H2SO4 was evaluated with potentiodynamic polarization technique, open circuit potential measurement (OCP) and optical microscopy. Results showed SiC increased the corrosion susceptibility of the alloy at lower NaCl concentrations compared to results obtained at 0% NaCl which showed significant decrease in corrosion rates, with maximum inhibition efficiency of 90.84% at 20% SiC content. The corrosion rates decreased at higher NaCl concentration,with maximum inhibition efficiency of 94.12 and 77.27% at 20% SiC. Alloy samples in 2 M H2SO4/0% NaCl at 0 and 20% SiC visibly decreased in OCP value over wide variation compared to samples with varying NaCl concentration due to loss of passivity. OCP values for alloys at varying NaCl concentration decreased over a very short variation due to repassivation. Statistical data showed silicon carbide to be the only relevant variable responsible for the corrosion rate values with F-values of 8.85 corresponding to a percentage significance of 54.8%. Optical images showed the presence of corrosion pits of smaller dimension, yet deeper on the morphology of the alloy without silicon carbide compared the alloy containing it, whose corrosion pits, seems wider but very shallo

DEVELOPMENT AND PERFORMANCE EVALUATION OF A SALT BATH FURNACE

ABSTRACT This research work is centered on the design of a low costefficient salt bath furnace using locally sourced materials for the purpose of carrying out thermochemical treatments of small and minor components for improved properties in service. Working drawings were produced; and mild steel sheet was used for the construction of the furnace casing while other materials for the construction were selected based on functions and properties of the materials, cost considerations and ease of fabrication into component parts. Testing was carried out to evaluate the performance of the furnace. From the results obtained, it was observed that the salt bath furnace has fast heating rate 12.53 0 C/min and a fuel consumption rate of 2.1 litres/hr, which is comparable to rates of conventional brands of diesel fired salt bath and muffle furnaces purchased from abroad. The lower cost of design of the furnace coupled with its good heat retaining capacity, uniform heating rate, long estimated life time, safety and ease of maintenance justifies the usage

Structural characterization and mechanical properties of pearlite – Enhanced micro-alloyed ductile irons

Abstract: The structural characteristic and mechanical properties of ductile irons micro alloyed with lean additions of molybdenum, nickel, copper and chromium was investigated. This was aimed at assessing the potentials of the utilization of lean ferro alloy additions (which offers reduced processing and product costs) for enhancing pearlite phase proportion, which is required for improved mechanical performance of ductile irons. The ductile irons contained a maximum of 0.2% each of Mo, Ni, Cu, and Cr and were processed using a crucible furnace. They were characterized using optical microscopy and X-ray diffractometry while hardness and tensile testings were used to evaluate the mechanical properties. The results show that the micro alloyed samples contain new compound of alloying elements with iron and the base alloy phase (FeSi, a Fe). It was also observed that the micro alloy additions resulted in significant increase in pearlite proportion from 30.63% in the base alloy to as much as 59.38% in the composition containing Mo, Ni and Cu as micro addition. Increase in hardness within the range 1.4–36.5% was obtained, while tensile strength increase within the range 35.89–80.55% with the use of the micro alloying additions. Overall, the best combination of mechanical properties was achieved for the ductile irons composition containing chromium and copper, as well as the one containing molybdenum, nickel and chromium as micro alloy additions

Mechanical behaviour of Al-Mg-Si matrix composites reinforced with alumina and bamboo leaf ash

The mechanical behaviour of Al-Mg-Si alloy matrix composites reinforced with alumina and bamboo leaf ash (BLA) has been investigated. Alumina (Al2O3) particulates complemented with 0, 2, 3, and 4 wt% BLA were utilized to prepare 10 wt% of reinforcement in Al-Mg-Si alloy matrix using double stir casting method. Micro-hardness measurement, tensile testing, fracture toughness evaluation, optical and scanning electron microscopy were used to characterize the composites. It was observed that 4.7, 9.32, and 14.3 % reduction in tensile strength was obtained for the composites containing 2, 3, and 4 wt % BLA, respectively. Although there was still a decrease in specific strength and hardness with increase in BLA content, the reductions are less than 9 % for a 40 % reduction of alumina as obtained in the hybrid composite containing 6wt % alumina - 4 wt % BLA. The hybrid composites containing 2 and 3 wt % BLA exhibited a superior elongation in comparison to the single reinforced Al-Mg-Si/ 10 wt % alumina composite, while all hybrid composite compositions exhibited a superior fracture toughness compared to the single alumina reinforced composite

Structural characterization and mechanical properties of rotary melting furnace processed aluminium alloyed ductile irons

The microstructural characteristics and mechanical properties of rotary melting furnace processed aluminium alloyed ductile irons were investigated in this study. This was aimed at developing high performance – low material and processing cost ductile irons, suitable for the production of automobile components. Different compositions of the alloys were processed containing 1–4 wt.% aluminium. X-ray diffractometry, optical, scanning electron microscopy and mechanical properties measurements, were used to characterize the alloys. The results show that the ductile irons consists essentially, nodular and vermicular graphite-type distributed in a predominantly pearlite – ferrite matrix structures which attest to the viability of rotary furnace melt processing for ductile iron production. The nodule count were observed to increase with increase in Al wt.% but nodule sizes and degree of sphericity decreased with increase in Al wt.%. The mechanical properties of the ductile irons increased with increase in Al wt.%, except the ductility which decreased slightly with increase in Al wt.%

Influence of different cyclic intercritical heat treatment schedules on the microstructure and mechanical behaviour of a medium carbon low alloy steel

In the present research, the prospect of optimizing high strength and formability in medium carbon low alloy steel via different cyclic intercritical treatment procedures was investigated. Three intercritical treatment schedules (Route A - cyclic intercritical annealing only, Route B - cold rolling followed by cyclic intercritical annealing, and Route C - cyclic cold rolling and intercritical annealing operations) performed at 770o C were utilized in this research work. For each treatment route, a maximum of three heating cycles was used. Microstructural examination, hardness measurement and tensile properties evaluation were used as basis to assess the mechanical behaviour of the dual phase structures produced. The results show that for Route A and B, grain refinement and homogeneous distribution of ferrite and martensite was obtained for specimens subjected to two cycles of intercritical annealing. This resulted in peak strength, toughness and hardness in comparison to specimens subjected to one or three cycles of intercritical annealing. For Route C, the same properties were impoverished with increase in intercritical annealing cycles. The best combination of hardness, strength, toughness and strain to fracture was achieved with the use of an initial cold rolling and two cycles of intercritical annealing at 770o C