Mechanical Behaviour and Microstructural Characterization of Carbon Steel Samples from Three Selected Steel Rolling Plants

The research investigated the mechanical behavior of samples of steel rods obtained from three selected Steel Rolling Companies in South Western part of Nigeria. This was done by carrying out some mechanical tests such as tensile, impact and hardness as well as microstructural examination.Four sets of 16 mm steel rod samples were collected from Tiger steel industries, Phoenix steel and Oxil steel Industies, all located in South West Nigeria, The chemical composition was carried out using a Spectrometer (EDX3600B). Afterwards, different samples were prepared, cut and machined according to ASTM standards dimensions of tensile and impact tests as well as hardness test from which their Ultimate tensile Strength, Yield strength, Percentage elongation, Impact strength and Brinell hardness number were obtained and compared to three standards (ASTM A706, BS 4449 and Nst 65-Mn). Their microstructures were also examined and analyzed.The results showed that the Ultimate tensile strength for the samples from Oxil steel, Phoenix Steel and Tiger steel were 661 N/(mm)2, 653 N/(mm)2 and 631 N/(mm)2 respectively while their hardness values were 150 BHN, 178 BHN, 214 BHN respectively. The sample from Tiger steel and Oxil Steel had the finest and most coarse microstructure respectively. In conclusion, it was observed that the results of the sample analysis from the three selected Steel Rolling Companies conformed to most of the standards except the sample from Tiger steel which had a high hardness value compared to the standard

Material Selection for Fuel Fired Crucible Furnace Using GRANTA

The study investigated the material selection for the fuel fired crucible furnace using bubble charts. The results were generated using GRANTA software. Different properties were considered during the selection of the materials for the furnace. The appropriate engineering materials were sought locally for the design and construction of the fuel fired crucible furnace. Among several parameters taken into consideration are strength/weight ratio, formability, cost and ability to fulfill specific service functions. All these were taken into consideration during the material selection process for the fuel-fired crucible furnace. These properties were plotted against each other in bubble chart and the selection of the appropriate candidate material was done on the bubble chart. The software plotted the properties of each unit of the furnace in form of bubbles and the candidate material where selected from the bulk of materials suggested by the software. The functions, objectives and constraints of the parts or the units to be designed were adequately specified and the material properties to be selected were determined based on these fundamental parameters

Modeling heat flow across fuel-fired crucible furnace using ADINA

-The study simulated the heat flow across a fuel-fired crucible furnace using ADINA Software. Appropriate engineering materials were selected for the design and construction of the fuel fired crucible furnace. Among several parameters taken into consideration were strength/weight ratio, formability, cost and ability to fulfill specific service functions. Heat dissipation to the outside was minimal and this was clearly shown in the temperature gradient. Heat dissipation was uniform within the flame gap and inside the crucible pot. The Kaolin refractory material used showed very good insulation capacity significantly reduced heat losses. The modeled temperature distribution profile, heat flux and the temperature gradient were all in agreement with the validated results

Equal Channel Angular Extrusion Characteristics on Mechanical Behavior of Aluminum Alloy

Materials strengthened by conventional methods such as strain hardening, solute additions, precipitation and grain size refinement are often adopted in industrial processes. But there is limitation to the amount of deformation that these conventional methods can impact to a material. This study focused on the review of major mechanical properties of aluminum alloys in the presence of an ultrafine grain size into polycrystalline materials by subjecting the metal to an intense plastic straining through simple shear without any corresponding change in the cross-sectional dimensions of the sample. The effect of the heavy strain rate on the microstructure of aluminum alloys was in refinement of the coarse grains into ultrafine grain size by introducing a high density of dislocations and subsequently re-arranging the dislocations to form an array of grain boundaries. Hence, this investigation is aimed at gathering contributions on the influence of equal channel angular extrusion toward improving the mechanical properties of the aluminum alloys through intense plastic strain

Maintenance of the Federal Secretariat Complex Minna, Niger State: A Post Occupancy Evaluation Approach

Government office buildings in Nigeria are generally faced with premature but steady and rapid deterioration, decay and dilapidation due to lack of maintenance. This study evaluates the main factors responsible for the poor maintenance of the Federal Secretariat Office Complex, Minna, Nigeria using a post-occupancy evaluation approach. The study determines the extent of dilapidation of the office building and the feelings of the users about their office environment. The most frequently recurring maintenance problems are ascertained. By using occupants as a benchmark in evaluation, this paper discusses research with the broad aim of developing a general guideline for the POE practice, specifically for government and public buildings in Nigeria. The research method used was a combination of the descriptive and analytical survey methods. A total of 20 structured questionnaires comprising were administered to the users of the office building. The data collected were analyzed using descriptive and inferential statistics. Some of the findings of the study are that the major contributors to the maintenance problems in government office buildings in Nigeria are natural deterioration due to age, environmental effects and misuse by occupants.  Funding for maintenance was found to be grossly inadequate. The most frequently recurring maintenance problems in the office buildings are plumbing and roof leakages. Post-occupancy evaluation (POE) of buildings is vitally needed to ensure that building performance of government and public buildings and facilities is sustained. The study recommends POE as an effective, relevant and beneficial tool to be used by the public sector in evaluating the performance of government and public buildings in Nigeria. Keywords: Government Office Building, Post Occupancy Evaluation, Maintenance

Effect of Viscous Dissipation on Natural Convection Flow in a Vertical Parallel-Plate Microchannel with Suction and Injection

This paper investigates the effects of viscous dissipation on the hydrodynamic and thermal behaviour of a fully developed natural convection flow in a vertical parallel–plate microchannel with suction and injection by the Homotopy perturbation method. The velocity slip and temperature jump conditions at the walls are taken into account. The influence of viscous dissipation () on the microchannel hydrodynamic and thermal behaviour was discussed with the aid of graphs. The study reveals that the presence () and variation of viscous dissipation parameter in natural convention flow significantly affects the microfluidic system of infinite length and should not be neglected. Keywords: Natural convection, viscous dissipation, suction and injection

Microstructural Characterization and Some Mechanical Behaviour of Low Manganese Austempered Ferritic Ductile Iron

This work studied the microstructural characterization and mechanical behavior of low manganese Austempered Ductile Iron (ADI), with a view to improve the properties of iron and to increase the areas of applications. Three sets of ductile iron of specified composition were machined from Y-blocks to tensile and hardness pieces. The samples were preheated at 350 0C for 1hr and austenitised at 900 0C for 1hr in salt bath furnace. The three sets of samples were immediately austempered in the austempering salt bath furnace at uniform austempering temperatures of 300 0C, 350 0C and 400 0C for 90, 120 and 150 minutes; each sample for each temperature window. All sets were prepared for metallographic examination; tensile and hardness tests were carried out. The results showed that maximum hardness, tensile and yield strength were obtained at austempering temperature of 350 0C and at 150 minutes. At 300 0C and 350 0C, it was noticed that the hardness and strength increase with austempering time. The optimum tensile strength was 1300 MPa at 350 0C after austempering for 150 minutes. In conclusion the austempering operation has a significant effect on the mechanical and microstructural properties of ADI

Pre-and-post-operative aversion among men whose partners had caesarean delivery in a patriarchal setting.

Objectives: The study evaluated pre and post-operative perception and aversion to caesarean delivery (CD) among men whose partners underwent the procedure.Design: A multicentre cross-sectional study.Setting: Two tertiary and two secondary health facilities.Participants: Men whose partners underwent CD at the study sites.Methods: Participants were recruited by purposive sampling, data collection was through interaction via an interviewer-administered questionnaire first immediately the decision for CD was made and thereafter on the third postoperative day. Men whose partners had vaginal delivery were excluded from the study and data management was with SPSS version 21.0 while p<0.05 was significant.Results: Awareness about CD was 84.0% mainly through the healthcare workers (42.1%) and the female partner (34.1%); 88.0% of participants recommended CD for medically-indicated reasons. The greatest influence on consent was the male partner (48.8%). The major pre-operative concerns were limitation of family size (34.7%) and fear of repeat CD (34.0%). Pre-operative perceptions of CD included being expensive (60.7%), fear of the procedure (48.0%), fear of complications (45.3%) and longer hospital stay (44.0%). Aversion to CD was 30.0% pre and 5.3% post-operation; predictors of aversion were history of previous surgery among male or female partner and awareness about CD. However, there were reductions in negative perception and aversion post-operation.Conclusion: The high negative perception and aversion to CD among male partners were reduced post-operation. Healthcare workers should address the concerns and negative perceptions about CD and prioritize patient-friendly experiences during surgical operations

MECHANICAL AND MICROSTRUCTURAL CHARACTERIZATION OF DUCTILE IRON PRODUCED FROM FUEL - FIRED ROTARY FURNACE

The work compared the mechanical and microstructural properties of ductile iron produced in a locally manufactured fuel- fired rotary furnace with ASTM A 536 65-45-12, with a view to standardizing the produced ductile iron. Sets of low alloyed ductile iron were produced in form of keel Y-block inside green sand mould, using a rotary furnace of 100 kg capacity. The base alloy was treated with 5.5 wt. % Mg-Fe-Si alloy for spheroidisation followed by post inoculation with 75 wt. % Fe-Si. The samples of the as-cast were machined to mechanical test samples of tensile, yield and hardness. The microstructural and mechanical characterizations of the samples were carried out using computerized Instron Electromechanical Testing Machine (Model 3369), Mansato Tensometer (Model W) and Nikon Eclipse metallurgical microscope, Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) method. The results showed that the yield and tensile strength of the produced ductile iron were 367 and 540 MPa respectively with the hardness value of 185 BHN. The results obtained were compared with standard ASTM A 536 65-45-12 to confirm the suitability of the manufactured fuel-fired rotary furnace for the production of ductile iron