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

NUMERICAL SIMULATION OF OUTER DIE ANGLE OF EQUAL CHANNEL ANGULAR EXTRUSION PROCESS

The study of the simulation of effect of outer die angle in Equal Channel Angular Extrusion (ECAE) process was investigated. The simulation was carried out on 6063 aluminium alloy with a view to achieve ultra-fine grain structures. ADINA user interphase Version 8.6 (900 modes) was used for the simulation. The unextruded parameters of the 6063 aluminium alloy were used as input codes and some basic assumptions were made in designing the model on 2-Dimensional scale. The billet was meshed by dividing the vertical and horizontal geometry into 30 and 4 elements respectively. The die angle was varied from 0o to 90o and the simulation results were displayed. The results showed that the force of 27.5X106 N, 27.5X106 N, 27.6X106 N and 31.2 X106 N was required to deform when the outer die angle was 0o , 22.5o , 45o and 90o respectively. Also, the strains achieved were 0.61, 0.62, 0.66 and 0.69 respectively. Thus, highest force is required at 90o and the strain achieved at 0o is the lowest. Based on the results, it was recommended that it is more economical to extrude at an outer angle between 22.5o and 45o as a relatively higher effective strain will be induced

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

NUMERICAL SIMULATION OF OUTER DIE ANGLE OF EQUAL CHANNEL ANGULAR EXTRUSION PROCESS

The study of the simulation of effect of outer die angle in Equal Channel Angular Extrusion (ECAE) process was investigated. The simulation was carried out on 6063 aluminium alloy with a view to achieve ultra-fine grain structures. ADINA user interphase Version 8.6 (900 modes) was used for the simulation. The unextruded parameters of the 6063 aluminium alloy were used as input codes and some basic assumptions were made in designing the model on 2-Dimensional scale. The billet was meshed by dividing the vertical and horizontal geometry into 30 and 4 elements respectively. The die angle was varied from 0o to 90o and the simulation results were displayed. The results showed that the force of 27.5X106 N, 27.5X106 N, 27.6X106 N and 31.2 X106 N was required to deform when the outer die angle was 0o, 22.5o, 45o and 90o respectively. Also, the strains achieved were 0.61, 0.62, 0.66 and 0.69 respectively. Thus, highest force is required at 90o and the strain achieved at 0o is the lowest. Based on the results, it was recommended that it is more economical to extrude at an outer angle between 22.5o and 45o as a relatively higher effective strain will be induced

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

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

The Thermal Analysis of Fuel Fired Crucible Furnace Using Autodesk Inventor Simulation Software

The reasons for failure of locally made furnace in the foundries were as a result of cycles of operating temperatures that they were subjected to, which caused thermal stress and strain on the furnaces. This paper studied the simulation of thermal analysis of Fuel fired Crucible Furnace to predict the effect of thermal stress and strain on it

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

Study of the Performances of Nano-Case Treatment Cutting Tools on Carbon Steel Work Material during Turning Operation

The degree of holding temperature and time play a major role in nano-case treatment of cutting tools which immensely contributed to its performance during machining operation. The objective of this research work is to carryout comparative study of performance of nano-case treatment tools developed using low and medium carbon steel as work piece. Turning operation was carried out under two different categories with specific work piece on universal lathe machine using HSS cutting tools 100 mm x 12mm x 12mm that has been nano-case treated under varying conditions of temperatures and timeof 800,850, 900, 950oC and 60, 90, 120 mins respectively. The turning parameters used in evaluating this experiment were cutting speed of 270, 380 and 560mm/min, feed rate of 0.15, 0.20 and 0.25 mm/min, depth of cut of 2mm, work piece diameter of 25mm and rake angle of 7o each at three levels. The results of comparative study of their performances revealed that the timespent in the machining of low carbon steel material at a minimum temperature and time of800°C, 60 mins were1.50, 2.17 mins while at maximum temperature and time of 950°C , 120 mins were 1.19, 2.02 mins. It was also observed that at a corresponding constant speed of 270,380 and 560mm/min at higher temperature and time, a relative increased in the length of cut were observed. Critical observation of the result showed that at higher case hardening temperature and time (950°C/120mins), the HSS cutting tool gave a better performance as lesser time was consumed during the turning operation