This project is to study the effect of welding preheat on metallurgical analysis and microstructural development. Variables such as current, speed of welding and size of specimen were fixed. In the present work, a mild steel plate with thickness of 100 mm and width size of 20 mm was used. SMAW (Shielded Metal Arc Welding) technique was chosen as it is the easiest way to perform and widely used in oil & gas and marine industries. Three different preheat temperatures were performed during the study; ambient temperature (no preheat), between 60 °C to 70°C and greater than 200 °C. The study emphasizes on the minimum preheat temperature that produce good quality welding by taking into account some of metallurgical aspects; microstructure and macrostructure development, hardness distribution at important areas in weld (Heat Affected Zone, parent metal and weld area) through thickness. From this study, code American Welding Society (AWS) D1.1 was used as a reference and it stated that for plate that has 100 mm thickness the preheat temperature should be in the range of 60 °C and 70°C. The result of microstructure and macrostructure showed that the depth of penetration was not vary too much. Hardness measurement, macro and microstructure observation were performed in order to obtain a good correlation exist between these parameters studied.

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Aluminium foam is a material that structured by porous medium with certain characteristics such as good energy absorption, high heat conductivity and good heat transfer. These characteristics that aluminium metal foam provides, can be used in wide range of applications such as on heat exchanger, automotive and etc. The aim of this study is to evaluate the heat conductivity and permeability of the aluminium foam. The porosity of aluminium foam produced by NaCl replication are ranging from 60% to 75%. Besides, simulation by CFD software were carried out to compare with the effect of pore structure on heat conductivity and to determine the heat flux. At the end of the study, the heat conductivity value and permeability of experimental and analysis were identified. The value of heat conductivity k of aluminium foam is better compared to solid aluminium when the temperature increased. The permeability of the aluminium foam is dependent on the porosity of the aluminium foam. Higher porosity resulting to a higher rate of permeability.

This study represents the injection moulding parameters optimization via Taguchi method on density and porosity of the green part of cemented carbide WC-TaC-6Co. The experiment commences with the preparation of WC-TaC-6Co feedstock mixed with 60 % palm stearin (PS), and 40 % of low-density polyethylene (LDPE). The important parameters for this study are the percentage of grain growth inhibitor (GGI), temperature of injection, injection pressure and injection speed. Utilizing orthogonal array L9 (34), signal to noise ratio (S/N) was used to determine the significant levels and its contribution to the responses of density and porosity. The study signified that for density and porosity response, injection pressure and GGI is the most influential parameters. Based on that, it was found that the best parameter combinations for density and porosity is, GGI at 1.2 wt. %, temperature of injection at 155°C, injection pressure at 55% and 50%, and injection speed at 40% and 30%. Thus, it is determined that by controlling the setting of the best parameter, the optimal quality of the desired product can be accomplished and sustained without much complications during the process.

The occurrence of wear in austenitic stainless steel is inevitably unavoidable due to the presence of high chromium content and other alloying elements that hinder the implementation of surface treatment process. This process is usually use to improve the hardness and wear properties of steels and alloys by diffusing hard protected layer on the surface of the material. This paper investigates the effect of surface attrition on the hardness and wear properties of paste boronized 304 stainless steel. Surface attrition treatment was applied onto the surface of 304 stainless steel before paste boronizing was conducted at temperature of 850°C for 8 hours holding times. The microstructure of the boronized samples before and after surface attrition treatment was then observed and recorded in order to compare the phase constituent and boride layer thickness. The hardness of each phases was then evaluated using Vickers microhardness test and the wear resistance test of both paste boronized sample and surface attrited samples after boronizing was performed using pin on disk test. The microstructure results show that there are presences of both FeB and Fe2B phases on the surface of Pa-B850 and Pa-SB with boride layer thickness improvement of 3 times compared to untreated samples. This lead to enhancement of both hardness and wear resistance of the paste boronized samples due to better protection on the surface of the 304 stainless steel. The improvement of wear and hardness properties of 304 stainless steel could introduce new application that could be exposed to environment containing friction and wear.