Abstract: The Selective Laser Melting (SLM) process has been proved as the most effective method among Additive Manufacturing (AM) technologies to produce hard, dense and strong metallic structures with intricate shapes and profiles from wide range of metallic alloys. The SLM generated structures from 17-4PH stainless steel high strength alloys involve layer by layer building up through laser melting of successively deposited powder layers. Therefore, the mechanical properties of such structures need to be thoroughly checked and investigated before putting these materials to practical applications. This research mainly investigates the cryogenic impact properties of SLM generated 17-4PH specimen. These characteristics are very important in applications requiring high strength customized structures that could maintain their mechanical properties at sub-zero temperatures. The experimental analysis proves that SLM is a very reliable technology to produce high strength metallic structures and these specimens can function efficiently in extreme conditions.
Abstract: Indonesia has the most laterite ore reserves in the world. The element originated from the laterite ore is one of the materials in the steel industry. Despite its plentiful of reserves, laterite steel ore has not been used to its maximum potential. This research aims to overview reduction effect on mechanical properties of laterite steel as a result of heated rolling process with various reduction. The reduction variety used in this research were 30%, 40%, 50%, and 60%. Also, the temperature was 980oC. As a result of this research, the increment of reduction followed by the increment of hardness and firmness level of laterite steel. It is proofed by hardness and tensile test. Firmness of the material increased as the reduction increases. The most optimized mechanical properties obtained by 50% reduction, the hardness number was 280.03 HB, tensile strength 620 MPa, elongation 32%, yield 493.33 MPa. Micro structures which formed in this process are ferrite and pearlite phase with very fine pellet size and even pearlite distribution. Fracture types are brittle and ductile fracture with very fine pellet size.
Abstract: The purpose of this research was to evaluate the hardenability of ASSAB 760 (equivalent to AISI 1045 and JIS S45C) steel subjected to the gas cementation, the quenching and the tempering processes. Gas cementation is a heat treatment surface process by means of carbon diffusing into steel. This process is carried out in a furnace in a fluidized bed by using media of liquid petroleum gas (LPG) and nitrogen gas at a temperature of 1203 K and various holding times of 7.2, 10.8 and 14.4 ks, respectively. The rapid quenching process is carried out in an oil media for 420 sec. In order to remove the tension in the specimen, the tempering process is carried out in a furnace at a low temperature of 473 K with holding time of 3.6 ks. The result shows that, the Vickers hardness values can be achieved from 568 to 584 HV. Therefore, it is confirmed that by using these processes, the hardening of ASSAB 760 steel can be carried out and the punch holder can be manufactured.
Abstract: In this paper, a TA2/Q235B composite plate was bonded with a DT4 interlayer by hot-rolling in a vacuum. The resulting interfacial structure and mechanical properties were analyzed. The results show that when the reduction is 25%, the rolling speed is 50 mm/s, and the bonding temperature is between 750 and 850°C, the shear strength of the bonding interface increases with temperature. It is difficult to bond TA2 and DT4 at a bonding temperature of 700°C. Brittle compounds, i.e., TiC, FeTi and Fe2Ti, are formed at the interface when the bonding temperature is 950°C, and the bonding strength significantly decreases. When the bonding temperature is 850°C, the shear strength of the interface reaches a maximum of approximately 237.6 MPa, and the fracture surface presents ductile fracture characteristics.
Abstract: Hand-tool is one of the important products which are widely used in manufacturing industry as well as in human life. The torx is one kind of hand-tools which is considered as a case study in this research. There are two trial preforms designed to analyze their influence on forgings formability. Firstly, DEFORM-3D software was used to simulate and analyze forming processes of different preform shapes for observing the formability of each trial preform and defects during the forming processes. Die stress analysis was also conducted to investigate the die stress of the forming stages in different forming processes. Secondly, according to the formability and the die stress, the most suitable forming processes and preform were selected for actual experiments. Finally, to verify the simulation results accuracy, the feature matching and hardness test were performed. The result of this research show that appropriate forming processes and preform applied improve the quality of product compared to original product.
Abstract: The static shear extrusion bonding experiment was carried out on the Q345 plates by the solid-state metal joining device with fast shearing. Meanwhile, based on the experimental and theoretical analysis, the influence of shear rate, the press quantity on the interface formation and microstructures evolution mechanism during shear extrusion bonding process were analyzed, and mechanical properties was investigated. The results show that with the increase of the press quantity, the interface formation divides into three stages, and the grain refinement is improved through dynamic recrystallization. The deformation work is provided by the bonding device, which is affected by shear rate. When the press quantity reaches 125%, the tensile strength of the specimens with high shear rate and low rate are 499.56MPa and 500.56MPa, respectively.
Abstract: Machinability of aerospace material, Inconel 625 through Wire cut electrical discharge machining has been performed and compared using Taguchi’s Orthogonal L18 (21*35). Normal diffused and cryogenic treated diffused wires are being used as a tool electrode to investigate the effects of machining parameters viz. tool electrode, peak current, pulse on time, pulse off time, wire feed and wire tension on the response MRR. The present study resulted that cryogenic treated tool electrode give better performance in comparison to normal wire electrode assisting in improving stock removal and less electrode wear. Pulse on time and peak current are observed as the most influenced parameter. Scanning Electron Microscopy (SEM) studies has been conducted and presented.
Abstract: Ti-6Al-4V is a titanium alloy having high strength, low weight and corrosion resistant which is a required characteristic for a material to be used in aerospace industry. Titanium, being a hard alloy is difficult to the machine via conventional methods so it is a call to use non-conventional processes. In present work, the effects on Ti-6Al-4V by drilling a hole of Ø 6 mm using copper (99%) electrode in electric discharge machining (EDM) process is analyzed. Experiments were performed under different operating conditions of peak current, pulse-on time and pulse-off time. Multi-objective optimization technique Grey relational analysis is used for process optimization of material removal rate (MRR) and electrode wear rate (EWR). Experiments are designed using an L9 orthogonal array. ANOVA is used for finding most contributing parameter followed by confirmation tests for validating the results.
Abstract: The computer simulation methods of cake growth properties were studied for the slip casting of alumina with gypsum mold. Based on the two-phase flow mixture model, mass conservation of water and maximum close-packed density theory, the numerical calculations were performed for the dynamical cake uniformity, cake density, mold thickness and effective applied pressure in this work. Good agreement was observed between the experimental experience and simulated cake uniformity with the different volume fractions of the slurry and the different sprue gate location conditions. The air-dried cake density and appropriate mold thickness can be estimated quickly by the present formulas. It is useful to simulate the dynamical cake properties with different process conditions which are difficult to detect.