Papers by Keyword: Stainless Steel 304

Abstract: Stainless steel 304 is one of the most widely used authentic stainless steel due to its high corrosion resistance. The use of cooking utensils can cause internal corrosion, where the inside of metal cookware and in direct contact with cooking ingredients will corrode and mix with food, so an organic coating is needed to increase its corrosion resistance. This study used chitosan as an organic coating with variations in chitosan concentration of 0.5; 0.4; 0.3; 0.2; and 0.1 wt%, the coating method used was electrodeposition, the voltage and coating time was kept constant at 10 volts and 10 minutes. After coating, the coated specimens will be tested for layer density, layer thickness, corrosion rate using a potentiodynamic polarization test. The results in this study obtained that the highest thickness and the lowest corrosion rate were on specimens with a variation of chitosan concentration of 0.5 wt% with a coating thickness and corrosion rate of 85.56 ± 4.67 m and a corrosion rate of 0.14403 mm/year, while the highest layer density was in specimens with a variation of chitosan concentration of 0.3 wt% with a layer density of 0.000360181gram/mm³. This is due to the viscosity of the electrolyte solution when coating, which affects the movement of electric current in the electrodeposition process.

Abstract: Dissimilar metal welding was mostly done to optimize the application and engineering requirements with economic considerations. Weld microstructures greatly influenced the mechanical properties of welded joints. The investigations were carried out to evaluate the microstructural and mechanical properties of dissimilar weldment between carbon steel ASTM A36 and austenitic stainless steel 304 with a variation of welding position (1G, 2G, 3G) and weld thickness (6 mm to 12 mm) joints by TIG welding. A detailed analysis was conducted on the weld zone composition, the microstructural, and mechanical properties. The results show that the welding position and thickness of the weld joints influenced the microstructure both in HAZ and weld metal. Size, distribution, and orientation of microstructure were improved and more uniform with increasing of welded joint thickness. In HAZ carbon steel, GB ferrite was dominant, especially for the flat welding position (1G), while for the horizontal position (2G) and the vertical welding position (3G) showed other structures such as Widmanstaten ferrite, hard-structures like martensite and bainite. In the region near the fusion line and the weld metal, the chemical composition changed due to thermal convection, diffusion, and macro-segregation caused by penetration of liquid metal carbon steel into the weld pool. SEM/EDS results indicated diffusion of carbon from carbon steel A36 to stainless steel 304 and formed the hard-structure along the fusion line. The mechanical test results showed that the tensile test breaking point occurred in the parent metal of carbon steel A36. The bending test results showed very high stress on the face side of the welding joint, and there are no cracks from the bending test result. Vickers hardness testing showed that the hardness distribution increased from the carbon steel HAZ to the stainless steel HAZ, and the maximum hardness has achieved the value of 297 Hv at the fusion line of stainless steel 304.

Abstract: This paper presents the results of research on the manufacturing of steam turbine blade by using investment casting technology. Metal forming technology with precision casting process or investment casting is the right technology for the manufacture of turbine blades, because it can produce casting products that has advantages in size and shape accuracy, surface finish and the ability to produce thin casting, which the usually foundry can not be done. The purpose of this research is to produce a good quality of the casting products as an effort to reduce import dependency of steam turbine blade and to be the alternative way of making steam turbine blades in Indonesia, in addition to the machining process. Based on the experimentation trial implemented on casting products of stainless steel 304, the result indicates that the injection temperature for the wax NF-411 and optimal nozzle in hydraulic injection machine are 64°C and 30°C, injection pressure 1.75 MPa and injection time 9 seconds. The best casting induction furnace achieved at temperature 1,620°C as for to the number of ceramic mould coat which is good to be obtained at 7 layers. The testing results show that: (1) the chemical composition is appropriate with standard, (2) the hardness is 160 HB, (3) the shrinkage is 2.83%.

Abstract: Vibration is a common phenomenon in cutting process, which is harmful for machining quality and machine tools. This paper focused on the occurrence and characteristics of vibration of the cutting tool and workpiece by changing cutting speed in milling of stainless steels 304. Vibration acceleration signals of both the cutting tool and the workpiece were sampled and analyzed in time domain and frequency domain. Vibration noise and vibration mark were used to judge the occurrence of violent vibration. In the experiments, both self-excited vibration and violent forced vibration were found at different value of cutting speed. Violent forced vibration was easy to be induced owing to interrupted continuous impulsion cutting.The Maximum amplitude of vibration acceleration signals varied with the cutting speed changing. With the cutting speed increased, the probability of violent vibration increased. Bigger amplitude of vibration will not always lead to vibration mark on surface of workpiece, obvious vibration mark only occurred when n=600 r/min and 700 r/min. In order to reduce the impact of violent vibration on machining quality, more attention should also be paid to the static and dynamics characteristics of the cutting tools and workpiece in milling of stainless steels.

Abstract: High strength, high ductility and low thermal conductivity cause the austenitic stainless steels to be hard materials to machine so that heat concentrates at the tool cutting edge due to their properties. This study aims to optimize turning parameters of AISA 304 stainless steel. Turning tests have been performed in three different feed rates (0.2, 0.3, 0.4 mm/rev) at the cutting speeds of 120, 160 and 200 m/min. An analysis of variance (ANOVA) has been made to determine the effects of each parameter on the tool wear and the surface roughness using the Taguchi approach. It is being inferred that cutting speed has the main influence on the flank wear and as it increases to 200 m/min, the flank wear decreases. The feed rate has the most important influence on the surface roughness and as it decreases, the surface roughness decreases as well.

Abstract: Nowadays, many economist and scientist worried for sharply increased to fuel consumption. Developed and developing countries investigation new energy system. It is base on the low emission gas, high energy efficiency, permanence and cogeneration. Specially, transportation system has restricted to system’s total weight. It is concern with light weight offer to increase to performance by itself. And give to other benefit that reduce to oil consumption, improved fuel economy, engine downsizing and increased to Market-value. Fuel cell is one of the new energy systems for next generation. Normally, fuel cell is consisting of bipolar plate, MEA (Membrane Electrode Assembly) and GDL (Gas Diffusion Layer). Conventional bipolar plate material was applied Graphite. Graphite has very weak for external shock, machining process is not easy, and the main problem is that the graphite material supplied by oxidizing and reducing agent composition of the gas leak comes. Thus, by this reason, the manufacturing cost is increased. In this study, to replace the graphite material was selected as a metal material. In this experiment, STS304 austenite base stainless steel is used. This study was based on the metal material’s corrosion behavior observed with 2 type’s surface pretreatment on the STS304 with similar PEMFC operating condition. Experimental results, As-Polished condition has good corrosion resistance better than As-Received condition. It was concerned with passivation layer.

Abstract: Residual stresses are an integral part of the total stress acting on any component in service. It is important to determine and/or predict the magnitude, nature and direction of the residual stress to estimate the life of important engineering parts, particularly welded components. This work aims to introduce experimental models to predict residual stresses in the heat-affected zone (HAZ). These models specify the effect of laser welding input parameters on maximum residual stress and its direction. The process input variables considered in this study are laser power (1.03 - 1.368 kW), travel speed (26.48 – 68.52 cm/min) and focal point position (- 1 to 0 mm). Laser butt-welding of 304 stainless steel plates of 3 mm thick were investigated using a 1.5 kW CW CO2 Rofin laser as a welding source. Hole-drilling method was employed to measure the magnitude, and direction of the maximum principal stress in and around the HAZ, using a CEA-06- 062UM-120 strain gauge rosette, which allows measurement of the residual stresses close to the weld bead. The experiment was designed based on Response Surface Methodology (RSM). Fifteen different welding conditions plus 5 repeat tests were carried out based on the design matrix. Maximum principal residual stresses and their directions were calculated for the twenty samples. The stepwise regression method was selected using Design-expert software to fit the experimental responses to a second order polynomial. Sequential F test and other adequacy measures were then used to check the models adequacy. The experimental results indicate that the proposed mathematical models could adequately describe the residual stress within the limits of the factors being studied. Using the models developed, the main and interaction effect of the process input variables on the two responses were determined quantitatively and presented graphically. It is observed that the travel speed and laser power are the main factors affecting the behavior of the residual stress. It is recommended to use the models to find the optimal combination of welding conditions that lead to minimum distortion.