Papers by Keyword: Preheating

Abstract: Welding process is widely used as a metal assembly technique in various industries, including construction, automotive manufacturing, pressurization, and shipbuilding. In ship repair and fabrication, dissimilar welding between carbon steel and cast iron is often required, for example, in assembling appendages such as propeller shafts, yokes, and other equipment. Although cast iron offers high strength about 700 MPa and weight reduction benefits, its poor weldability due to high carbon content often leads to cracking when joined to carbon steel. Previous studies have found that preheating before welding mitigates rapid cooling and martensite formation, while buttering with Ni-based filler reduces carbon diffusion and carbide precipitation at the fusion boundary. This research has been carried out to investigate various procedures for dissimilar welding ductile cast iron A536 and carbon steel A36, as follows: (1) no preheat or buttering (Control), (2) preheating only (PH), (3) buttering only (BT), and (4) combined preheat and buttering (PHBT) to evaluate their effects on tensile strength, hardness, and microstructural evolution. Successful study of dissimilar welding between carbon steel and cast iron will reduce the cost of ship maintenance, increase its service life, and provide a path for more sustainable development.

Abstract: This article investigates the automatic welding of Ø4.5 mm high carbon steel wire frame. Using spring steel wire frame in car seat fabrication reduces its weight and helps to maintain rigidity. The thermal effect during the welding process can unacceptably deteriorate the mechanical properties of the material. It is proposed to use preheating and heat treatment to obtain a joint with required mechanical properties. To reduce of effect on entire product rigidity the thermal treatment was carried out locally in the zone of joining. Heating was carried out using a gas flame. Metallographic and microhardness measurements were used for the structural study. Mechanical properties were evaluated by static tension and free bending test. The recording of thermal cycles during the welding and heat treatment was carried out using chromel-alumel and tungsten-rhenium thermocouples.

Abstract: A two-level factorial design of experiments (DOE) approach is used to study the effect of four factors (average rubbing velocity, weld pressure, burn-off distance, and preheat temperature) on two response variables (weld strength and energy input) for the induction heating and linear friction welding of AISI 1020 steel. Weld strength, as analyzed though three-point bending, was insensitive to all four of the design factors. Pressure, upset, and velocity show statistically significant inverse, linear, and linear relationships with energy used, respectively. Pressure has the largest effect on energy used, followed by velocity and upset.

Abstract: Many researchers have studied the effects of heat treating processes on mechanical properties, corrosion and wear resistance of various martensitic stainless steels. It is crucial to comprehensively understand the role of heat treating processes on the mechanical properties of the steels with a systematic approach. In this work, the specimens were heat treated by preheating in two steps before continuing the heating to the quench temperature. The first preheating was performed in the furnace maintained at 400 °C for 5 min. The second step was done in the furnace kept at 800 °C for 5 min. Then the specimens were heated directly to the hardening temperature, 1030 °C. The specimens reached 1030 °C for a sufficient time of 30 min to form austenite and to allow enough of the carbides to be dissolved to ensure the desired combination of hardness and toughness. After hardening time was over, the specimens were quenched in water to form martensite for 2-8 s and holding in the air for 4 s, followed with water quenching for 2-8 s and cooling to room temperature. Data was collected in order to perform one-way analysis of variance (ANOVA). In this study, the ANOVA consisted of four levels of soaking time of 2, 4, 6 and 8 s and holding time of 4 s. All heat-treated specimens were then used to perform hardness and Charpy-V-Notch impact tests. The results showed that the hardness values increased with increasing of soaking time. The impact energy value slightly decreased with the soaking time range of 2-4 s whereas it rapidly decreased with the soaking time range of 4-6 s and slightly increased with the range of 6-8 s. However, the results from ANOVA showed that the soaking time did not significantly affect the averages hardness and impact energy at the level of significance of 0.05.

Abstract: For the assurance of the welding quality is very important to choose an adequate welding process. In case of this procedure specification we have to take account of the chemical composition, plate thickness of the work pieces and the used welding process with its parameters. In case of quenched and tempered steel even that limited alloys content we have to calculate the carbon equivalent and the preheating temperature. The preheating temperature depends on the carbon equivalent, the plate thickness and the welding process too. To obtains correct process parameters, important to choose and use the appropriate model [1]. For calculate the suitable preheating temperature we used the BWRA and the Séférian model too. We compared the results and made welding tests to monitoring the effect of the different preheating temperature. We used two different steel in our welding experiments, it was a carbon steel (S235JR) and a low alloyed hardening steel (28Mn6). After the welding test we measured the hardness changing in the heat affected zone (HAZ). On the base of our test results we concluded that in case of the used steels the suitable method is the Séférian’s.

Abstract: In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.

Abstract: Numerous research works are carried out to find out the additional information on effective use of vegetable oil in CI engine as a potential alternative fuel. The present work was intended to observe the outcome of preheating the transesterified oil earlier to fuel injection system thus making its properties similar to diesel. In this research mustard oil methyl ester was preheated to 90°c (MME90) and used in compression ignition engine and compared with mustard oil methyl ester (MME) fuelled at ambient temperature and diesel. The impacts of fuel preheating on engine emission with mustard oil were analyzed. Experiments were conducted with MME90 (Mustard oil methyl ester preheated to 90° C) and MME (Mustard oil methyl ester) and compared with diesel. Result confirmed increase in NOx emission for both MME90 and MME comparing diesel. Emissions such as CO, HC and Smoke were found in declining fashion for MME90 comparing MME and petroleum diesel. Preheating the mustard oil methyl ester during the fuel injection can be an exceptional way for using it in CI engines.

Abstract: Many studies have confirmed that the use of transesterifed vegetable oil as a fuel in diesel engine has resulted in lesser efficiency and inferior combustion rate when compared with petroleum diesel. Of late research works are being carried out to discover the surplus information on effective utilization of vegetable oil in CI engine as a promising alternative fuel. The present work was aimed to investigate the effect of preheating the transesterified oil just before entering fuel injection system thereby making its physical and chemical properties much closer to diesel fuel. In the present work neat mustard oil methyl ester was preheated to 90°c (MO90) and used in single cylinder, four stroke, naturally aspirated, direct injection compression ignition engine and compared with un heated mustard oil methyl ester (MO) at ambient temperature and petroleum diesel. The effects of fuel preheating on engine performance with mustard oil were clarified. Experiments were conducted with MO90 (Mustard oil methyl ester preheated to 90° C) and MO (Mustard oil methyl ester) and are compared with conventional diesel. The experimental analysis revealed that the BTE (brake thermal efficiency) of an engine was lower and BSFC (brake specific fuel consumption) was higher with unheated mustard oil methyl ester as compared to diesel fuel. However, increase in BTE and reduction in BSFC was observed with increase fuel inlet temperature of methyl ester to 90°C. Thus by preheating the mustard oil methyl ester during the fuel injection can be a good alternate fuel for CI engines in near future.

Abstract: An attempt is made to reduce the process forces and tool wear during friction stir welding of 409M ferritic stainless steel and to enhance the mechanical properties by induction preheating of base metal with different preheating temperatures at the leading of tool. It is observed that the preheating significantly decreased the longitudinal and axial forces. Tool degradation analysis was carried out to find out the loss of tool profile and material. Mechanical properties especially impact toughness values were increased due to significant reduction in the tool wear.

Abstract: This paper investigates the parameter optimization of a preheating method on stainless steel SUS304 prior to aluminium-stainless steel dissimilar welding. The welding method used was metal inert gas (MIG) with butt joint type weld. The Taguchi L9 orthogonal array was used to investigate the optimum parameter, while the mechanical strength was investigated using tensile test. Optimum levels of the process parameters were analyzed using the Taguchi parametric design approach. Parameter analysis of the tensile test results indicate that the preheated specimen with 90 °C have the maximum ultimate tensile strength of 111.27 MPa. This value is in close proximity to the calculated value of 109.02 MPa with 2% error. Through analysis of variance (ANOVA), the welding current was the dominant contributing factor with 40%. It can be concluded that the highest tensile value (111.27 MPa) for AA6061-SS304 dissimilar welding was obtained using 90 °C preheating, voltage of 17.5 V and current of 110 A of current.