•The fatigue performance for two types RAFM steel specimens of TIG welding and EB welding were also tested by SDS200 electro-hydraulic servo fatigue testing machine firstly.•Some simulations and ...experiments about fatigue of RAFM steel welding specimens have been done.•The experimental results were studied to analyze the impact of fatigue resistance for different welding forms of RAFM steel.
The Reduced Activation Martensitic/Ferritic steel (RAFM steel) is known as one of the most important materials for future fusion reactor blanket. Welding process is unavoidable during the blanket manufacturing, so it is necessary to research the welding performance of the RAFM steel. Simulations and experiments regarding fatigue behavior of the RAFM steel welding specimens have been done in this paper. The simulation of fatigue behavior of tungsten inert gas (TIG) welding and electron beam (EB) welding of the RAFM steel were carried out by using ANSYS mechanical engineering code. The fatigue behavior for two types RAFM steel specimens of TIG welding and EB welding were also tested by SDS200 electro-hydraulic servo fatigue testing machine. The fatigue performance of the weld joint both for TIG welding and EB welding was tested by applying the same gradient load. The experimental results were studied to analyze the impact of fatigue resistance for the analyzed welding technologies of RAFM steel, and the results indicate that the EB welding is stable under increasing stress. Outcomes of this study can provide some beneficial indications for the blanket design of China Fusion Engineering Testing Reactor (CFETR) in the future.
In the present study, the effect of heat treatment on microstructure and mechanical properties of gas tungsten arc (GTA) welded 15CDV6 high strength low alloy steel is discussed. Experiments were ...carried out based on Taguchi L9 orthogonal array to weld 15CDV6 plate of thickness 3.7 mm. The input parameters considered in this work were current, voltage, and welding speed. Tensile strength, microhardness, and impact strength were measured as performance characteristics. Post weld heat treatment was carried out on the weldments to study its effect on the properties of weldments and microstructures were characterized using optical microscope and the X-ray diffraction analysis revealed the presence of MO2C and VC precipitates in the weld. Post weld heat treatment of the GTA welded samples and base metal successfully produced properties required for aerospace applications.
Structural steel components tend to wear when exposed to corrosive and cyclic loading environments. These components can be repaired by welding on failure. This study studied the weld parameters and ...weld quality (porosity, depth of penetration, and coating thickness), hardness, corrosion, and wear resistance during repair welding. Mild steel samples were weld coated by varying alternating (AC) and direct (DC) currents: 40 A, 50 A, 55 A, 60 A, 65 A, and 70 A. The base material used was AISI 1045 steel, and Castolin 6825 was used as the welding electrode. The results showed that three wear mechanisms were dominant: abrasion, adhesion, and delamination. The porosity in the coated samples increased with increasing currents for both AC and DC. The welding current and current type influenced the coating thickness and penetration depth. When dipped in warm NaCl solution, the corrosion mechanism experienced by both sets of coated samples was pitting corrosion. In both cases (alternating and direct currents), the hardness values increased towards the coating surface from the substrate.
During the Keyhole Tungsten Inert Gas (K-TIG) welding process, a significant amount of information related to the weld quality can be obtained from the weld pool and the keyhole of the topside molten ...pool image, which provides a vital basis for the control of welding quality. However, the topside molten pool image has the unstable characteristic of strong arc light, which leads to difficulty in contour extraction. The existing image segmentation algorithms cannot satisfy the requirements for accuracy, timing, and robustness. Aiming at these problems, a real-time recognition method, based on improved DeepLabV3+, for identifying the molten pool more accurately and effectively was proposed in this paper. First, MobileNetV2 was selected as the feature extraction network with which to improve detection efficiency. Then, the atrous rates of atrous convolution layers were optimized to reduce the receptive field and balance the sensitivity of the model to molten pools of different scales. Finally, the convolutional block attention module (CBAM) was introduced to improve the segmentation accuracy of the model. The experimental results verified that the proposed model had a fast segmentation speed and higher segmentation accuracy, with an average intersection ratio of 89.89% and an inference speed of 103 frames per second. Furthermore, the trained model was deployed in a real-time system and achieved a real-time performance of up to 28 frames per second, thus meeting the real-time and accuracy requirements of the K-TIG molten pool monitoring system.
The influences of axial external magnetic field on the microstructure and mechanical property of the AZ31 magnesium (Mg) alloy joints were studied. The microstructure of Mg alloy joint consisted of ...the weld seam, heat affected zone and base metal zone. The average grain size of weld seam welded with magnetic field is 39 m, which is 38% smaller than that of the joint welded with absence of magnetic field. And the microhardness of weld seam increases with the help of magnetic field treatment, owing to the coarse grain refinement. With coil current of 2.0A, the maximum mechanical property of joint increases 6.7% to 255 MPa over the specimen without magnetic field treatment. Furthermore, fracture location is near heat affected area and the fracture surface is characterized with ductile fracture.
Inconel 718 is widely used super alloy for high temperature applications in aeronautical and aerospace industries. The present work is to investigate the effect of welding parameters of Inconel 718 ...alloy welds in the tungsten inert gas (TIG) welding process. Post weld heat treatment (PWHT) was also carried out at 750°C/8h/furnace cooling followed by 650°C/8h/air cooling on the weldments. The microstructural and mechanical properties were studied in base metal (BM), weld zone and heat affected zone (HAZ) with different parameters. Based on the results, the welding parameters were fixed to get the optimum properties for Inconel 718.
In the present work, Titanium grade 5 (Ti-6Al-4 V) and low carbon steel (A516) plates were joint through diffusion bonding using a titanium as interlayer at the temperatures range of 650 °C–700 °C ...for various diffusion timing of 1hr 5 min under 15KN load in vacuum to examine the strength of the welded materials at the joints. TIG welding was used to join the two different metals at three different temperature ranges. In this investigation, mechanical properties such as tensile strength, elongation, and hardness tests were carried out by using universal testing machine (UTM). Also corrosion resistance test conducted using the salt spray test to examine the corrosion resistance at the welded joints. Thus the result revealed that TIG welding is suitable for joining hard metals at maximum temperature and the welding bond strength is observed better at 700 °C.
It is necessary to estimate the weld bead width and depth of penetration using suitable sensors during welding to monitor weld quality. Among the vision sensors, infra red sensing is the natural ...choice for monitoring welding processes as welding is inherently a thermal processing method. An attempt has been made to estimate the weld bead width and depth of penetration from the infra red thermal image of the weld pool using artificial neural network models during A-TIG welding of 3 mm thick type 316 LN stainless steel plates. Real time infra red images were captured using IR camera for the entire weld length during A-TIG welding at various current values. The image features such as length and width of the hot spot, peak temperature, and other features using line scan analysis are extracted using image processing techniques corresponding to particular locations of the weld joint. These parameters along with their respective current values are used as inputs while the measured weld bead width and depth of penetration are used as output of the neural network models. Accurate ANN models predicting weld bead width (9-11-1) and depth of penetration (9-9-1) have been developed. The correlation coefficient values obtained were 0.98862 and 0.99184 between the measured and predicted values of weld bead width and depth of penetration respectively.
