Advanced Materials Research Vols. 652-654

Abstract: The use of electrostatic probe is available and simple in atmospheric TIG arc plasma diagnostic. Usually electrostatic probe takes disturbance in arc plasma due to sweeping motion. A low disturbance electrostatic probe was developed. This probe consisted of aluminum wire and moved through arc plasma along probe’s longitudinal direction to avoid sweeping motion. And the signal collected by this probe required Abel inversion to convert into the value per 1 mm probe length. With the application of the low disturbance probe in biased condition, ion saturation current density in various sections along the axial direction of TIG arc was obtained. The result shows that half width and peak value of ion saturation current density increase with the enhance of arc current; the radius of current-carrying area can be estimated by the half width of ion saturation current density; along the axial direction of TIG arc, the radius of current-carrying area change to the minimum near cathode.

Abstract: In order to predict deep drawing steel laser tailor-welded blank corrosion resistance accurately and quickly as well as adjust and optimize laser welding process parameter, the Optimal Discrimination Plane (ODP) method was employed to analysis the mapping relation between laser tailor-welded blank corrosion resistance and laser power, welding speed, spot diameter, focal length, absorptivity, laser tailor-welded blank Partial Least Square (PLS) corrosion resistance prediction model was built based on the major factors orthogonal test. The experimental results show that the laser tailor-welded blank prediction accuracy of this model is above 96%, which shows that the model has good experiment/prediction agreement and proves that this model is valid and practical.

Abstract: Distribution of magnetic flux density and magnetic force in electromagnetic riveting was investigated with the electromagnetic field coupling model established by the finite element method. The results show the radial magnetic flux density presents a sinusoidal exponential decaying form at a point and the maximum value of radial magnetic flux density lies in about half of the driver plate radius along the driver plate radius direction. The distribution of magnetic force is determined by that of magnetic flux density and the magnetic force is a body force, which weakens very quickly from the inside to the outside of the driver plate. In order to prevent penetration of magnetic field, the thickness of driver plate is an important parameter to increase the energy utilization ratio.

Abstract: In this work, the Gurson-Tvergaard-Needleman (GTN) damage model is adopted to depict the material damage during the clinch joining process in a simulation-based theoretical model. The parameters of the GTN model which influence the void nucleation, growth and coalescence are identified. Their values of a specific material, C45E4 (ISO) steel, have been determined after carefully comparing the simulation results with the real sheet material tensile test. The established GTN damage model parameters are then imported into the simulation model to investigate the material damage during the mechanical clinch joining process. The Finite Element Analysis (FEA) simulation results show promising, because the material’s initial damage position can be located and analyzed. For a given design, the initial fracture point was predicted which is located on the inner side of the clinched joint neck of the upper sheet, which matches with the results of the experimental test very well. It can be concluded that the incorporation of GTN damage model has extend the capability of the simulation model.

Abstract: The main aim of this research study 0 degrees to the shoulder to the welding of aluminum alloy rolled grade 6063 and 7075 were made by a friction stir welding. The variables welding speed to determine the tensile strength and macro-structure of specimens. The results were summarized. Variables to make major changes to the weld is incomplete and the defects in the weld. When the welding speed is not reasonable. Shoulder is available to heat the material to make two kinds of weakness. The top surface is not smooth still the scale. On both of materials have fin. Defects in the weld is still going on in the shoulder of tool to 0 degrees to provide maximum strength is 180 MPa at 1000 rpm with a welding speed 50 mm / min

Abstract: The surface tension of the liquid metal droplet was measured in the welding arc fields using a novel method. This method eliminates the interference of the electrode magnetic force and aerodynamic drag force with the measurement results during the welding process. The validity of test method was recognized by both theories and experiments. The surface tensions of the H08A wire melting droplet were measured at various currents.

Abstract: The weld width of laser welding not only affects the tailor welded blank forming properties, but also leads to fracture failure to a great extent during the stamping process. In order to optimize the weld process and ensure laser welded tailored blanks (LWTBs) forming properties, the weld width should be predicted and controlled. Firstly, the transient temperature field distributions are simulated by means of the finite element software. Then the weld widths are calculated based on the analysis of test plate temperature distribution. Additionally, weld width prediction model is put forward by means of Partial least squares (PLS). And the forecasting relative error of weld width is below 5%. Then it can be concluded that the proposed model is reasonable and applicable.

Abstract: This paper introduced a kind of bainite steel used for frog, and studied its repair welding processes. In this paper, four different welding processes were designed. Optical microscopy, scanning electron microscopy, vicker hardness tester, wear tester, impact tester, and high temperature abrasion tester were used to test microstructures, hardness, wear weight loss, impact absorbing energy and wear morphology. The conclusion was that when the current was 120A and the preheat temperature was 250°C the hardness of surfacing metal was the highest, the wear weight loss was least and the impact absorbing energy was the highest. In practical repairing works, this process could be considered.

Abstract: Regarding dangerous defects such as cracks and lack of fusion in the joint weld of conical head and tube of grid structures and presented problems in NDT, research on usability of the defective grid structure was carried out through theoretical computations and experimental tests of mechanical properties of defective welds with specification of Φ60×3.5mm. Specific advice concerning quality control of the joint weld is given.

Abstract: The active droplet oscillation is a method previously proposed to detach the droplet at currents below the transition current. In this method, a droplet oscillation is actively excited when the current is switched from the exciting peak level to base level. The downward momentum of the droplet is utilized to enhance the droplet detachment. In this work, the current waveform is modified to achieve stronger droplet oscillation with lower average current. The critical change is to separate the droplet growing and exciting processes such that the two processes can be controlled independently. The heat input can thus be reduced, and stronger droplet oscillation is obtained. A further optimized current waveform is proposed to maximize the droplet oscillation energy despite the growing current level.