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Electric resistive welding
Published in Andrew Livesey, Alan Robinson, The Repair of Vehicle Bodies, 2018
In butt welding the metals to be welded are brought into contact under pressure, an electric current is passed through them, and the edges are softened and fused together. This process differs from flash welding in that constant pressure is applied during the heating process, which eliminates flashing. The heat generated at the point of contact results entirely from resistance. Although the operation and control of the butt welding process is almost identical to flash welding, the basic difference is that it uses less current, has a constant pressure and allows more time for the weld to be completed.
Joining of Metals
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
Butt welding belongs to the resistance welding group, which also consists of the spot, seam, projection, percussion, and flash welding processes. All of these operate on the same principle, which involves heating the workpieces as a result of being a part of a high-amperage electric circuit and then applying external pressure to accomplish strong bonding. Consequently, all the resistance welding processes belong to the larger, more general group of pressure welding; without the application of external pressure, the weld joint cannot be produced.
Bridge Management Objectives and Methodologies
Published in J.E. Harding, G.E.R. Parke, M.J. Ryall, Bridge Management 3, 2014
This process is similar in principle to Rotary except that the angular rotation of the two parts is the same but the axes are slightly offset giving an orbital oscillation. It would be suitable for butt welding sections of more complex shape such as open or hollow structural sections.
A Study on Adopting Λ-Shape Groove for Laser-Arc Hybrid Welding to Construct Thick Plate Butt Welded Joints
Published in Welding International, 2020
Issei Uchino, Takamori Uemura, Koji Gotoh
DCEN (DC Electrode Negative) type CO2 gas arc welding [14–16], using REM-added wire, was used as an arc heat source for I-shaped groove butt welding. The reason for this was that a suitable back bead appearance was achieved by setting a higher voltage in the welding condition [11]. On the other hand, the previous study [16] on the superiority of DCEN carbon dioxide arc welding with REM-added wire in hybrid welding reported that a large amount of spatter is generated and a poor front bead appearance is formed when normal welding materials are treated with high voltage. Therefore, with a simple I-shaped groove, the welding conditions become more severe as the plate thickness increases, and it is therefore considered difficult to realize long joints of thick plates, which is the main objective of this research.
Study on prevention method of hot cracking under butt welding
Published in Welding International, 2022
Shintaro Maeda, Masakazu Shibahara, Kazuki Ikushima, Tsuyoshi Miwa, Kei Yamazaki, Kensaku Nishihara, Hiroyuki Takeda, Ninshu Ma
In this study, the FEM hot cracking analysis method considering mechanical and metallurgical factors was applied to butt welding to prevent hot cracking, and the effect of electrode distance on the occurrence of hot cracking during tandem butt welding was investigated. The following findings were obtained by comparing the analytical and experimental results.A comparison of the solidification growth direction determined using the BTR temperature gradient vector with the cross-sectional macro-photographs obtained experimentally confirms the good agreement between the experimental and analytical results. This indicates that crystal growth can be predicted by using the BTR temperature gradient vector even during tandem welding, although in a simplified manner.Weld hot cracking was observed at locations with large plastic strain increment in BTR in the longitudinal cross sections obtained from the analysis. This suggests that this method can be used to estimate the regions where weld hot cracking is likely to occur. It was also confirmed that the weld hot cracking occurred in the transverse section where the associate angle was close to 180°, i.e. the columnar crystals have collided on-head each other, and a large plastic strain increment in BTR was generated.When the LTorch distance between the electrodes is small, the columnar crystal associate angle becomes close to 180° from the center to the front surface of the weld metal, resulting in a solidification form that is prone to cracking. On the other hand, when the LTorch distance between electrodes is large, the columnar crystal associate angle at the front surface of the weld metal becomes smaller than 180°, indicating that the solidification form is less prone to cracking. This confirms that a solidification form that is less prone to cracking is formed under conditions where the distance between electrodes is relatively large.It was confirmed that a large tensile plastic strain increment in BTR of more than 3.0% occurred at the surface of the weld metal when the electrode distance LTorch was small and that the increment was <2.7% when the electrode distance LTorch was large.