Electric resistance welding

About: Electric resistance welding is a research topic. Over the lifetime, 16761 publications have been published within this topic receiving 154851 citations.

Study of friction stir welding of aluminum

Abstract: A half-cold hardening aluminum plate were friction-stir welded at various rotation speeds (850–1860 rpm) and travel rates of 30 to 160 mm/min with welding forces ranging between 2.5 and 10 MPa using different dimension welding heads. Experimental results show that the dimensions of the welding head are critical to produce sound welds. The microstructure of the weld is characterized by its much finer and equiaxed grains as contrasted with the coarse and band-like structure of the parent aluminum plate. Tensile strength of the welds is about 20% lower than that of the hardening aluminum plate, but about 10% higher microhardness is demonstrated by the welds in comparison with that of the aluminum plate in annealing condition. Moreover, travel rate of the welding head pin has a strong effect on microhardness and tensile strength of the FSW welds, and the ratio of rotation speed and travel rate of the head should be in a reasonable range to obtain high performance welds. The variables of the welding process are also discussed in terms of heat balance and energy input of the welds.

Short-circuit arc welding with constant beads

Abstract: In short circuit arc welding there are many parameters which influence the automatically controlled welding procedure, but which frequently may affect the quality of the weld. In some circumstances the welding bead which is formed does not flow in to the molten pool of the workpiece, but disintegrates into many small drops around the weld owing to an excessive short-circuit current. The invention proposes methods and arrangements in which certain parameters, such as arc time and a short-circuit current delay time are controlled or maintained constant, so that always a constant bead size is assured owing to a constant power, after which said bead of constant size is first partly introduced into the molten pool and subsequently the short-circuit current for separation is applied.

Modeling and experimental investigation of induction welding of thermoplastic composites and comparison with other welding processes

Abstract: A three-dimensional finite element model of the induction welding of carbon fiber/polyphenylene sulfide thermoplastic composites is developed. The model takes into account a stainless steel mesh heating element located at the interface of the two composite adherends to be welded. This heating element serves to localize the heating where it is needed most, i.e. at the weld interface. The magnetic, electrical, and thermal properties of the carbon fiber/polyphenylene sulfide composite and other materials are identified experimentally or estimated and implemented in the model. The model predicts the temperature–time curves during the heating of the composite and is used to define processing parameters leading to high-quality welded joints. The effect of the heating element size and input current on the thermal behavior is investigated, both experimentally and using the developed model. The welds quality is assessed through microscopic observations of the weld interfaces, mechanical testing, and observations of the fracture surfaces. A comparison with two other welding processes, namely resistance welding and ultrasonic welding is finally conducted.

Effect of oxygen content in He–O2 shielding gas on weld shape in ultra deep penetration TIG

Abstract: The effect of the shielding gas concentration on the weld shape was studied for the moving bead on plate TIG welding of SUS304 stainless steel under He–O2 mixed shielding. The small addition of oxygen to the helium base shielding gas can precisely control the oxygen content in a liquid pool and the weld shape. Oxygen is a surface active element for stainless steel. When the oxygen content in the liquid pool is above the critical value of ∼ 70 ppm, the weld shape suddenly changes from a wide shallow type to a deep narrow one due to the change in the Marangoni convection from the outward to inward direction on the liquid pool surface. Weld shape variations influenced by the welding parameters including welding speed, welding current and electrode tip work distance under pure He and He–0.4%O2 mixed gas shielding were systematically investigated. The investigation results showed that the final shape of the TIG weld depends to a large extent on the pattern and magnitude of the Marangoni convection on t...

Application of grey relational analysis for optimizing weld bead geometry parameters of pulsed current micro plasma arc welded inconel 625 sheets

Abstract: Pulsed current micro plasma arc welding (MPAW) is one of the most widely used welding processes in sheet metal manufacturing industry. In any fusion arc welding process, the weld bead geometry plays an important role in determining the mechanical properties of the weld and hence quality of the weld. Moreover, the geometry of weld bead involves several simultaneously multiple quality characteristics such as front width, back width, front height and back height, which must be closely monitored, controlled and optimised. This paper presents the optimization of the pulsed current MPAW process by using the grey relational analysis considering the aforementioned quality characteristics. The specific targets are maximum front width and back width, minimum front height and back height. Experiments were performed under different welding conditions such as peak current, base current, pulse frequency and pulse width using Inconel 625 sheets of 0.25 mm thick. A response surface method (RSM)-based central composite design (CCD) experimental design is used to conduct experiments. Optimal welding parameters were determined by the grey relational grade obtained from the grey relational analysis. Optimal results have been verified through confirmation experiments.