Influence of the Welding Angle on the Mechanical Behavior of Plates obtained by the Tailor Welded Blank (TWB) Process

Tailor Welded Blank (TWB) is a top-welding technique (by unconventional processes) of sheets of different specifications (materials, thicknesses and/or coatings). Because it allows localised distribution of mechanical properties and mass, it can optimise the relationship between structural rigidity and total weight. The great challenge of this technique is to combine two processes with completely different demands, welding and mechanical forming. This work investigates the mechanical behavior of sheets obtained by the Tailor-blank process from the determination of the optimum angle. We performed tensile tests on sheets with different weld line inclinations, as the general objective is to consolidate knowledge about the process, characterise the conditions for sheet formation obtained by the technique, in a safe conformation range, with complex contours, dimensional qualities and free of catastrophic failure. Steel sheets, interstitial free (IF), of 1.10mm and 0.65mm thick were used. The TWB was applied with a welding line oriented from 0º to 90º (ranging from 15° to 15°). The optimum angle obtained was 30º, where there was a good relationship between the breaking load, purely tensile and shear stresses, and the total elongation. In relation to the angle of 0º, the optimum angle presented a superior elongation of approximately 40%. It was still possible to notice that the thickness of the plates influenced the optimum angle, even if the LSR (Limit Strength Ratio) is close.

Effect of casting and rolling process parameters on solidification welding line of magnesium alloy

Process of horizontal twin roll casting magnesium alloy was analyzed by numerical simulation. Taking solidification welding line in cast rolling area as research object, the characteristic change of solidification welding line caused by casting rolling temperature, casting rolling speed and roll heat transfer capacity and its influence on the forming process of casting rolling area were analyzed. The results show that increasing casting temperature, casting speed or reducing heat transfer capacity of roll can make solidification welding line shift to exit of casting rolling zone. Increasing casting temperature and casting speed will increase difference between middle and edge of the solidification welding line along casting direction. And heat distribution of whole slab is more uniform. However, effect of improving heat transfer capacity of roll is completely opposite. According to this, optimum process parameters of casting and rolling magnesium alloy with plate thickness of 6 mm are put forward to reduce probability of edge crack.

A COMPARISON OF DIFFERENT NUMERICAL APPROACHES FOR FSW WELDS OF API 5L - X80 STEEL

This contribution offers a study for two numerical approaches of FSW joints for the API 5L-X80 steel. The first one, a pure thermal model, takes into consideration the preponderant frictional force of the tool being in contact with the workpiece. The second model is a computational fluid dynamic approach, which involves determining experimental values for physical constants and observing its influence in viscous dissipation and strain rates of the material. Temperature and thermal history from the FSW processing were recorded and analyzed. The acquired data was provided from two different heat input conditions. In cases of previewing tool or workpiece local temperature, the pure thermal model is a sufficient suitable approach. Conversely, the CFD model frequently requires huge amounts of information, regarding physical constants and experimental variables, becoming a delicate task for its construction. The pure thermal model was able to offer unequivocal temperature results without the need for large experimental data acquisition. This approach was considered to be finer employed when one aims to forecast temperatures in regions proximate to the welding line. The natural complexity associated with FSW processing suggests there are enormous quantities of experimental factors to be considered for the numerical modeling of high-temperature materials. Also, the CFD approach offers distinct results, which might be crucial for understanding the full aspects of experimental variables. A coupled numerical approach with both models is suggested to fully represent the thermophysical aspects of FSW processing.

Experimental Study of the Performance of Base Metal and Welding Line of the Household LPG Cylinder Manufactured in Kurdistan Region

Liquefied petroleum gas (propane or butane) is a colourless liquid which readily evaporates into a gas. It has no smell, although it will normally have an odour added to help detect leaks. Liquefied petroleum gas is stored and handled as a liquid when under pressure inside an LPG cylinder. Liquefied petroleum gas cylinders are subjected to various tests to ensure their compliance requirements as per standard. This research studied the durability of welding and performance of base metal of LPG home cylindrical in Kurdistan region. The experiments were carried out on an unformed plate and three types of LPG cylinder designated as A, B, and C and D. In this research standard tests for LPG cylinders were conducted. Three samples were extracted from each of LPG cylinders and unformed plate for each of tensile test, bending test and hardness test according to ISO 6892-2016 and ASME standards to examine the mechanical properties. In addition, chemical compositions also were carried out. These values are compared with standard.

A Connection Method between Ultrahard PtW8 Wire and a Au Thick Film Based on Parallel-Gap Resistance Microwelding

To meet the application requirements of a thermal gas sensor, it is necessary to realize a bond connection between PtW8 wire with a Au thick film. However, the physical properties, such as the melting point and hardness, of the two materials differ greatly. In this study, the parallel-gap resistance microwelding was introduced into the bonding connection between PtW8 wire and a Au thick film in the thermal gas sensor. The feasibility of the method was analyzed theoretically and the experimental system was established and studied. A scanning electron microscope (SEM) was used to analyze the morphology of the cross-section of the welded joint. The results showed that there was no obvious transition layer at the interface region but there were relatively dense welds. At the same time, it was found that the melted Au wetted and climbed on the surface of the platinum-tungsten alloy, which may have been the key to forming the joint. Elements were observed to have a spatial distribution gradient within the cross-section of the welding line, revealing that mutual diffusion occurred in the parallel-gap resistance microwelding, where this diffusion behavior may be the basic condition for forming the joint. Finally, the influence of the welding voltage, time, and force on the joint strength was also studied, where the joint strength could be up to 5 cN.