Analysis of the coefficient of linear relationship, generated by the exponential heating during the welding process for an A36 steel plate

The present study presents the relationship of temperature and deformation as well as the analysis of heat transfer and deformation produced during welding of a steel plate. The method consists of strategically welding a base metal plate (A-36) with a high-hardness filler material to obtain an overall increment in wear resistance. However, the thermal cycles generated during welding produced deformation, thus changing the flatness of the plate. Different sequences of welding were applied to obtain a relationship between the heat transfer and deformation. A filler material was applied to 100 holes (1/2” diameter and 8 mm depth) in a ½” steel plate. The temperature and deformation were measured for 3 different welding sequences. Plate 1 reached a final mean temperature of 467 °C and deformation of 0.016”, plate 2 reached 472.9 °C and -0.008”, and plate 3 reached 354.2 °C and 0.020”. The results indicate that the deformation is not function of the final temperature, instead the deformation is function of the slope of the curve temperature vs deformation. The behavior of the curve temperature vs deformation is linear for all cases studied, confirming the findings of the lowest deformation for plate 2 which exhibited the lowest slope.

Investigation of the Dynamic Response of a Multispot System at Joining Using Ultrasonic Welding

Ultrasonic welding is one of the most practical joining method for polymer composite materials and has been adapted in the aerospace and automotive industries. To effectively join polymer composite assemblies, it is critical to understand the dynamic response of the welding system so that sound heating generation and welding sequences in the ultrasonic welding of the assemblies can be properly obtained. This study presents a dynamic response model of a multi-spot configuration assembly using ultrasonic welding. Here, a dynamic model of joining a U-shaped carbon fiber reinforced thermoplastic composite part with a flat part is developed and analyzed through the ratio between the frequencies generated at different locations of the spot with respect to the edges of the assembly and the natural frequency. Finally, this ratio is correlated with the weld quality of the multiple spot configuration. Guidelines for designing multisport sequence are extracted. This study provides a method to design the welding sequence in ultrasonic welding of carbon fiber reinforced composites.

INFLUENCE OF TACK WELDS DISTRIBUTION AND WELDING SEQUENCE ON THE ANGULAR DISTORTION OF TIG WELDED JOINT

In this paper the influence of tack welds distribution and welding sequence on angular distortion of the Tungsten Inert Gas (TIG) welded joint was tested. Additionally, the effect of welding current on angular distortion was assessed. For research X2CrTiNb18 (AISI 441) stainless steel (2.5 mm thick) was chosen. During research specimens were prepared with different distributions of tack welds. Then they were welded by different welding sequences with the use of different welding current values. After welding the angular distortion of each specimen was measured by using the coordinate measuring machine. In the next step specimens were cut. Cross-sections were polished and the metallographic macroscopic testing was conducted to check the geometry of performed welds. Performed experiments allowed determining the optimal tack weld sequence and welding parameters for welding thin stainless steel sheets.

EFFECTS OF WELDING CURRENT AND SPEED ON RESIDUAL STRESS AND DISTORTION OF JOINING ST52 ROLLED PLATE IN DIFFERENT WELDING SEQUENCES

Welding is a process of permanent joining parts by different welding methods. Residual stress and distortion are the most common phenomena of this process. Reduction of the residual stresses, distortion and improving the quality of welding are the important subjects of this field. Determining and analyzing the residual stresses and distortion is the main step for these purposes. Welding sequences, speed and current are the most effective parameters of this process. In this study, effects of welding parameters such as welding speed and current, in order to reduce residual stress and distortion of welding ST52 rolled plate in different welding sequences have been studied with three-dimensional thermo-mechanical finite element model by means of ANSYS APDL. By comparing different considered situations, the most efficient welding methods with the least residual stress and distortion by considering different welding sequences have been suggested. It obtains that welding the ST52 rolled plate from edge to edge with higher current and lower speed is the best option in fatigue and load-bearing situations, and welding from the center to both sides simultaneously with lower current and higher speed is the best option for assembly problems.

Analytical Model for Angular Distortion in Multilayer Welding under Constraints

We propose an analytical model for the fast prediction of angular distortion that is caused by practical multilayer (or multi-pass) butt welding under constraints. To this end, the relationships between angular distortion, bead size, thickness, and degree of constraint are derived by analyzing the welding deformation mechanism and considering the bead-on-plate welding experimental results. Prediction curves are then obtained while considering the geometry of the butt welding joint. We verify the formulas through experiments under various constraint conditions, with different welding joint geometries, heat inputs, and thicknesses. The proposed model can not only predict angular distortion in butt joints of various shapes, but also allows for providing restraint methods and welding sequences for minimizing distortion.

Scale down Approach to Solve Distortion Problem in Case of Wind Turbine Tower Fabrication

Submerged arc welding (SAW) process is extensively used in major industrial application such as wind turbine towers and ship building industries for joining of larger thickness (~10 to 50mm) of similar and dissimilar materials. However, other joining processes are not popular to weld larger thickness compared to SAW. In welding, one of the major problems is distortion, which destroys the dimensional stability of the component, a major concern in manufacturing. Simulation of larger thickness component will increase the simulation time. Therefore, an attempt has been made to evaluate a 3 - dimensional finite element analysis (FEA) using SYSWELD to study the effect of the joining of two similar shells of High Strength Low Alloy (HSLA) steel through scale down model in the ratio of 10:1. To reduce the simulation time, the two shells of steel having 400mm diameter and 2mm thickness are modelled and simulated with single pass GMAW process using eight different welding sequences as per welding procedure specification (WPS) using SYSWELD. Results show the simulated welding sequence no. 4 has a considerable amount of reduction in distortion of 1.526 mm compared to that of other sequences. Welding sequence no. 4 is then followed by actual windmill tower fabrication, which resulted in reduced distortion level of 5 mm.