Assessment of the Heat Input Effect on the Distribution of Temperature Cycles in the HAZ of S460MC Welds in MAG Welding

Temperature cycles generated during welding have a significant effect on the changes in the HAZ of welds, regardless of whether these are changes in structure or mechanical properties; however, it is problematic to obtain temperature cycles with sufficient accuracy across the entire HAZ so that they can be generally taken and used in welding simulations and for real experiments of processes occurring in HAZ. In particular, for a study in a specific location, it is important to know the maximum temperature of the cycle and the cooling rate defined mainly by the parameter t8/5. No studies in which anybody tries to find a mathematical description defining the basic parameters of temperature cycles in the HAZ could be found in the performed research. Therefore, the study presented in this paper results in a mathematical description defining the dependence of achieved maximum temperature on the distance from the fusion line in the HAZ of S460MC welds and with heat input values in the interval from 8 to 14 kJ·cm−1. Moreover, this paper presents the influence of heat input value on the weld pool geometry, including the effect of heat input value on grain coarsening in the highly heated HAZ.

Reduced finite-volume model for the fast numerical calculation of the fluid flow in the melt pool in laser beam welding

In this paper we propose a reduced two-dimensional finite-volume model for the fast calculation of the melt flow. This model was used to determine the influence of the welding speed, viscosity in the melt and vapour flow inside of the keyhole on the fluid flow field, the temperature distribution, and the resulting weld-pool geometry for laser beam welding of aluminium. The reduced computational time resulting from this approach allows the fast qualitative investigation of different aspects of the melt flow over a wide range of parameters. It was found that the effect of viscosity within the melt is more pronounced for lower welding speeds whereas the effect of friction at the keyhole walls is more pronounced for higher welding speeds. The weld-pool geometry mainly depends on the welding speed.

Improved Welding Quality Prediction for Metal Inert Gas Welding using Artificial Intelligence

Welding is widely used by manufacturing engineers and production personnel to quickly and effectively set up manufacturing processes for new products. The MIG welding parameters are the most important factors affecting the quality, productivity and cost of welding. This paper presents the influence of welding parameters like welding current, welding voltage, Gas flow rate, wire feed rate, etc. on weld strength, ultimate tensile strength, and hardness of weld joint, weld pool geometry of various metal material during welding. By using DOE method, the parameters can be optimize and having the best parameters combination for target quality. The analysis from DOE method can give the significance of the parameters as it give effect to change of the quality and strength of product.

Investigation on Ultrashort Pulse Laser Welding of Dissimilar Metallic Materials Expending Phase-Lag Influence

When the femtosecond laser pulse is comparable to the electron relaxation time, the hyperbolic effect cannot be neglected in heat transfer analysis. The non-Fourier effect is considered for heat transfer analysis assuming finite delay in the development of temperature within the body. This delay is represented in terms of two relaxation times connected to heat flux and temperature gradient. In the present work, a 3D finite element-based heat transfer model is developed using a dual-phase-lag effect. Since the experimental basis of transient temperature distribution in ultrashort pulse laser is extremely difficult or nearly impossible, the model results have been validated with the literature reported results. Furthermore, the simulation of dissimilar fusion welding system treated by an ultrashort pulse laser is demonstrated. The typical characteristic of thermal behavior with the application of femtosecond fiber laser on welding of dissimilar aluminum alloy and stainless steel is presented. The model results in the form of computed isotherm are compared with the literature reported weld pool geometry for dissimilar materials. The feasibility of characteristic parameters like pulse frequency, pulse width, and relaxation times are assessed in this study. A clear guideline of the geometric shape and size of weld pool geometry and the peak temperature of the welding system corresponding to predictable laser parameters is the effective output from this study. Peak temperature reached in a very short interval of time (∼ nanosecond) is analogous to a high rate of heating or cooling that affects the microstructural changes, specifically the formation of intermetallic for dissimilar welding.

3D Weld Pool Surface Geometry Measurement with Adaptive Passive Vision Images

Monitoring weld pool geometry without the appropriate auxiliary light source remains challenging due to the interference from the intense arc light. In this work, a new software framework was developed to measure the key features related to welding pool three-dimensional (3D) geometry based on the two-dimensional (2D) passive vision images. It was found that the interference of the arc light on the weld pool image can be effectively controlled by adjusting the camera exposure time based on the decision made from machine learning classifier. Weld pool width, trailing length, and surface height (SH) were calculated in real time, and the result agreed with the measurement of the weld bead geometry. The method presented here established the foundation for real-time penetration monitoring and control.