A-TIG welding of dissimilar P92 steel and 304H austenitic stainless steel: Mechanisms, microstructure and mechanical properties

Effect of preheating on the defects and microstructure in NG-GMA welding of 5083 Al-alloy

Welding is a major manufacturing process that joins two or more pieces of materials together through heating/mixing them followed by cooling/solidification. The goal of welding manufacturing is to join materials together to meet service requirements at lowest costs. Advanced welding manufacturing is to use scientific methods to realize this goal. This paper views advanced welding manufacturing as a three step approach: (1) pre-design that selects process and joint design based on available processes (properties, capabilities, and costs); (2) design that uses models to predict the result from a given set of welding parameters and minimizes a cost function for optimizing the welding parameters; and (3) real-time sensing and control that overcome the deviations of welding conditions from their nominal ones used in optimizing the welding parameters by adjusting the welding parameters based on such real-time sensing and feedback control. The paper analyzes how these three steps depend on process properties/capabilities, process innovations, predictive models, numerical models for fluid dynamics, numerical models for structures, real-time sensing, and dynamic control. The paper also identifies the challenges in obtaining ideal solutions and reviews/analyzes the existing efforts toward better solutions. Special attention and analysis have been given to (1) gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) as benchmark processes for penetration and materials filling; (2) keyhole plasma arc welding (PAW), keyhole-tungsten inert gas (K-TIG), and keyhole laser welding as improved/capable penetrative processes; (3) friction stir welding (FSW) as a special penetrative low heat input process; (4) alternating current (AC) GMAW and double-electrode GMAW as improved materials filling processes; (5) efforts in numerical modeling for fluid dynamics; (6) efforts in numerical modeling for structures; (7) challenges and efforts in seam tracking and weld pool monitoring; (8) challenges and efforts in monitoring of keyhole laser welding and FSW; and (9) efforts in advanced sensing, data fusion/sensor fusion, and process control using machine learning/deep learning, model predictive control (MPC), and adaptive control.

/pdf/advanced-welding-manufacturing-a-brief-analysis-and-review-z2yhnqybd1.pdf

Advanced Welding Manufacturing: A Brief Analysis and Review of Challenges and Solutions

Arc characteristics in alternating magnetic field assisted narrow gap pulsed GTAW

https://orbilu.uni.lu/bitstream/10993/40299/1/1-s2.0-S2351978919310297-main.pdf

Laser welding of dissimilar copper and aluminum sheets by shaping the laser pulses

5052 aluminum alloy and pure copper (T2) are joined, using a low heat input pulsed double-electrode gas metal arc welding (DE-GMAW)-brazing method with AlSi 12 filler metal. The effects of welding current (heat input) on the microstructure and mechanical behavior of the joints, which consist of Al-Al welding zone and Al-Cu brazing zone, are investigated. The Al-Cu welding zone mainly consists of α-Al solid solution and Al-Cu eutectic phase in coral-like shape. There exists a layer of Al 2 Cu intermetallic compound (IMC) in the Al-Cu brazing zone. Using the theory of thermal activation process, a quadratic relation between the thickness of the IMC layer and welding current intensity is derived. The experimental result supports this relationship. The shear strength of the Al-Cu joints first increases with the increase of the welding current (heat input), reaches a maximum of 17.66 MPa, and then decreases with the increase of the welding current due to the dispersion of the Al 2 Cu IMCs of large sizes in the Al alloy. Fracture of the Al-Cu lap joints occurs at three different positions, and the corresponding failure mechanisms are discussed according to the morphologies of fracture surfaces.

Microstructures and mechanical behavior of aluminum-copper lap joints

Arc characteristics and metal transfer behavior in narrow gap gas metal arc welding process

Effects of different activating fluxes on the surface tension of molten metal in gas tungsten arc welding

The invention belongs to the technical field of welding and provides a novel twin-wire bypass coupled arc efficient metal-inert gas (MIG) welding system. By the adoption of the twin-wire bypass coupled arc efficient MIG welding system, the problems that an existing twin-wire bypass coupled arc efficient MIG welding system is complex in structure and high in cost are solved. The twin-wire bypass coupled arc efficient MIG welding system comprises a welding power source and a dynamic voltage adjusting device. The dynamic voltage adjusting device comprises an invert unit, a filtering unit, a voltage transformation unit and a direct-current output unit. The invert unit is used for inverting direct currents output by the positive electrode of the welding power source into alternating currents. The filtering unit is used for filtering current higher harmonics output by the invert unit in the inverting process. The voltage transformation unit is used for converting the output voltage of the invert unit into the voltage equivalent to the compensation amount of the bypass voltage. The direct-current output unit is used for rectifying the alternating currents output by the voltage transformation unit into the direct currents and outputting the direct currents. Due to the fact that the welding system comprises the welding power source, the system structure is simplified, and the welding cost is reduced.

Twin-wire bypass coupled arc efficient metal-inert gas (MIG) welding system

Intelligent robotic welding is a trend in the development of welding manufacturing and has a great application prospective. Weld pool dynamics plays a vital role in assuring the production of high-quality welds. Precision measurement of the weld pool surface characteristics is a bottleneck for accurate control of weld penetration as well as for successful development of next-generation intelligent welding system. In this article, the current progress in arc welding pool sensing is detailed and challenges in weld pool measurement analyzed. The key factor that hinders the development of intelligent robotic welding systems is identified and the approaches that realize the intelligent welding are also discussed. Lastly, the trend of intelligent welding manufacturing is predicted.

Ming Zhu

Papers

Microstructures and mechanical behavior of aluminum-copper lap joints

Arc characteristics and metal transfer behavior in narrow gap gas metal arc welding process

Effects of different activating fluxes on the surface tension of molten metal in gas tungsten arc welding

Twin-wire bypass coupled arc efficient metal-inert gas (MIG) welding system

Progress and Trend in Intelligent Sensing and Control of Weld Pool in Arc Welding Process