Study on Short-Circuiting GMAW Pool Behavior and Microstructure of the Weld with Different Waveform Control Methods

Abstract

In order to study internal relation among the behavior of the weld pool, the microstructure of weld bead and the waveform of short-circuiting gas metal arc welding (S-GMAW), a high speed photograph-images analysis system was formed to extract characteristics of weld pool behavior. Three representative waveform control methods were used to provide partly and fully penetrated weld pools and beads. It was found that the behavior of the weld pool was related to the instantaneous power density of the liquid bridge at the break-up time. Weld pool oscillation was triggered by the explosion of the liquid bridge, the natural oscillation frequencies were derived by the continuous wavelet transform. The change of weld pool state caused the transition of oscillation mode, and it led to different nature oscillation frequencies between partial and full penetration. Slags flow pattern could be an indication of the weld pool flow. Compared with the scattered slags on fully penetrated weld pool, slag particles accumulated on partially penetrated weld pools. The oscillating promoted the convection of the welding pool and resulted in larger melting width and depth, the grain size, and the content of pro-eutectoid ferrite in the weld microstructure of S235JR increased, the content of acicular ferrite decreased.

Fabrication and Characterization of Wire Arc Additively Manufactured AlSi5 Structures

“…The benefits of this technique include the possibility of manufacturing large size details with a significantly high accuracy and a high layer deposition rate in a controlled protective gas environment, which increases the quality of the formed structure. Two known variations of gas metal arc welding are most commonly employed in industrial applications-cold metal transfer (CMT) and cold arc pulse [11][12][13][14]. These studies indicate that the two methods are similar in that they strive to achieve the same goal through two slightly different approaches.…”

“…The high controllability of the two processes is what makes them ideal for automation and integration in complicated mechatronic devices such as fully automated robotic systems. The pulsing nature of the welding process leads to the formation of a smaller heat affected zone, which intern allows for the employment of the two methods for the welding of thin metal sheets, as well as light metal components such as aluminum which has one of the lowest melting temperatures amongst other metals [11][12][13][14].…”

A New Method to Assess Fiber Laser Welding Quality of Stainless Steel 304 Based on Machine Vision and Hidden Markov Models

“…The metal vapor and photoinduced plasma are highintensity interference light sources, which are difficult to achieve the ideal effect when shooting keyhole directly. Previous literature [27,35,43,44]and our attempts have shown that the use of lasers with a center wavelength of about 1070 nm and austenitic stainless steel, narrow band filters around 808 nm and auxiliary illumination lasers of the same wavelength can well suppress interference of photo-induced plasma and spatter. Due to the non-coaxial imaging configuration, the reflected light on the surface of the base material has little effect on the imaging and can be ignored.…”

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

“…To describe the nature of the arc burning, its stability, as well as identifying characteristic zones during arc burning (AEA-arc extinction area; SCA-short-circuiting area; ABA-arc burning area), the use of current and voltage cyclograms has become widespread [86,91,93]. Current and voltage cyclograms show welding voltage as a function of the welding current.…”