Topic
Heat-affected zone
About: Heat-affected zone is a research topic. Over the lifetime, 18787 publications have been published within this topic receiving 231744 citations.
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TL;DR: In this article, a three-optical-route visual sensor was designed to capture the weld pool from three directions at the same time, and serials of clear and stable weld pool images were obtained.
Abstract: In this paper, visual sensing and penetration control in aluminum (Al) alloy pulse gas tungsten arc welding were researched. Firstly, a three-optical-route visual sensor was designed. The sensor can capture the weld pool from three directions at the same time. After analyzing the influences of different factors on weld pool image, serials of clear and stable weld pool images were obtained. Then, image processing technologies were developed to compute back topside weld pool geometry parameters. Wavelet transform and Canny operator were synthesized to get all edges in the weld pool image. After noise removal and calibration, the breaking edges of weld pool were obtained, and then piecewise curve fitting based on polynomial function were used to recover the whole weld pool edge. Lastly, proportional-integral-differential and a multiplex controller were designed to control penetration in welding process. Experiments proved that visual-based penetration control can insure welding quality well from weld pool width and reinforcement.
93 citations
TL;DR: In this paper, the development of mathematical equations using a three factor 5-level factorial technique to predict the geometry of weld bead in butt joint of austenitic stainless steel 304 sheet of 2.5 mm thickness is presented.
Abstract: Laser beam welding (LBW) is a field of growing importance in industry with respect to traditional welding methodologies due to lower dimension and shape distortion of components and greater processing velocity. Because of its high weld strength to weld size ratio, reliability and minimal heat affected zone, laser welding has become important for varied industrial applications. With increased use of laser welding in continuous mode, there will be increased dependence on the use of equations to predict the dimensions of the weld bead. In this paper, the development of mathematical equations using a three factor 5- level factorial technique to predict the geometry of weld bead in butt joint of austenitic stainless steel 304 sheet of 2.5 mm thickness are presented. The models developed have been checked for their significance by using F-test and t-test. The direct and interaction effect of the process variables on bead geometry are presented in graphical form for quick analysis.
93 citations
TL;DR: In this paper, the effects of laser welding process on the functional properties of NiTi and related alloys are investigated, and the impact of the post-weld heat treatment (PWHT) is studied as an effective solution to improve the downsides of the Laser welding process.
93 citations
TL;DR: In this article, the process characteristics of active flux tungsten inert gas welding and keyhole mode GTAW, two recent developments to GTAW are considered, as is keyholemode plasma arc welding, which is capable of greater penetration and faster processing speeds than conventional GTAW.
Abstract: Titanium alloys used in aerospace structures require joints of high integrity to meet the design requirements. Gas tungsten arc welding (GTAW), laser beam welding (LBW) and electron beam welding (EBW) are all processes capable of creating fusion welded joints. Gas tungsten arc welding offers the potential to achieve welds of equal quality to EBW or LBW at much lower capital costs; however, the application of GTAW involves gaining an understanding of the complex process characteristics. This paper reviews the process characteristics for GTAW titanium alloys and compares these characteristics with EBW and LBW titanium alloys. The characteristics of active flux tungsten inert gas welding and keyhole mode GTAW, two recent developments to GTAW, are considered, as is keyhole mode plasma arc welding. These variants are capable of greater penetration and, in some cases, faster processing speeds than conventional GTAW. Finally, the current knowledge of weld microstructural development in cast and wrought α...
93 citations
01 Jan 2011
TL;DR: In this article, the authors used mathematical models to systematically investigate the transport phenomena leading to the formation of porosity and to find possible solutions to reduce or eliminate porosity formation in laser welding.
Abstract: Porosity is detrimental to weld quality. Our previous study shows that porosity formation in laser welding is associated with the weld pool dynamics, keyhole collapse, and solidification processes. The objective of this paper is to use mathematical models to systematically investigate the transport phenomena leading to the formation of porosity and to find possible solutions to reduce or eliminate porosity formation in laser welding. The results indicate that the formation of porosity in pulsed laser welding is caused by two competing factors: one is the solidification rate of the molten metal and the other is the backfilling speed of the molten metal during the keyhole collapse process. Porosity will be formed in the final weld if the solidification rate of the molten metal exceeds the backfilling speed of liquid metal during the keyhole collapse and solidification processes. Porosity formation was found to be strongly related with the depth-to-width aspect ratio of the keyhole. The larger the ratio, the easier porosity will be formed, and the larger the size of the voids. Based on these studies, controlling the laser pulse profile is proposed to prevent/eliminate porosity formation in laser welding. Its effectiveness and limitations are demonstrated in the current studies. The model predictions are qualitatively consistent with reported experimental results. DOI: 10.1115/1.2724846
92 citations