 April 2006FEATURES Back to Basics: Using a Buried Gas Metal Arc for Seam Welds At the present time, gas metal arc welding (GMAW) is the primary process used for joining relatively thin (1–4.5 mm) parts in the automotive industry, through fillet welds in lap (Figs. 1C, 4) and T joints, and square groove butt joints (Fig. 1A). One drawback to GMA welding these joints, especially with mechanized (robotic or track-driven) systems, is the need to position the welding torch so the wire tip and arc are laterally placed within ±0.5 mm of the joint edge being welded. To accommodate this requirement, one or a combination of the following approaches is employed: 1) Use of dimensionally accurate parts and fixtures, which adds significantly to the final cost of the assemblies. 2) Employment of torch/arc oscillation relative to the joint edges, thus compensating for unplanned variations in jointedge location in space, location of parts by welding fixtures and/or positioners, and lateral placement of wire tip and arc, by the robot, relative to the joints. I. Stol et al. What's Up with Wire Feeders? The most significant developments in wire feeder technology over the past five years primarily fall into two categories: microprocessors and improved wire feeding technology. At least that’s the concensus of a variety of wire feeder manufacturers. The Welding Journal recently queried manufacturers regarding the future of wire feeder technology, the features they consider most important for producing high-quality welds, and how to meet the specific wire feeding needs for welding with solid wire, metal cored wire, and aluminum. Representatives from ESAB Welding & Cutting Products, Florence, S.C.; The Lincoln Electric Co., Cleveland, Ohio; Miller Electric Mfg. Co., Appleton, Wis.; MK Products, Inc., Irvine, Calif.; and Panasonic Factory Solutions Co. of America, Buffalo Grove, Ill., responded. M. R. Johnsen et al. Joining Dissimilar Aluminum Alloys Friction stir welding (FSW) is a novel joining process invented and patented at TWI in 1991 (Ref. 1). Since the mechanism and merits of FSW have been covered in previous literature, they are not described in detail in this paper. The applications of FSW have been reported and commercialized in many industrial sectors, especially in transportation, e.g., ships (Ref. 2), railway cars (Ref. 3), automobiles, airplanes and rocket fuel tanks (Ref. 4). The mass of aluminum is about one third that of steel, and for structural components, it is about one half of steel. Therefore, weight reduction of structural parts will be an important challenge in the automotive industry for improved fuel economy. K. Okamoto et al. Welding Aluminum Pipe and Tube with Variable ILinde BOC Process Plants, LLC fabricates piping and vessels to the requirements of oxygen clean service. These production systems are required to produce, store, and distribute liquid or gaseous oxygen, nitrogen, and argon, to strict cleanliness standards. All greases, lubricants, moisture and welding spatter or flux must be excluded, or removed from these systems prior to being placed into service. In addition, highly skilled aluminum welders are trained and qualified to make consistent, X-ray quality welds. R. Wilsdorf et al. THE AMERICAN WELDER Going Nuclear The largest construction project in the United States, the “Vit” project, as it is known locally, will involve pipe welding of an extraordinary magnitude: more than two million feet of process and cross-country pipe. The problem is that the large amount of pipe that needs welding may exceed the number of qualified welders locally available. (More information on the project is available on the official project Web site, www.waste2glass.com.) With no nuclear plants built in more than 25 years, the scope of pipe welders’ work has changed to serve the paper, food, and petrochemical industries. As a result, many lost the skills needed to weld nuclear pipe. N. Borchert A Brief History of Aluminum The Iron Age began about 3200 years ago when ancient blacksmiths separated iron from ores in crude clay and stone ovens. Iron tools were then hammered out on cast iron anvils. It was many years later that iron was alloyed with carbon to create steel. So, on the metallurgical time scale, aluminum is comparatively new. From Pickling Salt to Aluminum The base ore of aluminum, known as bauxite, was in use for much longer though, as alum pickling salt. E. Starkey Sister and Brother Team Study Welding Erika, 22, became interested in welding while attending Stockbridge High School in Stockbridge, Mich. In her freshman year, she took the introduction to technology class. Her teacher, Duane Watson, encouraged her to take the manufacturing technology class in her sophomore year. “He told me that there was welding in it along with some other things, and that kind of sparked my interest,” she said. “I didn’t know anything about welding.” K. Campbell WELDING RESEARCH SUPPLEMENT *Microstructure and microchemistry of Hard Zone in Dissimilar Weldments of Cr-Mo Steels (.pdf) The microstructure and microchemistry of hard and soft zones in dissimilar weldments of Cr-Mo steels that underwent postweld heat treatment are reported. C. Sudha et al.
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