Weld forming

I. Berman J.W. Schroeder, Eds, Explosive Welding, Forming, Plugging, and Compaction , The American Society of Mechanical Engineers, New York, NY (1980)... 

Blazynski, T. Z., Explosive Welding, Form, and Compaction, Applied Science Publ., London,... 

When two surfaces made from the same thermoplastic have to be joined, welding is the preferred method. There are several ways in which welding can be accomplished, but they all depend upon melting the surfaces to be joined, and bringing them together under pressure. During this operation, melted material flows outwards from the weld, forming a bead on the side of the component, as illustrated in Fig. 8.8. 

When the side wall of bottom-comer welds forms a right angle with the bottom, the fillet weld is seldom as smooth as shown in Fig. 11.24((j). It is usually rough and frequently varies in width... 

This semicommercial alloy was developed by RMI in a program sponsored by the Air Force Materials Laboratory in the early 1970s for use in aircraft components subjected to prolonged exposure near 500 °C (930 °F). It is a beta-lean a- 3 alloy with relatively low content of -stabilizing elements. Ti-5522-S exhibits good tensile, stress rupture, and creep properties at elevated temperature into the 425 to 540 °C (800 to 1000 °F) range. It can be welded, formed at room temperatxu es, or warm formed temperatm es 540 to 700 °C (800 to 1300 F). 

Low Cr-Mo steels, when welded or when cooled rapidly from elevated temperatures, form hard, inherently brittle microstmctures consisting of martensite and bainite. These structures have limited capacity for plastic deformation and, thus, have low fracture toughness in the as-welded form. It is of prime importance in repair welding that the original ductility be restored to these air-hardenable materials by maintaining the proper preheat and postweld heat treatment requirements of the welding procedure. 

The rupture tests revealed that the burst strength of all of the tubes was not diminished by the environmental conditions. All of the materials which were tested appeared to be satisfactory, but type 316L stainless steel was chosen as the best construction material because its welding, forming, and brazing characteristics were found to be more suitable for the heat exchanger construction. 

The composition of an alloy alone does not ensure the quality of the product. Evaluation of resistance to corrosion in a given environment, adverse effects of corrosion products on utility or contents, susceptibility to a specific type of corrosion and fouling, and tendency to corrosion failure due to fabrication and assembly processes, such as welding, forming, machining, heat treatment, etc., are of prime importance for the selection of material. 

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