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Joining. Learning Objectives. After completing this lesson, students will be able to: Define the terms welding, brazing, and soldering Describe the basic principles of arc welding, electroslag welding, oxyfuel gas welding, and resistance welding processes
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Learning Objectives • After completing this lesson, students will be able to: • Define the terms welding, brazing, and soldering • Describe the basic principles of arc welding, electroslag welding, oxyfuel gas welding, and resistance welding processes • List some of the principal applications of brazing processes • Describe the principles of soldering processes and their applications
Setup and fundamentals of operation for shielded metal arc welding (SMAW). (a) Circuit diagram. (b) SMAW process
Operating principles for flux cored arc welding (FCAW) with (a) auxiliary gas shielding, and nozzles for (b) auxiliary gas-shielded and (c) self-shielding method
Sectional views of a typical torch assembly for GTAW. (a) Flow of shielding gas and cooling water. (b) Electrical circuit
Comparison of (a) nonconstricted arc, used in GTAW, with (b) constricted arc, used for plasma arc welding (PAW)
Seven weld-joint combinations made by electroslag welding (ESW). (a) Butt; square-groove weld. (b) Butt; square-groove weld, transition between two plates of different thicknesses. (c) Corner; square-groove weld. (d) T; square-groove weld. (e) Corner; fillet weld. (f) Double-T; two square-groove welds. (g) Modified butt; square-groove weld
Gas cylinders and regulators used in oxyfuel gas welding (OFW)
Setup of workpiece and electrodes for making a single spot weld
Setup of work metal and electrodes for making multiple spot welds using direct and series welding
Development of weld nugget during projection welding of embossed spherical projections
19 mm (0.75 in.) A-710 steel plate, submerged arc weld. Heat input: 3.0 MJ/m. Macrostructure shows the fusion zone, heat-affected zone, and base metal in a single-pass, bead-on-plate weld. 85 mL H2O + 15 mL HNO3 + 5 mL methanol. Original magnification: 3.5×
16 mm (5/8 in.) A-36 steel plate, multiple-pass shielded metal arc weld. Heat input: 1.3 MJ/m. Composite micrograph of the heat-affected zone showing (from left to right) base plate, tempered zone, partially transformed zone, fine-grain zone, coarse-grain zone, fusion line, and fusion zone. 2% nital. Original magnification: 30.6×
Edge of fusion zone of a weld. Gas porosity (dark areas) in fusion zone (upper left) and in heat-affected zone (bottom right). Original magnification: 25×
Lack of penetration in butt-welded joint in . in. thick steel plate
Insert fig. 22 pg. 31 Effect of desirable and undesirable fit up on soundness of welds in joints between steel sheets 1.524 mm (0.060 in.) thick. Poor fit-up of joints in the top three rows may also result in complete melt-through.
Soldering temperature ranges compared with base metal melting points