Introduction to Welding Engineering

Join similar or dissimilar materials with or without heat and pressure; metallurgical changes and oxidation influence weldability, with homogeneous welds when filler matches base material, and wear a helmet.

Learn metallurgy in welding by analyzing how heat input and cooling govern weld microstructure, heat-affected zones, diffusion, grain growth, and porosity.

Explore bead geometry in welding, showing how heat deposits liquid metal to form penetration and a bead, and define dilution percentage as deposition area over penetration plus deposition areas.

Explore five welding process classifications, including gas welding (oxy-acetylene, oxy-hydrogen), radiant energy welding (electron beam, laser beam), and solid-state welding (friction, ultrasonic, diffusion bonding, explosive).

The lecture explains transformer behavior with constant current and constant voltage power sources, showing how load changes influence output, and discusses open-circuit and short-circuit currents, tapping to prevent aglow.

Explore modeling a power source as a line with open-circuit voltage and current, and determine the optimum operating point for maximum power by differentiating the power with respect to voltage.

Learn the basics of arc welding, including electric discharge and electrode heat that fuse base metals into a molten joint. Understand shielded metal arc welding, polarity, and key process parameters.

Explore arc welding polarity and how direct current electrode positive or negative, and alternating current, influence cleaning action, fusion, penetration, and defect risk on various base metals.

Solve a numerical welding problem to find the welding speed that yields the highest cooling rate by maximizing melting and heat transfer efficiency, given a six millimetre square cross-section.

Explore gas tungsten arc welding, using a non-consumable tungsten electrode and inert shielding gas to join metals, with alternating or direct current power and applications in aerospace and automotive.

Explore metal inert gas welding (mig) with a dc arc and fed electrode wire shielded by inert gas to form a weld pool; study short-circuit, globular, and spray transfer modes.

Submerged arc welding uses a continuously fed consumable electrode and gravity-fed granular flux to create a protective gas shield and slag, delivering deep penetration and good toughness with uniform properties.

Utilize plasma arc welding by using an inert shielding gas and a non-consumable electrode to create a high-energy plasma jet that achieves keyhole penetration in high-melting-point metals.

Electro slag welding uses heat from a current between a consumable electrode and the workpiece, with flux forming slag and a molten pool for vertical welding of plates in ships.

Examine electrodes, electrode coatings, and gas cutting, and learn how consumables are classified by coating and current type, with deposition characteristics and implications for contamination and molten metal behavior.

Learn the basics of the oxy-acetylene welding technique, including gas mixing, flame generation, base metal preparation, filler rod use, and controlled heating to join metals.

Explore neutral, reducing, and oxidizing flames in gas welding, and learn how each flame type affects heat, carbon interaction, and material suitability—oxidizing flame is not used for steel.

Explore resistance welding, where heat from electrical resistance across two components creates the joint. Examine factors like contact resistance, material thermal conductivity, heat rise, and current influences.

Spot welding joins two sheets by pressing with electrodes and passing current, creating a molten nugget at the interface that re-forms as it cools, used in automotive manufacturing.

Explore the numerical analysis of the spot welding process, linking current, time, nugget diameter, and latent heat of fusion with nugget volume, density, and resistance to predict weld outcomes.

Projection welding uses projections to localize heat and fuse sheet metals under pressure. It mirrors spot welding but uses flat copper plates to reduce current and pressure for efficient jointing.

Seam welding uses continuous electrodes and high current to join overlapping sheets, producing airtight, leak-proof seams by melting interface surfaces and maintaining controlled heat with cooling.

Flash butt welding clamps workpieces, passes high current to heat the joint, and applies force to form a weld while expelling impurities through the flash, for pipes and tubular shapes.

Friction welding is a solid-state joining method that uses friction and pressure to generate heat and forge joints through surface rubbing, enabling coalescence without melting, and preventing gas entrapment.

Explore friction stir welding as a solid-state joining method for aerospace alloys, focusing on microstructure, grain size, and mechanical properties in aluminum and titanium for airframes and space vehicles.

Describes the ultrasonic welding process, detailing the frequency converter, transducer, and horn, and how high-frequency vibration breaks oxide layers to form metal contact for joining wire connectors.

Explore explosive welding, a method that bonds plates via detonated charges to form an interlocking joint; enables heat exchangers, pipe joints, dissimilar-metal cladding, and requires safe handling by trained personnel.

Master electron beam welding, using high-energy electrons to create deep, narrow welds with minimal heat-affected zones in metals. Vacuum chambers and keyhole phenomena enable control for aerospace and automotive uses.

Learn laser beam welding for high-quality results with minimal distortion and shrinkage, and automate welding on materials up to 25 mm thick.