Welding Processes and Materials

Procédés et Matériels de Soudage

Introduction Générale à la Technologie du Soudage

• Manual arc welding utilizes consumable electrodes.
• Friction welding is not a fusion welding process.
• Code 114 is associated with welding using a gasless flux-cored electrode wire.

Soudage aux Gaz et Procédés Connexes

• A reducing flame should be used when welding mild steel with the oxy-fuel process.

Rappels d'Électronique

• Diodes and thyristors are electronic components commonly used in welding power source rectifier bridges.
• The main role of the thyristor is to rectify current and regulate welding intensity.
• Residual magnetism in a material causes arc deflection and fusion zone deviation.
• If the current increases from 100 to 200 amps, the voltage drop in the welding cable doubles.
• When a variable DC current is sent through a coil, the current takes time to rise from zero and then remains constant at a certain value.

L'Arc

• An electric arc emits electrons at the cathode.
• An electric arc experiences electron bombardment at the anode.
• Ohm's Law is represented as U = R x I.
• Magnetic blow is more significant in DC welding.

Sources de Courant Pour Le Soudage a L'Arc

• "Direct polarity" in welding refers to connecting the electrode to the negative pole of the welding current source.
• Rectifiers, generators coupled to a diesel motor, and inverters can produce direct current.
• When the electrical circuit is open, voltage (U) is maximum, and current (I) equals 0.

Introduction au Soudage a L'Arc Sous Protection Gazeuse

• In MAG welding of carbon and manganese carbon steels, the main purpose of inductance in the welding circuit is to reduce molten metal spatter.

Soudage TIG

• Carbon dioxide is suitable for welding non-alloyed steels
• High frequency devices in AC TIG welding help improve arc stability.
• In TIG welding, contact between the electrode and the part/weld pool should be avoided because it causes tungsten inclusions.
• Direct current, direct polarity, is used for welding stainless steels in TIG
• Tungsten electrodes contain lanthanum oxide to increase thermo-emissivity and electrode lifespan.

Soudage MIG/MAG et Fil Fourre

• The contact tube of a welding torch in MIG/MAG welding must be frequently checked for proper tightness to ensure correct current transfer to the filler wire.
• The ideal gas flow rate for MAG welding with a 12 mm nozzle is between 8 and 12 l/min.
• Copper coating on MAG welding filler wires helps facilitate current transmission from the contact tube.
• Carbon dioxide shielding gas enables short-circuit transfer in MIG-MAG welding.
• A short arc in MAG welding results in a higher metal deposition rate, deeper penetration, a convex bead shape, and angle welds
• Cored wire is a metal tube containing flux.
• Cored wire welding is more productive than solid wire due to its lower sensitivity to steel impurities, resistance to crater cracking, and enhanced weld metal ductility.
• Cored wires are suitable for a wide range of welding positions because they form a slag that holds the weld pool in place.
• Cored wire welding generally produces fewer spatters than solid wire welding.
• Welding with cored wire can cause greater amounts of fume.

Soudage Manuel Avec Electrodes Enrobees

• Basaltic is not a recognized type of coated electrode.
• Welding a full penetration butt joint with fixed 12 mm tubes on a horizontal axis requires the most dexterity using a coated electrode.
• Manual electrodes with a basic coating need to be baked before welding
• The rutile, basic, or acid characteristic of a manual arc welding electrode depends on the coating composition.

Soudage Sous Flux en Poudre

• Electrode E 42 3 B 32 H 5 has the best resilience and tenacity for building steel.
• Agglomerated fluxes exhibit the greatest capacity to provide alloying elements to the molten metal.
• Flux protects the weld pool, cleans the molten metal bath, and modifies the chemical composition.
• A drooping characteristic AC current source uses self-regulation of arc voltage by a closed-loop regulation system.
• Using AC on the second wire prevents arc disturbance in twin-wire submerged arc welding.

Soudage Par Résistance

• A button test is the most suitable for quality control of resistance spot welds in production
• Resistance welding of copper is only possible for thicknesses less than 1 mm, using tungsten or molybdenum insert electrodes.

Autres Procédés de Soudage

• Laser welding is not suitable for thick copper.
• Welding with electron beams and lasers can use filler metal to improve metallurgical weldability and compensate for small gaps.

Autres Procédés de Soudage

• Welding with explosion can achieve steel/aluminum bond.

Coupage et Procédés de Préparation des Bords

• In plasma cutting, the energy source is a DC electrode at the negative pole with transferred plasma.
• Insufficient nozzle-to-workpiece distance in oxy-fuel cutting will fuse the top edge of the cut.
• Flame cutting is not suitable for cutting stainless steels.
• A temperature where the fusion temperatures of products are greater than the reaction temperature, will make a alloys unsuitable for oxycutting.

Rechargement et Projection

• Submerged arc welding with DC electrode at the positive pole & submerged arc welding with strip in DC electrode at the negative pole are used for cladding.
• TIG hot wire welding and oxyacetylene welding are usable in overlaying.
• MIG welding isn't suitable for thermal spraying.

Procédés Totalement Mécanisés et Automatiques

• Using a MIG welding robot increases the duty cycle.

Brasage Fort et Brasage Tendre

• Palpation préalable cannot correct the trajectory during robotic welding.
• Resistance welding is the best process adapted for automation.
• Vacuum brazing can be done without flux.
• Hard soldering relies on similar edge preparations to gas welding, resulting in a stronger joint.
• Capillary action of a brazing alloy in a brazed joint works best with a small gap between parts (0.05 to 0.15 mm).

Procédés d'Assemblage des Plastiques

• Cold press welding isn't used to produce plastic materials