The exothermic cutting process uses exothermic reactions for cutting, piercing, or gouging almost any ferrous or non-ferrous material including iron, steel, magnesium, and aluminum. An exothermic torch produces intense heat through the reaction of oxygen with a consumable fuel rod, typically made of steel or other ferrous materials.

Destructive weld testing involves the physical destruction of a completed weld to evaluate its strength and characteristics. The testing procedure is conducted to understand a specimen’s material behavior, strength, quality of the welded joint, and the skill of the welder.  

Air carbon arc gouging is a thermal cutting process of removing or severing metal by heat from a carbon arc. The process uses a carbon/graphite electrode, a standard power source, and compressed air. The intense heat arc produced between the tip of the electrode and the metal workpiece melts and cuts the metal.

A battery-powered welder is a portable welding machine that operates using lithium-ion (Li-ion) batteries as its primary power source. These welders are designed for convenience, mobility, and use in remote or off-grid locations where access to power is limited or non-existent. They don't require heavy or expensive welding cables or extension cords. 

In oxy-fuel cutting, a mixture of fuel gases and oxygen is used to cut metals. Some of the commonly used fuel gases include propane, natural gas, acetylene, and a few other mixed gases. This technique is immensely popular on CNC (Computer Numerical Control) machines for cutting steel plates.

Alloying elements are added to welding filler metals and base metals to achieve specific mechanical properties, improve weld quality, and enhance performance in different environments. These elements affect the strength, hardness, corrosion resistance, ductility, and toughness of the welded joint. Some of the common alloying elements include silicon, copper, manganese, zinc, molybdenum, nickel, chromium, and carbon.

Welding processes involve high heat, electric arc, flame, and shielding gases which can pose risks to operators at the workplace. Some common welding hazards include fire, explosion, electrical shock, exposure to fumes, UV and IR radiation, high noise, burns, and cuts. 

Let us learn the difference between welding, brazing, and soldering. Welding is the process of joining two or more metals by melting and fusing using high heat, usually with the addition of welding filler metals and shielding gases.

In brazing, two or more materials are joined by melting a filler metal into the joints of the base materials to create strong bonds. Brazing doesn’t melt the base metals. Soldering also involves the joining of metals by melting a filler metal into the joints of the base materials. However, this process is carried out at a temperature below 840°F, which is much lower than the welding and brazing temperatures. 
 

AC (Alternating Current) welding involves using an alternating current in welding. AC current reverses its direction many times per second. DC (Direct Current) welding involves using a direct current with constant polarity flow in one direction. AC welding is typically used for aluminum, heavy plates, and certain types of materials that require alternating current. DC welding is more common and provides a smoother and more stable arc suitable for welding thinner metals. 

Porosity or wormhole welds occur when air or gas bubbles get trapped in the weld. The entrapped gases weaken the weld joint resulting in welding defects. Cleaning the weld surface, preheating, using the correct electrodes and welding parameters, as well as the correct welding speed and current settings, and regularly checking for any moisture contamination in the shielding gas cylinder are some of the factors that can help prevent porosity in welding. 

Weld cracks can occur due to rapid cooling, excessive stress, poor joint design, incomplete fusion, improper shielding gas usage, and contaminated base metals. It is important to use proper preheating, the correct welding speed and current, to avoid sharp angles, and reduce stress on the weld. 

Some common welding defects include weld crack, porosity, undercut, crater, overlap, spatter, lamellar tearing, incomplete fusion, incomplete penetration, slag inclusion, and distortion. Being mindful of these considerations while welding will help you better prevent defects in the future.

Welding defects are imperfections or irregularities within the weld. Improper welding techniques, contamination, not using the right shielding gas, and improper settings are some of the factors that cause defects in welds. 

Heat-affected zone (HAZ) in welding refers to the areas within the base metal that are not melted but have undergone structural changes due to high heat from welding.

In welding, a shielding gas is used to protect the molten metal from reacting with atmospheric gases. The most common shielding gases include carbon dioxide, helium, argon, and oxygen. The right selection of shielding gases ensures a smooth welding process for high-quality welds. 

Laser (Light Amplification by Stimulated Emission of Radiation) welding is a fusion welding process where metals or thermoplastics are joined using a focused laser beam. In the laser welding process, a highly concentrated beam of light is focused on the cavity between the materials to be joined. The powerful laser beam melts the materials at their seams and fuses into a joint. 

Pulse MIG welding, also known as Pulse Gas Metal Arc Welding (GMAW-P), is a highly controlled spray-transfer MIG process. It is a non-contact process between the electrode and the weld puddle. In a pulse MIG process, a droplet of molten metal forms at the end of the electrode per pulse which is pushed into the weld puddle. 

MIG (metal inert gas) and TIG (tungsten inert gas) use electric arc and shielding gas to join metals, but they have certain differences. MIG welding is easy to learn and operate. This process uses a consumable electrode and is ideal for welding thicker materials. TIG welding requires higher precision and control. This process uses a non-consumable electrode and is ideal for welding thin materials. 

The four main types of welding positions are the flat welding position, horizontal welding position, vertical welding position, and overhead welding position. 

• In flat welding position, the workpieces to be welded are placed flat. An electric arc is passed over the workpieces in a horizontal direction. The top surface of the joint is welded allowing the molten metal to flow downward into the joint groove or edges.
• In the horizontal position, the weld axis is roughly horizontal. The position is executed based on the type of weld. 
• In the vertical welding position, the joint is vertical to the ground, at an angle between 45° and 90°.
• The overhead welding position is done from the underside of the joint. In this position, the welding is done with the metal pieces above the welder. 
   

The five basic types of weld joints are the butt joint, lap joint, edge joint, tee joint, and corner joint.

• A butt joint is formed when workpieces are put in parallel, and the side of each workpiece is joined by welding. 
• Lap joints are formed when two workpieces are stacked in an overlapping pattern on top of each other.  
• In Edge joint welding, the workpieces are joined together and welded at an edge point.
• A Tee joint weld form is made when two workpieces meet at a 90-degree angle. The edges of the components or the plate make a ‘T’ shape when joined in the middle. 
• Corner joints are made when two workpieces are joined and welded from 90° to an L shape. 

The four main types of welding are Gas Metal Arc Welding (GMAW), Shielded Metal Arc Welding (SMAW), Flux-Cored Arc Welding (FCAW), and Gas Tungsten Arc Welding (GTAW).

• The gas metal arc welding (GMAW), also known as MIG welding, uses an electric arc and consumable wire electrode to join metals. 
• Shielded metal arc welding (SMAW) is often referred to as stick welding. This manual welding process employs an electric arc and a flux-coated electrode to join metals.
• Flux-cored arc welding (FCAW) is also known as dual shield welding. The process uses a continuous, consumable tubular wire electrode filled with flux. FCAW process is highly efficient for welding thick materials. 
• Gas tungsten arc welding (GTAW) is also known as inert gas (TIG) welding. The process uses a non-consumable tungsten electrode.