GMAW Fundamentals Quiz

Fundamentals of Gas Metal Arc Welding (GMAW)

• GMAW requires a gas supply with a flow rate of 28-50 cfh and specific equipment such as a cylinder, pressure regulator, and flowmeter.
• Metal transfer modes in GMAW depend on power level, shielding gas type, power source controls, and output.
• There are four basic metal transfer modes: spray, globular, short circuiting, and pulsed, each with different characteristics and applications.
• Spray transfer mode requires 80% argon, minimum, and is suitable for high power, high deposition, flat position welding.
• Short circuiting transfer mode is excellent for sheet metal, open root, and out-of-position welding but may result in incomplete fusion in thick sections.
• Pulsed transfer mode is essentially an intermittent spray transfer, with one droplet per pulse, and can be used for the same applications as short circuiting, plus thick sections.
• Transition current is the current level above which spray transfer can be achieved.
• Electrode extension is a critical variable in GMAW, affecting deposition, fusion, and shielding effectiveness.
• GMAW advantages include high productivity, clean process, continuous filler metal feed, and the ability to weld most alloys.
• GMAW limitations include unsuitability for windy conditions, little tolerance for contamination, complexity of equipment, and consumable requirements.
• Potential discontinuities in GMAW include porosity, incomplete fusion, incomplete joint penetration, undercut, and cracking, each caused by various factors.
• GMAW is an effective and efficient process for welding steel armor, with the use of metal core electrodes resulting in improved overall weld quality and acceptable welds with little or no cleanup required.