TAMU ENTC 313 Final Exam Review correctly answered 2023 passed

TAMU ENTC 313 Final Exam ReviewCO2 shielding gas on FCAW - correct answer widely used, low cost, deep arc penetration, relatively inert at room temp., dissociates at arc temps., allow for oxidation in the weld pool. Textbook: 6.5-1 - 6.5-4 Ar-CO2 shielding gas for FCAW - correct answer allows for greater oxidation resistance, most common ratio is: 75% Ar, 25% CO2, generally gives welds higher tensile & yield strengths than welds of 100% CO2, spray mode mixture, Excessive amounts of filler materials (Mn, Si, Al) will change mech. properties: reducing toughness and ductility. Textbook: 6.5-4 Which transfer methods might occur simultaneously in GMAW - correct answer Spray transfer and globular transfer methods may occur simultaneously. Textbook: 6.6-1 - 6.6-2 GMAW Spray Transfer - correct answer High heat with rapid deposition of weld metal, droplets (less than or equal to diameter of electrode) that travel through arc to the work piece, inert shielding gas, mostly with DC+, recommended for metal 1/8"+ , okay for vertical and overhead, almost spatter free, deep weld penetration. Textbook: 6.6-1 GMAW Globular Transfer - correct answer molten ball (2-3 times electrode diameter) transfers across the arc, highly unstable, shielding gas has largest influence (less than 80% Ar = globular), lots of spatter, gravity is the greatest acting force. GMAW Pulsed-Spray Transfer - correct answer puling current back and forth between 2 levels, permits spray transfer at lower current levels, spray transfer in evenly spaced pulses, essentially spatter-free, two levels of current come from separate power sources, can be used on this materials and out of position Textbook: 6.6-1 GMAW Short Circuit Transfer - correct answer No metal transferred across arc, transfer occurs when electrode makes contact with work piece, metal is less fluid and less penetrating compared to spray arc, low currents. low wire feed speed, low voltage, small diameter filler wires, faster wire feed speed = more short circuits per sec., Textbook: 6.6-1 - 6.6-2 SAW alloy steel deposits - correct answer Made using flux type or cored metal wire Granulated Flux: alloying elements are powderized and mixed in with the flux, flux mixes with molten metal, and alloying elements become part of the weld. Cored Wire: alloying elements can be added to the core of the wire before it is formed and drawn out. When electrode melts, the core melts and becomes part of the weld Textbook: 5.2-1, 7.2-2 - 7.3-3