CWB Module 4 Welding Processes Exam 2025

What is E4918-X? - - E=Electrode 49= tensile strength 1=position (1=all, 2=Horiz Fillet & Flat, 4=vert down) 8=coating type -X= optional improved toughness What are the three Coating Type Classes? - - EXX10 & EXX11 = Cellulose EXX12, EXX13, EXX14 = Titania EXX15, EXX16, EXX18 = Basic What type of electrodes are prone to moisture absorption? - -Basic What is E308-16? - - E=Electrode 308=Alloy Type 1=Position 6=Flux Type What is Deposition? - -the amount of weld deposited in a given period of time. Amp's do the melting. What would you use large diameter electrodes to weld? - -Thick Materials or in the flat position What would you use smaller diameter electrodes to weld? - -Thin Materials, Roots or out of position What does Iron Powder in the flux do? - -Increases deposition rates What does Nickle do to the weld? - -Improved Notch Touchness When welding SMAW, what degree should the electrode be? - -5° to 10° What type of shielding gas is used for GMAW? - -CO2 or oxygen What type of power output is GMAW typically? - -DCEP constant voltage Are Amps and Volts Higher or Lower with short arc length? - -Higher Amps, Lower Volts CWB CWB CWB What are the different modes of GMAW? - -Short Circuiting Globular Spray Transfer What is Short Circuiting GMAW? - -- pinches off droplets (more than 100/droplet) - runs cold (amperage is low) - high current causes spatter - used mostly on cast irons - 100% Oxygen or 75% Argon/25% CO2 What are some characteristics of Globular Transfer GMAW? - -- irregular shape due to droplets splashing in weld pool - Higher Current gives better penetration - 100% Oxygen or 75% Argon/25% CO2 What are some characteristics of Spray Transfer GMAW? - -- Continuous stream of droplets - Minimal Spatter - Relatively quiet and smooth arc - Good penetration and appearance - Large weld pool so not ideal for Out of position - Good for thick material - Droplets are typically less than wire diameter - Hot/Fast/Smooth - Argon rich gas (min 85%) What are some characteristics of Pulsed Transfer GMAW? - -- No Spatter/thin materials - Good for aluminum and all positions. - Out of Position capability - larger diameter electrode can be used What is the transition current (Current at which mode of transfer changes) dependent on? - -wire diameter, shielding gas, electrode, and electrical What are some advantages to GMAW? - -- higher disposition rates and productivity - higher duty cycle - save time on slag clean up - higher utilization of filler metals What is a disadvantage to GMAW? - -- It's sensitive to weld parameters What are the three common shielding gases to weld carbon and alloy steels? - -- Carbon dioxide - Argon-Carbon dioxide - Argon Oxygen CWB CWB What are some characteristics of Argon? - -- low ionization potential - low thermal conductivity What type of power output is FCAW? - -DCEP Constant Voltage What are some advantages to FCAW? - -- high quality weld - high disposition rates - more tolerant to parameter changes and contaminants - Good penetration - Out of position welding What are some disadvantages to FCAW? - -- lots of fumes - Slag Removal What is the ideal welder technique for FCAW? - -20° to 30° drag (pull) What is a good power output for SAW? - -DCEP - provides good bead control and deeper penetration (most common) DPEN - Less Penetration with more flaws What are some advantages to SAW? - -- high productivity, high disposition, high duty cycle - Low hydrogen process Dis - flat and horizontal positions only What are the two types of flux? - -Fused and Bonded How is Fused Flux Made? - -by melting together various ingredients, place on a chill table, crushed and screened - resistant to moisture - easy to recycle - difficult to add deoxidizers How is Bonded Flux Made? - -Finely grind individual components, mix, add binder (potassium), bake, ground to size - easy to add deoxidizers - prone to pick up moisture What are three types of flux? - -Basic - Calcium & Manganese oxide Acidic - Silicon oxide Neutral - he ratio of Basic and Acidic are equal Where do the mechanical properties come from with SAW? - -The flux CWB CWB What is resistance welding (RW)? - -Electrodes are placed in contact with the material, and electrical resistance heating is used to raise the temperature of the workpieces and the interface between them. The same copper electrodes that supply the current also apply the pressure - Fluxes and filler metals are not generally used - good for carbon steels and Stainless steels What is Electro Slag Welding (EBW)? - -- heat is generated by the electrical resistance of the molten slag. Melts the base metal and the consumable - electrode is fed through a guide tube to the bottom of a vertical joint, side walls are parallel tot he electrode. Arc is initiated under a bed of flux. Flux becomes molten to make a slag bath. Arc extinguishes once molten slag is formed - has a consumable tube - material from 75mm to 300mm thick What is Diffusion welding (DW)? - -- produces an atomic bond between two surfaces with pressure and heat - joining happens below melting point contacting surfaces is produced at loads insufficient to cause micro deformation - brittle surface oxides are removed for atom migration - occurs through 3 stages metallurgical sequence: deformation, diffusion at grains, volume diffusion at atoms What is Explosion Welding (EXW)? - -produced through high speed impacting of two or more material - no extreme heat transfer - can be higher hardness Welding is a joining process that by definition requires the application of: A) both heat and pressure B) either heat or pressure C) both heat and filler metal D) both pressure and filler metal E) all of the above - -C) Both heat and filler metal Name two main methods of arc shielding. - -gases, flux In which direction do the electrons flow in an electrical arc - from anode to cathode or from cathode to anode? - -Cathode to Anode In arc welding, the electric arc is intensely hot with temperatures exceeding: A) 20000°C B) 30000°C C) 33000°C D) 40000°C - -B) 30000°C CWB CWB Which are welding process has the highest arc efficiency? What is its approximate value? - -SAW 90% to 95% How do the arc voltage and arc stiffness change when the arc length is increased? - Voltage is increased , Arc stiffness decreases What is the generic name for the electrode used in GTAW and does it melt to provide filler meal for the weld? - -Non Consumable and No In the GTAW process, what type of penetration and weld width can be expected when using DCEP? - -Shallow Penetration, wide weld width Which polarity is chosen most often fro DC GTAW of steels and why? - -DCEN - more heat at the work piece causing deeper penetration Why must the shielding gas for GTAW be completely inert? - -oxygen and carbon dioxide will oxidize the tungsten State two advantages of GTAW process. - -- high quality - high deposition - welds all metals and alloys