Copyright Goodheart-Willcox Co., Inc. 138 Gas Tungsten Arc Welding Handbook 4. Hold the welding rod as shown in Figure 8-13 and move it so the end is approximately 1″ (25.4 mm) from the electrode. 5. Start the arc at low current. Lower the torch so the electrode tip is approximately 1/16″ (1.6 mm) from the surface. 6. Increase the amperage and form a weld pool approximately 1/4″ (6.5 mm) in diameter. 7. Bring the rod into the front edge of the pool and melt enough rod to form a slight crown on the surface. 8. Draw the rod approximately 1/2″ (12.7 mm) away from the pool. 9. Move the torch forward approximately 3/16″ (4.8 mm) and add rod again as in Step 7. 10. Continue moving the arc across the joint, adding rod as before. 11. Stop the weld at the end of the plate. Remember to hold the torch at the end until the weld cools. This protects the weld with shielding gas as it cools. Problem Areas and Corrections: 1. Uneven top weld width and low crown. Possible cause: Variation in travel speed. Solution: Maintain a consistent travel speed. Possible cause: Heat buildup in the weld pool. Solution: Increase the travel speed as the plates get hotter. Possible cause: Variation in adding rod. Solution: Add rod to form a consistent crown. 2. Undercut. Possible cause: Torch not aligned vertically. Solution: Maintain a 90° work angle. Possible cause: Not enough filler metal added to the weld pool. Solution: Add rod to the center of the weld pool. 3. Penetration uneven or lack of penetration. Possible cause: Inconsistent travel speed. Solution: Maintain a consistent travel speed. Possible cause: Inconsistent rod addition. Solution: Add filler metal to create a consistent crown on the weld pool. Possible cause: Insufficient amperage. Solution: Increase amperage and add more welding rod. Possible cause: Inconsistent torch height. Solution: Hold the torch at a consistent height. Welding Procedure Number 8-3 Weld joint type: Square-groove butt Position: Flat Material type: Cold-rolled steel Thickness: 1/16″ (1.6 mm) Filler metal: ER70S-2 or 6 Diameter: .045″–.062″ (1.1 mm – 1.6 mm) Machine setup: DCEN high-frequency start Shielding gas: Argon CFH: 15–25 Tungsten type: 1%, 1.5%, or 2% lanthanated, ceriated, or thoriated Diameter: 1/16″ (1.6 mm) (tapered) Procedure: 1. Prepare and clean the materials. 2. Tack weld the plates together. 3. Raise the part to be welded 1/8″ (3.2 mm) above the table with metal blocks. 4. Align the torch to the angles shown in Figure 8-14 and lower the torch until the electrode tip is approximately 1/8″ (3.2 mm) from the surface. 5. Position the end of the welding rod approximately 1″ (25.4 mm) from the electrode. Figure 8-14. Torch position for a square-groove butt weld in the flat position. (Mark Prosser)