Welding Fundamentals 6e, Textbook Page 178 (198 of 656)

3. Determine the correct current type, amperage, and polarity for each electrode. Set the proper current for E6010 on the welding machine. 4. Form two T-joints. Tack weld each T-joint three times on each side using E6010 electrodes. 5. A three-pass weld will be made. Clamp the T-joint so the weld can be made in the flat position. Refer to weld passes 1, 2, and 3 in Figure 12-18. 6. Weld the root pass using an E6010 electrode. Obtain penetration into the root. The weld pool should have a C shape at the leading edge. 7. Clean the slag from the first pass and read the weld. Change the current, arc length, or speed as required. 8. Weld a second pass using an E6010 electrode. Obtain good penetration into both the first pass and the base metal. Goodheart-Willcox Publisher Figure 12-18. This fillet weld shows a good example of the sequence a welder should use when making a multiple-pass weld. 1 2 3 4 5 6 Third layer—3 beads Second layer—2 beads First layer— 1 bead Goodheart-Willcox Publisher Figure 12-17. For a single weld bead, or the first weld bead on a multiple-pass fillet weld on thick metal, the electrode is held at a 45° work angle. A 10°–20° drag travel angle is used. 45° work angle 10°–20° drag angle Front view Side view 178 Section 2 Shielded Metal Arc Welding Copyright Goodheart-Willcox Co., Inc.

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3. Determine the correct current type, amperage, and polarity for each electrode. Set the proper current for E6010 on the welding machine. 4. Form two T-joints. Tack weld each T-joint three times on each side using E6010 electrodes. 5. A three-pass weld will be made. Clamp the T-joint so the weld can be made in the flat position. Refer to weld passes 1, 2, and 3 in Figure 12-18. 6. Weld the root pass using an E6010 electrode. Obtain penetration into the root. The weld pool should have a C shape at the leading edge. 7. Clean the slag from the first pass and read the weld. Change the current, arc length, or speed as required. 8. Weld a second pass using an E6010 electrode. Obtain good penetration into both the first pass and the base metal. Goodheart-Willcox Publisher Figure 12-18. This fillet weld shows a good example of the sequence a welder should use when making a multiple-pass weld. 1 2 3 4 5 6 Third layer—3 beads Second layer—2 beads First layer— 1 bead Goodheart-Willcox Publisher Figure 12-17. For a single weld bead, or the first weld bead on a multiple-pass fillet weld on thick metal, the electrode is held at a 45° work angle. A 10°–20° drag travel angle is used. 45° work angle 10°–20° drag angle Front view Side view 178 Section 2 Shielded Metal Arc Welding Copyright Goodheart-Willcox Co., Inc.

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Inspection: The fillet welds must be the correct size. A convex weld bead must be formed with smooth and evenly spaced ripples. No undercut is permitted. Butt Joint Metal less than 1/4″ (6.4 mm) thick is welded using a square-groove butt joint. No edge preparation is required. A bevel-, V-, J-, or U-groove joint is used on thicker metal. The root pass is the fi rst and most important weld pass. Complete penetration to the opposite side of the metal can occur only on this weld pass. A keyhole, an enlarged root opening, must be seen throughout the root pass to ensure penetration. Refer to Figure 12-20. Additional weld passes must fuse with the base metal and the previous weld beads. The weld toes must fuse with the surface of the base metal. No undercut should be seen. A butt weld may be made from one or both sides. See Figure 12-21. Double-bevel-groove welds are used to ensure 100% fusion and penetration when welding thick sections. Less electrode material and welder time is required to weld a double-bevel- groove weld than to make a single-bevel-groove weld. 9. Clean the slag from the second pass and read the weld. 10. Make any change needed to the weld current. Decide if a change is needed in electrode angle or travel speed. Weld a third pass using E6010 to complete the weld joint. This pass must obtain penetration into the first pass, into the second pass, and into the second piece of the base metal. A C-shaped weld pool should be visible. 11. Clean the slag and read the weld. The completed three-pass weld should have a total leg size of about 3/8″ (10 mm) and a 1/2″ (13 mm) weld face. 12. Repeat steps 5–11, but use E6013 electrodes. Set the proper polarity and current. Complete two fillet welds using E6013 electrodes. 13. Repeat steps 5–11 using 5/32″ (4.0 mm) iron powder electrodes, such as E6027. The fillet weld size will be larger because the electrode diameter is larger. Remember to change the polarity and current setting on the welding machine if needed. 14. Compare the ease or difficulty of running a bead with each electrode type. Compare any differences in the appearance of the different welds. First pass Second pass Third pass Keyhole Goodheart-Willcox Publisher Figure 12-19. Three weld passes were used on this fillet weld. Each weld bead was stopped at a different point to show its placement. The first weld pass was laid in the root or corner with equal coverage of both plates. The second weld pass penetrates one-half on the first weld bead and one-half on the horizontal part. The third weld pass was laid from the second weld pass up to the vertical part. Goodheart-Willcox Publisher Figure 12-20. This is a keyhole as seen looking down into a bevel-groove butt joint. The enlarged keyhole shows that both pieces are being melted. Chapter 12 SMAW: Flat Welding Position 179 Copyright Goodheart-Willcox Co., Inc.

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in position prior to the main welding of the joint. The tack welds become part of the completed weld. Tack welds must be done well, or a defect in the completed weld can result. A tack weld is often 1/2″–3/4″ (13 mm–20 mm) in length. It must have complete fusion, or melting, into both pieces of metal. It must have complete penetration. All slag must be removed after making the tack welds. Fillet Welding A fi llet weld may be made on a lap, inside corner, or T-joint. The legs of the fi llet are usually equal. Normally, the size of each leg is at least equal to the thickness of the metal. Lap Joint In a lap joint, the weld is made along an edge of one piece and the surface of another piece. The electrode holder is tilted about 20° from vertical in the direction of travel. This is a 20° drag travel angle. The electrode should point more toward the surface when welding thinner metal. This is not as necessary when welding thick metal. The electrode should be held at a 45° work angle when welding metal over 1/4″ (6.4 mm) thick. See Figure 12-17. After the arc is struck, lay a stringer bead deep into the root of the joint. A C-shaped weld pool should be created. A C shape at the leading edge of the weld pool indicates that both the edge and the surface are melting. Reduce the travel speed if the C shape does not form. A welder can determine the correct forward speed by watching the rear of the weld pool. It should be oval-shaped. Thick metal may require more than one weld pass. Each weld pass must be cleaned before the next weld pass is made. The correct sequence of the weld passes in a multiple-pass weld is suggested in Figure 12-18. A multiple-pass weld contains more than one layer. Each layer may contain more than one weld bead or weld pass. The fi nal pass may be a weave bead if the bead width is not too wide. Inside Corner or T-Joint A fi llet weld for an inside corner or T-joint is made along two adjacent surfaces. The electrode will have about a 20° drag travel angle and a 45° work angle. The fi rst weld pass must be made deeply into the weld root. The leading edge of the weld pool must be C-shaped. This ensures that fusion is occurring on both surfaces. Each weld pass or weld bead must penetrate the base metal and/or the previous weld beads that it touches. See Figure 12-19. A weave bead may be used for the fi nal weld pass. Exercise 12-2 Fillet Weld on a T-Joint in the Flat Welding Position 1. Obtain three 1/8″ (3.2 mm) diameter E6010 electrodes, six 1/8″ (3.2 mm) E6013 electrodes, and three 5/32″ (4.0 mm) iron powder electrodes, such as E6027. 2. Also obtain four pieces of carbon steel measuring 1/4″ × 2″ × 6″ (6.4 mm × 50 mm × 150 mm). GFEDCB A Goodheart-Willcox Publisher Figure 12-16. The effects of current, arc length, and travel speed on covered electrode beads. A—Correct current, arc length, and travel speed. B—Amperage too low. C—Amperage too high. D—Arc length too short. E—Arc length too long. F—Travel speed too slow. G— Travel speed too fast. Chapter 12 SMAW: Flat Welding Position 177 Copyright Goodheart-Willcox Co., Inc.

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Page 2Section 1 Introduction to Welding click to expand contents

Page 126Section 2 Shielded Metal Arc Welding click to expand contents

Page 208Section 3 Gas Metal and Flux Cored Arc Welding click to expand contents

Page 276Section 4 Gas Tungsten Arc Welding click to expand contents

Page 334Section 5 Plasma Arc Cutting click to expand contents

Page 350Section 6 Oxyfuel Gas Processes click to expand contents

Page 478Section 7 Resistance Welding click to expand contents

Page 504Section 8 Welding in Industry click to expand contents

Page 590Appendices click to expand contents

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