Machinery's Handbook, 31st Edition
Flux-Cored Arc Welding 1585 in weld transfer characteristics and recommended current, voltage, and other settings between electrodes made by different manufacturers. The chemistry and slag of the elec- trodes developed for welding in the flat and horizontal positions (E70T-X) typically pro - vide superior results when they are used for flat and horizontal applications where the surface conditions of the plate are suspect or large, deep-penetrating welds are required. All-position electrodes are intended for, and best used in, vertical and overhead welds. For extensive welding in flat or horizontal positions, the welder is better served with the electrodes designed for these specific positions. All-position, gas-shielded FCAW electrodes provide unique benefits and potential for cost savings. In contrast with short-circuit GMAW, or pulsed GMAW, the all-position FCAW electrodes used for vertical up welding of carbon, low-alloy, or stainless steels are simpler to operate, are capable of greater weld quality, and will provide two to three times the rate of weld deposition. The electrode most commonly used in the United States for vertical up welding on carbon steels is the type E71T-1. The equivalent to the E71T-1 standardized electrode specification now in use in other countries include: Canada, E4801T9; Germany, SGR1; and Japan, YFW 24. If the end user selects the correct all-position electrode diameter, the routine weaving of the electrode during vertical up and overhead applications may be minimized. Keeping the weld weave to a minimum reduces the skill level needed by the welder and increases the potential for consistent side-wall fusion and minimum porosity. If weaving is necessary, a straight-line oscillation technique is often preferred. Typical settings for welding with various sizes of gas-shielded FCAW electrodes are shown in Table 7. Table 7. Typical Settings for Welding with Gas-Shielded FCAW Electrodes Electrode Diameter Vertical Up Welds Flat and Horizontal Welds inch (mm) 0.035 (1) Feed rate
450 ipm (11.4 m/min) 165 amps 28 volts 350 ipm (8.9 m/min) 200 amps 25 volts 240 ipm (6.1 m/min) 200 amps 25 volts 210 ipm (5.3 m/min) 240 amps 25 volts
Feed rate Current Voltage Feed rate Current Voltage Feed rate Current Voltage Feed rate Current Voltage Feed rate Current Voltage
630 ipm (16.0 m/min) 250 amps 30 volts 560 ipm (14.2 m/min) 280 amps 26 Volts 520 ipm (13.2 m/min) 300 amps 30 volts 350 ipm (8.9 m/min) 340 amps 29 volts 210 ipm (5.3 m/min) 460 amps 32 volts
Current Voltage Feed rate Current Voltage Feed rate Current Voltage Feed rate Current Voltage
0.045
(1.2)
0.052
(1.4)
0.062
(1.6)
(2.4)
…
3 ∕
32
Material Condition and Weld Requirements.— Practical considerations for selecting a gas-shielded, flux-cored electrode depend on the material condition and weld require ments. FCAW electrodes are beneficial if the surface of the material to be welded is con taminated with mill scale, rust, oil, or paint; the fillet weld size is to be over 3 ∕ 8 in. (9.6 mm) wide (a GMAW single-pass fillet weld with an electrode size of 0.045 in. is typically 3 ∕ 8 in. wide); the weld is vertical up, or overhead; the required impact strengths and other mechanical properties are above normal levels; crack resistance needs to be high; and increased penetration is required. Selecting an FCAW Electrode.— Selection of FCAW electrodes is simplified by match ing the characteristics of flux-cored types with the material and weld requirements listed above. Once the correct electrode type is selected, the next step is to choose the optimum size. In selecting an all-position, flux-cored electrode for vertical up or overhead welding, the steel thickness is the prime consideration. Selecting the optimum electrode diameter allows the high current capability of the electrode to be fully used to attain maximum
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