TUBE AS 1283908 - Caterpillar

Heat input influences the cooling rate, and it is the cooling rate which significantly alters the mechanical properties of the weld metal and the heat affected zone. The properties most sensitive to adjustment in heat input are weld metal toughness and yield strength as indicated in the graphs below. Dual Shield II electrodes are formulated for optimum performance with heat inputs of 40 to 70 kilojoules per inch. A heat input of 55 kilojoules produces very good results in the vertical-up position.A means of calculating travel speed within a range of kilojoules is illustrated below. To use the chart, first select the desired amperage and voltage for your application. Next, multiply the amperage times 1,000 and locate this point on the vertical axis. A horizontal line drawn from this point will intersect the three heat input lines. Now, draw vertical lines from these intersections down to the travel speed axis. These points represent the best range of travel speeds to use.It should be noted that cooling rates are also influenced by plate thickness, joint design, preheat, interpass, temperature and number of passes. These additional factors should be taken into consideration when running procedure tests, since they will influence mechanical properties. Trouble Shooting
Consistently good welds throughout a wide range of welding conditions are easily obtained when the variables that affect the flux-cored process are understood and controlled. Each variable listed below is important in obtaining a balanced welding condition. Welding VoltageWelding CurrentWelding Travel RateWelding Gun AngleContact Tip to Work DistanceWhen any of these variables is out of adjustment, certain problems may arise. To obtain the best results in correcting these problems, the following suggestions are made:1. Electrode stubs on work. a. Voltage too low.b. Wire feed too fast.c. Poor ground.2. Arc burns back to contact tip. a. Voltage too high.b. Wire feed speed too low.c. Lose or worn feed rolls.d. Kinked or clogged welding conduit.3. Rough arc or heavy spatter. a. Improper volt or amps.b. Loose or worn contact tip.c. Arc blow.d. Gun pointing in wrong direction or too much angle in relation to the weld.e. Nozzle too far from the work.4. Erratic wire feed. a. Worn or loose contact tip.b. Worn feed rolls.c. Clogged welding conduit.d. Fluctuation of line voltage.e. Faulty relay or contactor in control.5. Weld bead is not uniform. a. Wrong volt/amperage setting.b. Inconsistent travel speed.c. Operator varying nozzle to work distance.6. Weld is undercut. a. Voltage too high.b. Excessive amperage for plate thickness.c. Excessive travel speed.d. Wrong gun angle.7. Weld metal porosity. a. Insufficient gas flow.b. Moisture in gas.c. Loss of gas due to wind or air currents.d. Excessive gas causing turbulence.e. Nozzle held too far from work surface.f. Contaminant on surface of plate.g. Wrong volt/amperage setting.8. Weld metal cracks. a. Wrong electrode for base metal.b. Preheat required and not being used.c. Stress cracks due to improper procedure. Welds should be welded from center out or toward an open end.d. Too much heat input (quenched and tempered steels).e. Chemistry of the base metal is