Welding duplex alloys is not particularly difficult, but the heat input and interpass temperature must be controlled to maintain the ferrite-austenite balance. Otherwise, the advantages of using the duplex material will be sacrificed. The time spent at 1,300 degrees F to 1,800 degrees F must be controlled. The heat-affected zone (HAZ) time-at-temperature is critical in controlling the intermetallic phases. If the matching filler wires or electrodes (ER2209 or E2209) are used to join the material, there is a slight disadvantage versus using the more expensive ERNiCrMo-3 or ENiCrMo-3 welding materials in the area of crevice corrosion. The nickel content of E2209 and ER2209 is in the range of only 7 percent to 9 percent, while the nickel content of ERNiCrMo-3 and ENiCrMo-3 is 56 percent to 58 percent. The addition of columbium and niobium limits the carbide precipitation in the HAZ. This cost is worthwhile, but it slightly diminishes the duplex's cost advantage. Another disadvantage is in the rolling and bending process. Duplex's tensile and yield strength and the work-hardening tendency cause springback and sometimes re-forming. This is not always the case, but is common in materials thicker than 3/4 in. There are advantages and disadvantages with all materials, as well as specific methods to overcome the disadvantages. Overall, the advantages of duplex materials make themna great addition to the ever-growing compilation of materials. Using these alloys in the power generation field has proven to be valuable for the scrubber fabrication. | 