Abstract: A method for gas tungsten arc welding (GTAW) of nickel-aluminide is provided. The method includes machining a weld groove having a width from 1 to 2 mm on an outer surface, a weld groove angle with a vertical being less than 30°; and a root face being not longer than 3 mm. During welding, a measured temperature 30 cm (12?) from a weld torch and 3 mm from the weld groove edge should not exceed 200° C.; and an interpass temperature should be less than 85° C. measured at 3 mm from the weld groove edge. With exception of the root pass, all filler and cap pass layering should start from the nickel-aluminide edge, each bead should be peened; and the weld cap pass should overlap on the nickel-aluminide surface edge by at least 3 mm. The weld bead layout at the nickel-aluminide edge should be laid at torch angle less than 30°, and the weld heat input should be in the range of 17 to 23 kJ/in. The linear welding speed is greater than 8.6 cm/min and a deposition rate should be greater than 3.0 cm3/min.

Abstract: Nickel-base radiant tube includes straight and curved elbow tube sections. The straight tube section has constant inner and outer radii. The elbow tube section has a constant inner radius and variable outer radius. The inner diameter of the elbow tube section is equal the inner radius of the straight tube section. Mating end portion of the elbow tube section has an outer radius equal to the outer radius of the straight tube section. Method for making the radiant tube comprises the steps of positioning a mating end portion of the straight tube section adjacent to and aligned with the mating end portion of the elbow tube section so that end faces of the straight and elbow tube sections face each other to define a circumferentially extending weld groove, and butt welding the mating end portions of the straight and elbow tube sections together at the weld groove.

Abstract: Nickel-base radiant tube includes straight and curved elbow tube sections. The straight tube section has constant inner and outer radii. The elbow tube section has a constant inner radius and variable outer radius. The inner diameter of the elbow tube section is equal the inner radius of the straight tube section. Mating end portion of the elbow tube section has an outer radius equal to the outer radius of the straight tube section. Method for making the radiant tube comprises the steps of positioning a mating end portion of the straight tube section adjacent to and aligned with the mating end portion of the elbow tube section so that end faces of the straight and elbow tube sections face each other to define a circumferentially extending weld groove, and butt welding the mating end portions of the straight and elbow tube sections together at the weld groove.

Abstract: Nickel-base radiant tube includes straight and curved elbow tube sections. The straight tube section has constant inner and outer radii. The elbow tube section has a constant inner radius and variable outer radius. The inner diameter of the elbow tube section is equal the inner radius of the straight tube section. Mating end portion of the elbow tube section has an outer radius equal to the outer radius of the straight tube section. Method for making the radiant tube comprises the steps of positioning a mating end portion of the straight tube section adjacent to and aligned with the mating end portion of the elbow tube section so that end faces of the straight and elbow tube sections face each other to define a circumferentially extending weld groove, and butt welding the mating end portions of the straight and elbow tube sections together at the weld groove.

Abstract: A method for gas tungsten arc welding (GTAW) of nickel-aluminide to itself or other nickel-based alloys using a filler wire. Method limitations: I) outer surface of weld groove has 1-2 mm machining, weld groove angle <30°; and root face <3 mm; II) measured temperature 30 cm (12?) from weld torch and 3 mm from groove edge <200° C.; and interpass temperature <85° C. at 3 mm from weld groove edge; III) except for root pass, all filler and cap pass layering should start from nickel-aluminide edge; each bead should be peened; and weld cap pass should overlap nickel-aluminide edge by 3 mm; IV) weld bead layout at the nickel-aluminide edge should be laid at torch angle <30°; V) weld heat input should be 17-23 kJ/in; and VI) linear welding speed is >8.6 cm/min; and deposition rate should be >3.0 cm3/min.

Abstract: Nickel-base radiant tube includes straight and curved elbow tube sections. The straight tube section has constant inner and outer radii. The elbow tube section has a constant inner radius and variable outer radius. The inner diameter of the elbow tube section is equal the inner radius of the straight tube section. Mating end portion of the elbow tube section has an outer radius equal to the outer radius of the straight tube section. Method for making the radiant tube comprises the steps of positioning a mating end portion of the straight tube section adjacent to and aligned with the mating end portion of the elbow tube section so that end faces of the straight and elbow tube sections face each other to define a circumferentially extending weld groove, and butt welding the mating end portions of the straight and elbow tube sections together at the weld groove.