The Welding Of Nickel-base High Temperature Alloy Tube By HP40Nb And HP45NbTi

Pipeline is the important constituent part of petroleum chemical device, in this text ,emphasize to introduce the sort and characteristic of Nickel-based high-temperature alloy which applied in oil refining furnace tubes, and introduced its methods and crafts of welding. In the last, the welding ability of high-temperature alloy HP45NbTi and HP40Nb were analysed.The HP45NbTi and HP40Nb furnace tubes with thickness of 11mm 10mm and outer diameter of 125mm were butt-welded using a combined process. The HP40Nb root passes were welded by manual TIG with nickel based wire 20.70.Nb and HP45NbTi with NiR82. And the subsequent filling and top passes with wire 25-35NboThe microscopic structure of base metal HAZ fuse area and weld center with high-temperature alloy HP45NbTi and HP40Nb were observed. From the microscopic structure of postwelding, we found the structure became coarsing. In order to satisfy operating requirement, we should adopt the smaller weld heat input and avodi the HAZ, welded joint superheating. From the organization of the fusion area, we can see the organization transition good, and did not see the flaw, such as crack and pore...etc.and all this explain the welding quantity satisfies the request. But pass the observation ,we can discover that the columnar structure of weld center is condensation and small. On the grain boundary, flaw such as precipitated phase pore crack and slag spot.ect.were not found. The austenite structure is arborescent crystal distribute and carbide is in the center of arborescent crystal. From metallurgical structure ,we can discover the two kinds of projects are difference in HAZ fuse area and weld center .the weld structure with adopt welding wire 25-35Nb is bigger than 25-35Nb From the mechanical properties ,the main reason of welding performance became worse is the coarse structure. And analyzed the alteration of plastic property and ductility with base metal HAZ fusion area and weld zone. After welding,the degree of hardness with HAZ fusion area and weld zone are higher than the base metal. But plastic property and ductility arelower than base metal. Among them,the degree of hardness with weld center are max.Namely,the intensity of weld center is tiptop and the HAZ fusion area are gradually debase.But the plastic property and ductility of weld center are minimum, HAZ and fusion area are gradually elevation.From examined the mechanical properties of room and high temperature, the welded joint were up to the mustard. The welding producing efficiency is higher and the external appearance quantity is beautiful.