The Research Of Weld Cladding Of Inconel 625 On The Surface Of X 65 Steel By Hot Wire P-TIG Welding

With the growing global demand for fuels, more and more acid oil fields have been exploited. The severe environment calls higher request on the corrosion resistance of the pipeline used in the exploration of this kind of oil field, leading to the creation of the clad pipe. It combines the excellent mechanical properties of the pipeline steel with the excellent corrosion resistance of the corrosion resistant alloy. Besides, the production cost is relatively low. There are many types of clad pipe manufacturing method. Weld cladding can lead the base pipe and the lining to a metallurgical combination. Thus the interface bonding strength can be very high. Besides, the method can be operated flexibly. So it has a good application prospect. In this paper, the hot wire P-TIG was used to clad Inconel 625 on the surface of X 65 steel. The weld forming regularity based on welding parameters in the transverse welding process was investigated. And the characterization of Inconel 625 cladding was studied. All the above can provide theoretical basis for the manufacturing of clad pipelines.Firstly, the influencing factors except the welding input in the transverse welding forming were qualitatively analyzed, including the way and position of wire feeding, the angle of welding torch, the shape of tungsten electrode tip, the gas protection, the overlapping and so on.Secondly, the paper established the mathematical models based on the response surface methodology between the welding parameters and the forming parameters during the process of single-layer cladding at the horizontal position. The influential laws of various parameters on the forming parameters were analyzed. Results show that the welding current has a remarkable effect on each forming parameter. The increase of welding current will lead to the increase of weld width, the angle of inclination and dilution, as a result of which the reinforcement decreases. Moreover, the hot-wire current plays a significant role in the rate of dilution. The increase of it will result in a notable rise of the rate of dilution, and a slight increase of the angle of inclination and the reinforcement, but little changes of the weld width. The reinforcement, weld width and the angle of inclination decrease with the increase of the welding speed, but dilution changes slightly. Increasing wire feed rate will significantly increase the reinforcement, but decrease the angle of inclination and the rate of dilution, and has no remarkable impact on the weld width. The paper proposes an approximate calculation of the dilution by means of theoretical derivation. The results of the changing trend of the forming parameters are consistent with the experimental results.Finally, the microstructural and mechanical characterizations of Inconel 625 cladding and the influence of the welding current on the microstructure and property of the cladding were studied. The results show that there are several discontinuous partially-mixed zones(PMZ)and bright planar band at the bottom of the cladding. The increasing of weld current will reduce the area of PMZ and increase the width of planar. There are fewer precipitates at the bottom and top part than the middle part. The precipitates are mainly granular MC when the weld current is lower. When the current is higher, the precipitates are mainly irregular Laves phase. There is no harden region on the side of the cladding. The increasing of the weld current will slightly decrease the hardness of the cladding.