Research On Basic Processing Technology Of Wire Arc Additive Manufacturing Using 2.25Cr-1Mo-0.25V Steel In Hydrogenation Reactors

Mainly used in the process of hydrocracking,hydrorefining and catalytic reforming of heavy oil in petroleum refining,Hydrogenation reactor is a major key equipment of modern oil refining industry.There are disadvantages when fabricating hydrogenation reactors through traditional processes,such as long cycle and low material utilization.Arc Wire Additive Manufacturing is a kind of metal additive technology,which not only has high molding efficiency but also low cost,and is especially suitable for the manufacture of large composite metal components.In this paper,the cold metal transition technology is used,with the hydrogenation reactor using 2.25Cr-1Mo-0.25 V as the base material and a solid alloy welding wire as the filler material.The microstructure,as well as the change of the forming size and mechanical properties under different process parameters are studied.The effect of the simulated minimum post-weld heat treatment on the mechanical properties of the formed components is also investigated.The size and macroscopic morphology of components are directly affected by process parameters.A larger linear energy density will make a wider and higher weld in a singlelayer single-pass cladding process,but a moderate linear energy density is beneficial to reduce the surface waviness during multi-layer single-pass molding.When the welding speed is at a high level,a necking phenomenon will occur between the arcing section and the stable section.The width,depth and area of the heat affected zone increase with the increasing of the linear energy density,but the average size of austenite grain is less affected by the process parameters,mostly between 24?m and 29?m.During thermal cycling,the decomposition of M-A islands and the precipitation of carbides will occur inside the heat-affected zone.The test results of mechanical properties show that the presence of HAZ will degrade the mechanical properties of the joints of components.The mechanical properties of the horizontal direction of the additive component(horizontal direction: parallel to the scanning direction;vertical direction: parallel to the deposition direction)are related to the location.And there is a significant difference in the transverse and longitudinal mechanical properties,especially the plasticity.As the line energy density increases,the elongation difference between the horizontal and vertical directions will decrease from 45.1% to about 10%.The simulated minimum post-weld heat treatment will reduce the tensile strength of the deposited component,but it can effectively improve the plasticity deteriorated by the presence of the heat affected zone.The elongation can be more than doubled.The simulated minimum post-weld heat treatment can also significantly reduce the hardness of the heat affected zone and the welding metal so that the hardness distribution of each region tends to be consistent.