A Study On Single Layer Electroslag Surfacing-and-properties Of Surfacing Deposit For Hydrogenation Reactor

As an important energy source in economic production,oil is a non-renewable resource.Its storage capacity is declining,the quality of crude oil obtained by petrochemical enterprises is declining.In order to ensure the quality of petroleum products produced by inferior raw materials,petrochemical enterprises often use hydrogenation technology in the process of oil refining.Hydrogenation reactor is an important equipment in the process of oil hydrogenation refining,and used in high temperature,high pressure and hydrogen environment.Faced with a variety of corrosion problems,once Malfunction or accident happen in the equipment,catastrophic losses will be happened.Therefore,there is a high technical requirement for hydrogenation reactor manufacturing.Hyd rogenation reactor works in the environment of high temperature and high pressure,the Cr-Mo heat-resistant steel is used as the main material to ensure the strength.At the same time,the hydrogenation reactor is also exposed to a variety of corrosive med ia during operation,so,a certain thickness austenitic stainless steel corrosion resistance layer should be deposited on the inner wall.At present,the double layer surfacing technology of the transition layer and corrosion resistant layer is often used.But double deck surfacing is needed,which leads to low production efficiency and more waste of surfacing material.In order to overcome these shortcomings,in this paper,single layer electrode electroslag surfacing has been carried out by using the hydrogenation reactor material 12Cr2Mo1 R steel as the base material.On this basis,the high-speed electrode electroslag surfacing technology is studied in order to further improve welding efficiency and reduce production costs.Single pole electroslag surfacing test is carried out by using Sandvik welding strip 21.11.LNb and matched welding flux 47 S.Moreover,the specimens of welded and composition,microstructure and properties of surfacing layer of 690?×32h after stress annealing were analyzed.The results show that the chemical composition of surfacing layer is qualified,the mechanical properties,the content of ferrite,and the corrosion of sulfuric acid and copper sulfate were qualified for both welded and 32 hours after stress annealing.High-speed strip electrode electroslag surfacing layer test has been carried out with three kinds of welding materials provided by three companies--Tientai,Kobe Steel Group,WEL,and the specimens of welded and the properties of surfacing layer of 690?×32h after stress annealing were analyzed.The results show that the Cr content of the surfacing layer completed with TBD-309 LNb and flux ML-305 HS was low,and the ferrite content was not qualified 32 hours after stress annealing;The Cr content of the surfacing layer completed with ESS 309 Nbl and flux F-9NB welding is high,and the mechanical properties and ferrite content are not qualified 32 hours after stress annealing.The chemical of the surfacing layer only completed with US-B24.13.LNb and flux N-04178 is qualified,and the mechani cal properties,the content of ferrite,and the corrosion of sulfuric acid and copper sulfate hydrogen stripping test were qualified both for welded and 32 hours after stress annealing.In order to study the effect of heat treatment system on corrosion res istance of hardfacing layer of high speed electroslag surfacing,the microstructure,the number of ferrite,composition change near the line of fusion and electrochemical corrosion in Na Cl solution and 9.8% H2SO4 solution with mass fraction of were analyzed under different stress annealing.The test results show that the cladding layer is composed of austenite and a small amount of ferrite,also a few second phase particles;at the position close to the fusion line,the ferrite is mainly in the form of lath s hape,and at the position a little far from the fusion line,the ferriteis mainly in the form of skeleton;and the stress relieving annealing time has no obvious influence on the microstructure of the surfacing layer.With the increase of heat treatment time,the content of ferrite showed a decreasing trend.According to the line analysis of EDS,it is found that the element distribution near the fusion line is mainly caused by the dilution of the base metal to the surfacing layer during the welding process.El ement diffusion in the process of stress relieving annealing has little effect on the distribution of elements.High speed single layer electroslag surfacing technology improves the speed of surfacing,reduces welding heat input,refines the microstructure of the surfacing layer,and reduces intergranular corrosion and pitting susceptibility.The stress relieving annealing reduces the ferrite content of the surfacing layer and the intergranular corrosion resistance and pitting corrosion resistance of the surfacing layer were affected.The high-speed single layer electrode electroslag surfacing technology was applied to the hydrogenation reactor.Due to higher welding speed,only a layer of austenitic stainless steel can be welded to meet the technical requirements of the surfacing layer.Thereby,the production efficiency is greatly improved,the manufacturing cost is greatly reduced,and the utility model has good application prospect.