Laser Weiding Technology Of Ceramic Lined Composite Steel Pipe Based An Selfpropagating High Temperature Synthesis Technique

Submarine pipeline as the main part of offshore oil and gas field exploitation and production system, It is the fastest and most reliable, security and economic mode of transport large amounts of oil and gas continuously. Due to the oil and gas contains a lot of corrosion media such as H2 S, CO₂ and Cl-, the Al2O3 ceramic-lined composite steel pipe based on self-propagating high-temperature synthesis?SHS? technology possess both the advantages of the two materials of ceramic and steel, has a great application prospect in oil and gas pipeline. In this paper the experiment of laser weld ceramic-lined composite steel pipe which based on self-propagating high-temperature synthesis?SHS? technology with 5mm thickness Al2O3 ceramics and 15 mm thickness 45# steel outer layer has been investigated, which could offer data reference for joint technology of ceramic-lined composite steel pipe, through detection of the lining layer of composite pipe, the lining is not pure Al2O3 ceramic phase, contains a lot of metal oxide, and density of lined ceramic is insufficient, diffuse points inside the hole, all increase the welding feasibility of lining ceramic layer.The welding technology of ceramic-lined composite pipe include: first along the ceramic layer top edge upward to open 45 ° 60 ° V groove, using 3000 W CO₂ laser fusion welding ceramic layer of composite pipe, before welding ceramic layer of composite pipe, remove the inner ceramic layer to make ceramic chip, explore the fusion welding of ceramic chip, provides some references for the fusion welding of the ceramic layer of composite steel pipe. The fusion welding of ceramic chip mainly research matching relation between laser power P and welding speed Vs, regularly change laser power and welding speed, using an asana microscope to observe weld appearance, using scanning electron microscope?SEM? analysis the internal structure of weld, the results show that under the process parameters or laser power 700-1000 W, welding speed 800-1200mm/min, 30 L/min He gas shielding gas, are able to form good weld line, the weld organization is extended long and thin strip organization from both sides to middle, distribution of the dark grey and light grey facies in weld zone are more uniform. Design three kinds of Ni- Cr-Mo self-fluxing corrosion resistant alloy powder and one kind of Fe-Cr-Ni self-fluxing corrosion resistant alloy powder, fill pipe groove by laser cladding, further enhance the weld corrosion resistance and achieve the pipe's strength connection, before the groove filling, make cladding layer on 45# steel with the same process parameters. respectively according to the regulations of American standard ASTM G48 test method, test conditions, and the actual working condition of a domestic oil fields of simulated CO₂ / H2 S environment to determine the corrosion resistance of cladding layer and compare with strong corrosion resistant 316 L stainless steel, the results prove that corrosion resistance of cladding layer made by Ni –Cr-Mo powder with Ingredients?Cr 15wt%, Mo 5wt%, Fe 9wt%, B 2.5wt%, Si 1.5wt%, Ni allowance? is best, corrosion resistance of cladding layer made by Fe-CrNi powder with Ingredients?Cr 20wt%, Ni 10wt%, B 2.5wt%, Si 1.5wt%, Fe allowance? is better than 316 L stainless steel. According to the result of ceramic chip fusion welding research and combining the actual situation of the composite pipe welding, designate fusion welding process parameters of ceramic layer of the composite pipe : laser power 1000 W, welding speed 1200mm/min, 30 L/min He gas shielding gas, and respectively use Ni-Cr-Mo powder with Ingredients?Cr 15wt%, Mo 5wt%, Fe 9wt%, B 2.5wt%, Si 1.5wt%, Ni allowance?, Fe-Cr-Ni powder with ingredients?Cr 20wt%, Ni 10wt%, B 2.5wt%, Si 1.5wt%, Fe allowance? fill the groove of composite pipe, further enhance the weld corrosion resistance and achieve the pipe's strength connection, In order to prevent the weld area and 45 # steel forming primary battery by different chemical components, accelerate steel pipe outer surface corrosion, design a kind of Fe base alloy powder similar to 45# steel's chemical composition called Fe-45#, cut steel pipe, observe the morphology of back of weld line, the results prove that there is an obvious ladle bulge on the back of the ceramic weld line, ceramic layer implements the fusion welding, there is no defects such as cracks, porosity in packed layer, and good metallurgical bonding with steel tube formation, and implement good metallurgical bonding with steel tube, Between cladding layer and ceramic weld is tight physical connection.