917 results about "Submerged arc welding" patented technology

The automatic argon arc welding and narrow gas submerged arc welding process for circular pipe header seam features the first horizontal and vertical welding with immobile workpiece and using automatic cold welding TIG wire until completing over one third of circle; the subsequent welding in the other two thirds of circle with automatically rotating welding roller frame; and the performing in the identical site of the annular seam assembling and the welding. The welding apparatus for the said technological process consists of roller device and welding frame bogie, and the welding frame bogie on some tracks parallel to roller frame tracks is movable. The present invention has the advantages of automatic operation, raised welding quality, etc.

The invention belongs to the field of welding, in particular to a process method applicable to marine engineering large thick steel plate submerged arc welding in low-temperature environment, which comprises a welding method, welding material selection, a welding order, a welding process and the selection and control of various welding process parameters. The method renders with carbon dioxide gas protection welding, and fills and faces through an automatic submerged arc welding; stops welding when the welding reaches more than two thirds of the thickness of a large groove during the welding process, clears chips on the back side and completes the welding of the other side; finally completes the welding of the first side; strictly controls all relevant process parameters of the welding during the welding process, and solves the problems of poorer anti-crack toughness of welding seams and heat affected zones caused by too high cooling speed of the welding seams and too high temperature; can ensure good anti-crack toughness of a welding seam connector without heat treatment after welding; and can meet the requirements of welding of an E36 plate with the thickness of 35 to 77mm under the working environment at the temperature of above -30DEG C, simplifies the production process, shortens the production cycle and reduces the cost.

The invention discloses a girth welding technology for a vacuum container, which comprises the following steps: processing beveled edges, assembling and welding. In the step of processing the beveled edges, a 14mm thick 0Cr18Ni9 austenitic stainless steel material is selected as a cylinder base material, X-shaped beveled edges are adopted, an inside beveled edge is processed for 10mm with a single-side angle of 32.5 degrees, an outside beveled edge is processed for 4mm with a single-side angle of 35 degrees, and no truncated edge is left. In the step of assembling, reserved clearances of 2.0-2.5mm are assembled, argon tungsten-arc welding is adopted to position, a positioning welding length is 10-15mm, an interval is 200mm, and then a 'strut having a shape of Chinese character 'mi' which is used for adjusting the roundness of a cylinder is welded in the cylinder. In the step of welding, an argon arc welding double-gun butt-welding method is used for bottoming the interior of the cylinder, two layers are filled in an inner welding bead of the cylinder in the manner of manual arc welding, an external welding bead is covered in the manner of submerged-arc welding, and finally, the inner welding bead is covered in the manner of manual arc welding. The girth welding technology can be used for controlling the welding deformation and has the advantages that the method is simple and is easy to realize.

The self-protective high chromium cast iron cored build-up welding wire has metal powder core comprising nickel powder 6-8 wt%, middle carbon manganese iron 8-10 wt%, No. 45 ferrosilicon 9-12 wt%, high carbon ferrochromium 65-75 wt%, metal Cr powder 18-21 wt%, ferromolybdenum 5-7 wt% and Al-Mg powder 1.5-2.5 wt%, and with one welding wire filling amount of 0.49-0.53. The present invention makes it possible to use the welding wire in submerged arc welding without needing added flux and protecting gas, results in raised comprehensive welding performance and raised welding quality, and may be applied widely in build-up welding field requiring high antiwear, anticorrosive and anticracking performance.

The present invention relates to the high intensity pipeline steel burying arc solder. It solutes the question that because of the Cu's deposition, it leads to separate out Cu easily and ossify the steel in the smelting and the disposal of the heat and contains too many microelements so that it has disbennifits to the smelting technical control. The technical steps are that the weight percent of the chymic component is C 0.04~0.12,Si 0.005~0.10,Mn 1.20~2.00,Ni 0.10~0.60,Cr 0.10~0.60,Mo 0.10~0.50,Ti 0.04~0.15,B 0.002~0.012,P<=0.015,S<=0.01, and the allowance is Fe. The invention solders matchingly with the alkalescence sinter flux. The resist drawing intensity of the welding line is higher than 650MPa.The intensity of the welding line of the jointing X80 pipe line steel reaches 740MPa, and the -20 Deg. C concussion power is higher than 120J.Then the content of the welding line S and P is low and the degree of purity is high. It applies to the burying arc jointing of the X80 high intensity pipeline steel and the other corresponding intensity low levels' alloy which resisted drawing intensity is between 620 and 740MPa.

The invention relates to a butt joint submerged-arc welding method of bridge steel with tensile strength more than 690Mpa grade, overcoming the defects that at the present, bridge steel and other engineering structural steel which are in 690Mpa strength grade needs preheating before welding and heat treatment after welding and has severe welding environment and the like during manual and gas protective welding. The butt joint submerged-arc welding method comprises the following steps: adopting steel with tensile strength Rm of between 690Mpa and 745Mpa, the yield strength ReL of between 550 and 690Mpa, the extension rate A of between 19 percent and 21 percent, KV2 ballistic work of between 165J and 180J at 40 DEG C below zero and the thickness of 40mmm, and adopting same-thickness butting;adopting matched welding wires with the tensile strength more than 690Mpa and diameter phi of 4.0mm, and using CHF105 as a welding flux; adopting a double-sided X-type asymmetrical submerged-arc welding groove with the angle of 60 degrees and the truncated edge of 5mm; continuously welding until welding seams are full, and under the conditions that the welding current is 570A, the voltage is 31V,the speed is 35cm/min and the linear energy is 30kj/cm; baking the welding flux for 1 hour at 350DEG C and keeping the temperature of welding layers between 100 DEG C and 150DEG C.

The invention discloses a welding method for Q345qDNH weather-resisting steel for a bridge. According to the welding method provided by the invention, specific to the special chemical components, suitable technical conditions and different slab thickness of the Q345qDNH weather-resisting steel for the bridge, a welded joint is jointed in a butt-jointed or T-shaped corner jointed form. According to the welding method, submerged-arc welding, drug core CO2 gas shielding semi-automatic welding or shielded metal arc welding is adopted and the weld preheating temperature is confirmed according to the different slab thickness. According to the welding method provided by the invention, the joint form and the thickness size of a bridge structure are completely covered; the technical scheme is simple and the applicability is strong; the implementing effect meets the technical demands of the present related standard for the construction of the bridge steel and the bridge structure; and the welding method can be practically applied to the welding of the Q345qDNH weather-resisting steel bridge structure.

A method for manufacturing double metal composite wear-resistant metallurgical rollers includes steps of roller core processing, preheating, surfacing of a composite layer, finish machining and thermal treatment. The roller core processing step includes subjecting steel good in tensile strength, yield strength and impact resistance to forging, pressing and tempering, manufacturing roller core blanks, subjecting the roller core blanks to rough machining to reserve size for a surfaced composite layer. The preheating step includes preheating the roller cores to the optimum surfacing temperature of 380 DEG C +/- 5 DEG C. The surfacing step of the composite layer includes surfacing and filling the reserved surfaced composite layer by flux-cored wires on the surface of the preheated roller cores by means of submerged-arc welding process. The finish machining step includes processing the surfaced double metal composite wear-resistant metallurgical roller blanks into design size. The thermal treatment step includes quenching and tempering the double metal composite wear-resistant metallurgical rollers subjected to finish machining, so that the surfaces of the double metal composite wear-resistant metallurgical rollers can meet the requirements for good anti-sticking abrasion, grain abrading resistance, red hardness, resistance to cold and hot fatigue, and peeling resistance.

The invention discloses a submerged arc welding method of plank boards and jointing boards, which is characterized in that through steps of reasonable welding material selection, strict pre-welding preparation, scientific pre-welding preheating, welding process and welding technology, the welding quality of submerged arc automatic welding of plank boards with the thickness of 25mm to 45mm is controlled. The pass rate of welding seams by shooting once reaches 100 percent, and welding distortion is controlled ideally. The mechanical property of a welding joint meets standard requirements, and ensures the quality of products.

The invention discloses a longitudinal seam red copper liner welding process of a steel sheet pressure vessel. The longitudinal seam red copper liner welding process sequentially comprises the steps of (a), aligning and splicing a longitudinal seam of a machined cylinder and carrying out point welding fixation; (b), placing the inner longitudinal seam of the machined cylinder on a red copper liner; (c), aligning the longitudinal seam of the machined cylinder to the center line of a welding groove of the red copper liner, fixing the machined cylinder and the red copper liner through an air cylinder, and guiding water into a cooling water pipe of the red copper liner; (d), carrying out welding; (e), disassembling the machined cylinder after the longitudinal seam of the machined cylinder is welded. The welding process has the advantages that automatic submerged arc welding of one-side welding and two-side forming is achieved, the RT flaw detection qualification rate is high, welding flux is saved, the manufacturing quality of the steel sheet pressure vessel is improved, and the production cost is lowered.

The invention provides a method for welding Q500qE ultralow-carbon bainite steel for a bridge. The method is excellent in joint mechanical performance and high in welding efficiency and specifically includes that aiming at specific chemical components, applicable technical conditions and different plate thicknesses of the Q500qE ultralow-carbon bainite steel for the bridge, preheating temperature before welding, groove types and welding process parameters are determined; a welding joint type adopts butt joint, penetration angle joint or ship position T-shaped angle joint; a welding method adopts submerged arc welding, CO2 gas shielded semiautomatic welding or shielded metal arc welding. By the welding method, the joint type and thickness specifications of a bridge structure are comprehensively covered, the technical scheme is simple, convenient and high in adaptivity, all implementing effects meet technical requirements of standards related to building of bridge steel and the bridge structure, and the method is of great significance in promoting upgrading of the bridge steel and development of large-span steel bridge building technology. The method can be applied to building of the bridge structure, can also be applied to welding of other ultrathin-carbon bainite steel and is high in adaptivity.

The invention relates to the technical field of welding of H-shaped steel and particularly relates to a back-chipping-free full-penetration submerged-arc welding process method for welding H-shaped steel with a web plate more than 16mm thick. The process method comprises the steps of material selection, edge preparation, assemblage of the H-shaped steel, positioned welding, preparation before welding, welding and the like, wherein the assemblage is required to be zero assembling, and an assembling interval is less than or equal to 0.5mm; the angles of K-shaped symmetrical beveled edges are designed to be at 60+/-2 degrees, and the truncated edges of the beveled edges range from 1mm to 2mm; and the standard lengths of copper cushion blocks are designed to be 530mm and 130mm. The submerged-arc welding process method has the advantages of low cost, high efficiency, labor saving, reduction in environmental pollution and the like; and according to primary measurement and calculation, the welding process method can reduce the cost for welding the H-shaped steel with the web plate more than 16mm thick by 25%.

The invention discloses a technology for repairing surfacing of a piston rod of a super large marine diesel engine, and the technology can carry out the deep repair of the surface of the piston rod. The adopted surfacing process is as follows: flaw detection and straightening are carried out on the piston rod, turning machining is carried out on the surface of the piston rod to remove a defect layer, and individual deeper cracks are manually removed by grinding; fire whirl is used for heating the piston rod twice, the first heating is carried out till 200 DEG C-250 DEG C, the heating is stopped, the race rotation is carried out for 30 minutes, the second heating is further carried out after the temperature difference between the interior and the exterior is reduced, and a surfacing machine tool is rotated after reaching 250 DEG C-300 DEG C; submerged arc welding is used for rotating dual heads of the surfacing machine tool and a 2Cr13 flux-cored welding wire for carrying out the simultaneous surfacing, and asbestos cloth is used for wrapping and keeping the temperature during the welding process; the piston rod wrapped by the asbestos cloth for slow cooling after the surfacing achieves the size requirement, when the temperature is decreased to be lower than 100 DEG C, the piston rod wrapped by the asbestos cloth is vertically placed till the temperature is decreased to the room temperature, and then the temperature-keeping cloth is removed. The surface of the piston rod after the repair by employing the method has no weld defects, the piston rod fully meets the performance requirements, and the cost is only about one fifth of the cost for fabricating a new piston rod.

The invention discloses a method for manufacturing X70 steel-level large deformation-resistant longitudinally submerged arc welding pipes, which is applied to the manufacture of special welding pipes for oil and gas transmission. In the method, a controllable rolled steel plate is used, wherein the controllable rolled steel plate has a ferrite-bainite double-phase metallurgical microstructure and contains the following chemical components: 0.04 to 0.07 percent of C, 1.60 to 1.85 percent of Mn, 0.15 to 0.30 percent of Si, not more than 0.003 percent of S, not more than 0.010 percent of P, 0.15 to 0.30 percent of Ni, not more than 0.020 percent of Ti, 0.015 to 0.040 percent of Al, 0.010 to 0.065 percent of Nb, not more than 0.006 percent of N, not more than 0.30 percent of Cu, 0.10 to 0.25 percent of Cr, and not more than 0.0005 percent of B. The method comprises the following steps: (1) milling edges of the steel plate; (2) pre-bending bended edges; (3) performing JCO forming; (4) pre-welding joint seams; and (5) performing finish-welding on the inner and the outer sides of the joint seams. The method is applied to the manufacture of large-deformation-resistant welding pipes which are used in seismic belts, frozen soil areas, landslide area and other areas with high risk of deformation. The method has the advantages as follows: in the JCO forming process, the local deformation amounts and straight edge sizes of the steel plate in different rolling passes are analytically acquired according to the width, thickness and strength of the steel plate and the size of a die so as to determine the rolling passes and ensure uniform deformation at all parts of the steel plate after forming; and in the diameter expansion process, the minimum diameter expansion amount is determined according to the size and shape of the formed steel pipe, so as to ensure the size, shape and physiochemical properties of the steel pipe after diameter expansion.

The invention relates to a super-thick steel plate welding method. According to the method, the fabrication weldability of super-thick steel can be effectively improved, and the construction efficiency and the weld inspection first-pass yield can be improved. The method comprises the following steps of 1, processing a welding groove; 2, preparing before welding; 3, preheating before welding; 4, welding. The method is simple; the improved design of the welding groove is reasonable and reliable, and the method is suitable for common domestic single wire submerged arc welding machines and is high in practicability; a combined welding process of taking super low hydrogen electrode arc welding as backing weld and adopting submerged arc welding for filling and cosmetic welding is adopted, and the welding advantages of the two processes are integrated; the fabrication weldability of the super-thick steel plate is greatly improved, the welding quality of the super-thick steel plate is controlled, the first-pass yield of super-thick steel plate butt weld inspection is improved, and the method can be widely applied to welding construction of low-alloy high-strength structural steel super-thick steel plates which are 60-300mm in thickness and has good technical, economic and social benefits.

The invention discloses a deposition forming manufacturing method of parts and molds, and belongs to the field of non-mold growing manufacturing and remanufacturing. The method comprises the following steps that S1, the three-dimensional CAD model of a workpiece to be formed is subjected to hierarchical slicing; S2, the CNC codes of all hierarchical slices are acquired; S3, deposition forming is conducted layer by layer according to the CNC codes of all the hierarchical slices, the fine portions of the workpiece are formed by laser, and one or more technologies in electric arc welding, electron beam welding, electroslag welding and submerged-arc welding is or are adopted to form the thick wall and the non-fine portions of the workpiece; or in the S3, a heat source which is compounded by laser beams and gas protection electric arcs or a heat source which is compounded by the laser beams and vacuum protection electronic beams is adopted for forming the thin wall and the fine portions of the workpiece, and the gas protection electric arcs or the vacuum protection electron beams are shut down. According to the deposition forming manufacturing method, direct deposition forming can be achieved to obtain parts and molds which are stable in structure property and high in manufacturing precision and are provided with thin walls or fine portions.

The invention discloses a submerged-arc welding process of a stainless steel composite steel plate, which has the advantages that the labour intensity of welders can be effectively reduced, the labour condition, production efficiency and the welding quality are improved, the production cost is reduced, and the like. The invention comprises the following processes of: (1) processing a groove, i.e., processing the welding end of the stainless steel composite steel plate to be welded into a groove; (2) using the weld bead in the middle part of the groove as a bottoming weld line, using the weld bead at the upper part of the base layer bottoming weld line close to the stainless steel composite steel plate composite layer as the multicoat weld line and using the weld bead at the lower part of the base layer bottoming weld line as the base layer filling cap weld; (3) welding the base layer bottoming weld line by a traditional process; (4) welding the base layer filling cap weld by a traditional process; and (5) welding the multicoat weld line, wherein the welding current ranges from 350A to 400A, the welding voltage ranges from 28V to 30V and the welding speed ranges from 40cm/min to 50cm/min.

The invention discloses a welding method of a stainless steel clad plate, and relates to the technical field of welding. The welding method comprises the following steps that surface oxygen complexes of the stainless steel clad plate are removed; a groove is machined, the groove is an X-shaped groove, the angle of the groove is 55-65 degrees, the root gap of the groove is 1-3 millimeters, and the root portion of a joint is placed in a base layer; a base layer is welded, a first welding layer and a third welding layer of a welding seam of the base layer are welded in a submerged automatic arc welding mode, the third welding layer is provided with a plurality of welding beads, and a second welding layer is welded in a gas metal arc welding mode; a transitional layer on the connecting portion of the base layer and a multiple layer is welded, a fourth welding layer and a fifth welding layer of the transitional layer are both welded in the gas metal arc welding layer; the multiple layer is welded, a welding seam of the multiple layer is a sixth welding layer, and the sixth welding layer is welded in a large-current submerged-arc welding mode. Compared with the prior art, the welding method of the stainless steel clad plate improves the quality of a welding joint of the stainless steel clad plate and is high in welding efficiency.

The invention discloses a submerged arc-welding method of thick steel slab for large pressure vessel with tensile strength of 610-670 MPa, which solves the currently existing defects that the impact energy of deposited metal and the actual joint tenacity can not meet the welding requirements for the production of large high-strength thick steel slab structure. A measure adopted by the invention is as follows: the method comprises the following steps of: adopting pressure vessel steel with tensile strength of 610-760 MPa and thickness of 44mm to 55mm; using matched welding materials: the tensile strength of a welding wire is 610-670 MPa with diameter of 4.0mm and welding flux SJ105Q is adopted; adopting an unsymmetrical double-side V-shaped groove with an angle of 60 degrees as the groove of submerged arc-welding and a blunted edge of 4mm; continuously welding at the butt joint till weld seams are filled up under the conditions of 700A welding current, 36V voltage, 30cm/min speed and 50kJ/cm energy input; using a welding flux roasting system of 350 DEG C multiplied by 1h; and adopting interlayer temperature of 100 DEG C to 150 DEG C. In the invention, preheating is not required before welding and heat treatment is not needed after welding and joints have good low temperature impact toughness and safety storage.

The invention discloses a determination method for heat source model parameters in multiplewire submerged-arc welding by numerical simulation. The determination method comprises the following steps of: determining a heat-flow density distribution function in the multiplewire submerged-arc welding process; initially determining the heat source model parameters, wherein the heat source model parameters to be determined includes Ui, Ii, v, n, taui, etai, alphai, f<fi>, bi, ci, a<fi>, and a<bi>; and finally determining a heat-source model, wherein the determined parameters are substituted into the heat-flow density distribution function q(x, y, z, t) which is then taken as a thermology boundary condition for repeated iterative computations by a numerical simulation tool, the computation result of iterative computation of each time is compared with the shape of a joint fusion pool obtained by actual welding, the heat-source model parameters bi, ci, a<fi>, a<bi> are gradually adjusted by a range of 5% according to the comparison results until the errors between the parameters of the fusion depth and the fusion width of a simulated fusion pool and the fusion depth and the fusion width of the actual joint fusion pool are smaller than 10%, and then the determination of the heat-source model parameters in the multiplewire submerged-arc welding is finished.

A submerged arc welding flux material for X80 pipeline steel comprises the following components according to weight percentage: 15 percent to 25 percent of CaF2, 15 percent to 30 percent of MgO, 10 percent to 14 percent of Al2O3, 5 percent to 10 percent of CaSiO3, 5 percent to 9 percent of SiO2, 5 percent to 10 percent of MnO, 5 percent to 10 percent of TiO2, 1.0 percent to 2.5 percent of Na2O, 1.5 percent to 3.0 percent of B2O3, 0.2 percent to 0.4 percent of Re(Mg) and 6 percent to 10 percent of ZrO2, wherein the weight percentage of CaSiO3 plus SiO2 is less than or equal to 15 percent of the total weight of all the components, and the residual is mineral powder impurity. When being matched with alkali sintered flux for use, the welding flux material that is obtained by adopting a sintering method has the properties of strong weld seam strength, better H2S stress corrosion resistance and better low-temperature flexibility, the weld seam strength and the flexibility can be matched with substrate of high-grade pipeline steel, and the material is suitable for welding pipeline steel with the strength level ReL of more than or equal to 555 MPa and above and other structural steel.

The invention discloses a double-arc four-wire automatic submerged arc welding machine and the manufacturing method thereof. The automatic submerged arc welding machine include a welding power supply, an upright post which is arranged on a trolley and a running gear and is provided with a top part with a lifting mechanism, a cross arm which is movably connected with the lifting mechanism and can move up and down along the upright post, a welding head which is equipped with a welding gun and a solder hopper, a wire guide arranged between the welding gun and a welding wire spool, a wire feeding device, a swing mechanism which is arranged on the trolley and is used for control the upright post to rotate relatively to the trolley, and an electric control cabinet which is fixed on the upright post. Compared with the prior art, the double-arc four-wire automatic submerged arc welding machine of the invention has the advantages as follows: the structure is novel, the arrangement is reasonable; the process engineering parameters such as power efficiency and so on are improved for satisfying technological requirements of welding a gas steam turbine; the welding efficiency can be increases by at least three times; a machine head, an operator seat lifting arm, a corner, a falling protector and other devices are arranged; the solder can be automatically reclaimed and fed, and applied continuously, thereby reducing labor intensity, improving operational environment and conducing to operation.

The invention belongs to the field of material science and engineering and relates to a special flux-cored wire for carrying out preheating-free and heat treatment-free surfacing repair and reproducing on shaft and gear parts. The special flux-cored wire comprises the following chemical compositions in percentage by weight: 5 to 10 percent of fluorite, 20 to 40 percent of high-carbon ferrochrome, 5 to 10 percent of high carbon ferromanganese, 5 to 10 percent of ferrosilicon, 5 to 10 percent of ferromolybdenum, 10 to 15 percent of rare earth oxide, 15 to 20 percent of metallic nickel, 2 to 5 percent of ferrovanadium, 2 to 5 percent of ferrocolumbium, 2 to 5 percent of ferrotitanium, 0.1 to 0.5 percent of graphite, 5 to 15 percent of iron powder, 0.5 to 2 percent of nitride and 1 to 3 percent of aluminum magnesium alloy. A sheath of the special flux-cored wire is a low-carbon steel strip. The special flux-cored wire can be suitable for open arc welding or submerged arc welding. The series flux-core wire for surfacing can carry out surfacing repair and reproducing on the shaft and gear parts under the conditions that preheating is free before surfacing and heat treatment is free after surfacing. The surfacing metal has high crack resistance. The performance of the repaired parts is equal to or even superior to that of the original parts. The special flux-cored wire is convenient to use on site. The hardness range is between HRC20 and HRC45. The service life of the repaired parts is about 3 times longer than that of the original parts.

The invention provides a big vertical masonry joint hidden arc welding tube fast production method belonging to the processing and forming fields of metal plate and relating to the bending processing and forming technology of metal plate which is mainly used for the fast production of the big vertical masonry joint hidden arc welding tube. The invention adopts continuous array rollers of a coil stock to form, high frequency prewelding on line, then utilizing a off-line automatic submerged arc welding to carry out the inner welding and outer welding of the welded pipe as well as expanding, water pressure and nondestructive examinations; thereby realizing the high efficiency production of the big vertical masonry joint hidden arc welding tube products. The invention adopts a plate-coiling mode to supply materials, cutting materials, shearing and butt welding, utilizes milling edge to finish the online-processing of a divided edge beside the plate, primary roller forming, fine roller forming, high frequency prewelding after a rough material is continuously formed by the array rollers and sawing as well as baiting and the steel tube rough material needed by a hidden arc welding working procedure can be acquired through online dimension fixing and cutting off; hidden arc inner welding and hidden arc outer welding, inner control examination, expending, water pressure test, repairing ends by machinery are carried out on the steel rough material to exam to acquire a finished product. The technique has a reasonable design and has the advantages of good steel tube forming quality and high production efficiency as adopting the array rollers to form and high frequency prewelding; thereby ensuring the overall production efficiency of the technique and the welding line quality can also be ensured reliably.

The invention discloses a submerged-arc welding root welding and back chipping process of a thick plate with a K-type groove. The K-type groove is an asymmetric K-type groove, an upper open angle and a lower open angle of the groove are both 45 degrees to 50 degrees, and truncated edges are not reserved at the root. During assembly, groove clearance of 2mm to 3mm is reserved. During welding, solid gas protection welding wires under pulse current are adopted for backing welding of a root pass of the front side of a K-type groove test piece, and after the root pass is thoroughly fused, a part of weld metal penetrates through the reverse side of the groove to achieve backing welding. After welding, back chipping of the reverse side is performed. Finally, gas shielded welding under large current is adopted for fusion welding of the roof of the reverse side groove, and gas rich in argon is used as protective gas. The submerged-arc welding root welding and back chipping process reduces time for slag removal of root pass of submerged-arc welding and polishing and finishing of the reverse side groove of the welding test piece, improves welding efficiency by more than 30%, removes a carbon arc gouging process, decreases welding noises and dust emission, lowers labor intensity of welders and reduces time for damaging workers under high-decibel noises.

The invention discloses a production method of a 150-400mm thick steel plate for plastic moulds and belongs to the field of metal materials. Continuous cast slab is used as raw material to produce the 150-400mm thick steel plate by the production method and comprises, by weight percent, 0.20-0.40% of C, 0.20-0.50% of Si, 1.00-1.60% of Mn, not more than 0.008% of S and P, 0.10-0.50% of Mo, 1.40-2.0% of Cr, 0.01-0.04% of V, and not more than 0.20% of other alloy elements (Nb, Ti and Ni). The high thickness slab can be produced by full-vacuum electron beam welding or by combined process of gas shielded welding, submerged-arc welding and vacuum electron beam welding and is then subjected to heating, rolling, slow cooling and heat treatment procedures, ultrasonic testing qualified rate of the produced steel plate for plastic moulds reaches more than 98%, the hardness is even, and the steel plate has excellent machinability, wear resistance and polishability and is suitable for production of various plastic moulds.

The invention discloses a welding method of a deck structure of a stainless steel compound plate of a railway steel bridge, which comprises the following steps: selecting structural steel for a bridge with thickness of 16-20mm as a base layer, selecting austenitic stainless steel with thickness of 2-4mm as a multiple layer, and removing 3-6mm of cladding material materials at each of two edges of welding grooves in advance, wherein the groove angle is 45-65 degrees, and the groove spacing is 4-8mm; the method comprises the following steps: firstly, assembling positioned welding, and then, carrying out backing welding by CO2 gas shielded welding; then, carrying out welding of the base layer by submerged-arc welding; and finally, carrying out welding of a transition layer and the multiple layer by the CO2 gas shielded welding. By adopting a specific groove type, the invention eliminates uncertain human factors and solves the problems that the thickness of the deposited metal of the base layer is insufficient, the multiple layer can be molten by mistake when the substrate layer is welded, and the like; the reverse formation is good, so that the reverse back gouging process is omitted; and the invention has the advantages of good assembly quality and easy realization of mechanization and automation, improves the production efficiency, and is convenient for ensuring the corrosion resistance of the multiple layer.

The invention discloses a welding technology of submerged-arc welding of an X-shaped groove of a medium plate, which adopts the following technological steps: (1) when the front surface is welded: the welding current is 450 to 480A; the welding voltage is 25 to 26V; the welding speed is 54 to 58cm/min; and the rod extends by 30 to 35cm; (2) and when the back surface is welded: the welding currentis 600 to 640A; the welding voltage is 30 to 32V; the welding speed is 44 to 47cm/min; and the rod extends by 35 to 40cm. The welding technology has the advantages that the submerged-arc welding is directly adopted for priming; the back chipping is not required on the back surface of a welding seam; the appropriate welding current and voltage is selected and the welding speed is reasonably matched; the problem on the complicated welding method in the prior art is solved; the qualification rate of the welding seam flaw detection is simultaneously guaranteed; the working time of the welding is reduced; and the welding material is saved.

The invention provides a field welding method of a domestic A335 P91 high-pressure thick-wall pipe, and belongs to the technical field of welding. A welded part of a welded pipe is processed as a double-V-shaped groove; a process of welding 3 layers for bottoming by using manual argon arc welding GTAW and filling a cover surface by using automatic submerged arc welding SAW is adopted; multi-layer and multi-pass welding is adopted; each layer of welding line sections is decreased; and the welding line crystallization conditions are changed, so that the toughness of a welding joint is improved, an overthick welding bead is prevented from narrowing a heat affected zone, and a softening belt of the welding joint is prevented from generating cracks in long-time operation at high temperature; a small-diameter welding wire with a diameter of not more than 2.5 mm and a low-hydrogen welding agent are adopted to weld to reduce the linear energy in the welding process, so that grains of base metal are refined, and the possibility of generating such defects as air holes and cracks in welding lines is reduced; and compared with a traditional manual welding method, the field welding method effectively shortens the heat treatment and welding period, improves the welding line quality and the welding efficiency, relieves the labor intensity of welders, and saves the construction cost.

The invention provides a high-strength austenitic stainless steel submerged-arc welding wire and belongs to the technical field of welding wires. Chemical components of the stainless steel welding wire comprise, by mass, C<=0.025%, Si<=1.00%, Mn<=2.50%, P<=0.020%, S<=0.010%, 12.00-14.00% of Ni, 18.00-20.00% of Cr, 2.00-3.00% of Mo, 0.05-0.10% of N, Nb<=0.150% and the balance iron. High-temperature ferrite delta in cast-condition austenitic stainless steel is 8-15%. By means of the welding wire, the problem that a device is poor in weld line mechanical property when the device runs at high temperature for a long time is solved. The welding wire can be mainly used for welding materials for energy industry, chemical industry and the like at high temperature and under high pressure.