338results about How to "Good welding performance" patented technology

The invention discloses a high-strength silver-free copper-based brazing filler metal which is composed of P, Sn, Ni and Cu. The high-strength silver-free copper-based brazing filler metal is low in cost, safe, environmentally friendly and good in welding effect; through the adding of Sn and Ni, the melting point of brazing filler metal alloy is reduced, and the tensile strength and wettability of the brazing filler metal alloy are enhanced.

The present application relates to the technical field of lead-free solder paste, and more specifically, to a lead-free solder paste with low voiding rate and precision welding and a preparation method thereof, which is prepared from the following raw materials in parts by weight: 70-90 parts of tin, 1-2 parts of silver, 3-6 parts of copper, 2-5 parts of magnesium fluorosilicate, 3-6 parts of nano-carbon powder, 4-5 parts of rare earth oxide and 20-30 parts of flux. The above formula can reduce the voiding rate in the welding process, improve the wettability of the lead-free solder paste, and improve the quality and reliability of the welding points.

The invention discloses a production method of a 500MPa-grade galvanized dual-phase steel strip for an automobile bracket. The 500MPa-grade galvanized dual-phase steel strip comprises the following chemical components in percentage by mass: 0.05-0.08% of C, less than or equal to 0.25% of S , 1.5-1.8% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, 0.015-0.060% of Alt, 0.01-0.25% of Cr, 0.0010-0.0030% of Ca and the balance of Fe. The production method specifically comprises the following steps: a smelting-continuous casting production process flow; a hot rolling production technological process; pickling and cold rolling; and carrying out continuous hot galvanizing and finishing processes. The 500MPa-grade galvanized dual-phase steel for the automobile bracket has the characteristics of low yield ratio, high work hardening capacity, good corrosion resistance, welding performance, no yield elongation, no room-temperature aging, high elongation and the like, and can meet the requirements of users on light-weight and high-corrosion-resistance material selection.

The utility model discloses a welding tool for pipeline butt welding processing, which relates to the technical field of processing equipment and comprises a base, side seats are arranged at two ends above the base, the front end and the rear end of each side seat are rotatably connected with a lead screw and a sliding rod respectively, roller frames are arranged at two ends of each side seat, the outer ends of the roller frames are in threaded connection with the lead screws respectively, and the outer ends of the roller frames are in threaded connection with the sliding rods respectively. The other ends of the outer sides of the roller frames are slidably connected with the sliding rods correspondingly, a plurality of guide rollers are rotationally connected into the roller frames, two pipelines are hoisted into the two roller frames through hoisting equipment and make contact with the guide rollers in the roller frames, during welding, a welding machine is installed on the supporting frame, a third motor drives an outer gear to rotate through a rotating shaft after working, and the outer gear is driven to rotate through the rotating shaft. The outer gear can drive the meshed gear ring to rotate after rotating, the gear ring can drive the welding machine on the supporting frame to conduct constant-speed welding around the outer walls of the two pipelines in a self-rotation mode, the heavy pipelines do not need to be rotated in the welding mode, and stability after welding is indirectly improved.

The utility model relates to a floating type offshore wind power suction anchor foundation mooring lifting lug structure which comprises a suction anchor cylinder body, a main eye plate and a cylinder body thickening plate, the cylinder body thickening plate is fixed on the inner side wall of the suction anchor cylinder body, the main eye plate is fixed on the outer side surface of the suction anchor cylinder body, and the cylinder body thickening plate is fixed on the inner side wall of the suction anchor cylinder body. The main eye plate penetrates through the side wall of the suction anchor cylinder and the cylinder thickening plate and is fixedly connected with a first connecting plate, a second connecting plate is fixed to the other side of the first connecting plate, and the second connecting plate is fixed to the inner side wall of the other side of the suction anchor cylinder. According to the utility model, the suction anchor cylinder body can form a whole with a stable structure.

The invention discloses a high-efficiency heat dissipation device and electronic equipment. The high-efficiency heat dissipation device comprises an upper cover plate, a bottom cavity and a plurality of heat dissipation fins, a cavity is defined by the upper cover plate and the bottom cavity; the top surface of the upper cover plate is covered with a first solder layer, the top surface of the upper cover plate is provided with a mounting through groove downwards communicated with the cavity, and the periphery of the top end of the mounting through groove is chamfered to form an annular flow guide surface surrounding the mounting through groove; the cooling fins are internally provided with flow channels, the cooling fins are provided with flow channel connector parts corresponding to outlets and inlets of the flow channels respectively, the flow channel connector parts are inserted into the mounting through grooves, the interiors of the flow channel connector parts are downwards communicated with the cavity, and annular gaps are formed between the peripheral surfaces of the flow channel connector parts and the annular flow guide surface; and the first solder layer on the top surface of the upper cover plate is melted and then flows into the annular gap along the annular flow guide surface, so that sealing welding fixation is formed between the peripheral surface of the runner interface part and the annular flow guide surface. Therefore, the problem that the hidden danger of working fluid medium leakage easily exists at the welding position is effectively solved, and the heat dissipation effect is good.

The invention discloses low-carbon equivalent ferrite type pipeline steel and a construction method, and belongs to the technical field of metallurgical production processes. The invention provides the low-carbon equivalent ferrite type pipeline steel which has ultralow carbon equivalent and meets the matching requirement of strength and toughness of X52 pipeline steel and the construction method. The low-carbon equivalent ferrite type pipeline steel is a hot-rolled steel strip with the thickness specification of 8.0-12.0 mm, and comprises the following components in percentage by weight: 0.020-0.050% of C, 0.10-0.25% of Si, 0.70-1.00% of Mn, less than or equal to 0.008% of P, less than or equal to 0.003% of S, 0.020-0.040% of Als, 0.015-0.025% of Nb, 0.010-0.020% of Ti, less than or equal to 0.0050% of N and the balance of Fe and inevitable impurities, and the cold crack sensitivity index Pcm of the hot-rolled steel strip is less than or equal to 0.1%. The construction method comprises the steps of molten steel smelting, calcium treatment, plate blank preparation, plate blank reheating, plate blank rolling, cooling and coiling, in the plate blank preparation process, molten steel which is smelted to be qualified is directly and continuously cast on a continuous casting machine to form a plate blank meeting the requirement, and after the continuous casting plate blank is slowly cooled for more than 48 hours, the plate blank is fed into a heating furnace to be heated in the furnace for 150-230 min; and after discharging, carrying out rough rolling, finish rolling and laminar cooling, and coiling to obtain the low-carbon equivalent ferrite type pipeline steel.

The welding device comprises a movable frame, an oil collecting pipe welding clamp and an automatic welding machine, telescopic rods are arranged on the left side and the right side of the outer portion of the movable frame, an upper supporting plate is arranged on the tops of the telescopic rods, and a linkage positioning mechanism is installed on the upper supporting plate; synchronous locking of the multiple cooling fins is achieved through the linkage positioning mechanism; an oil collecting pipe welding clamp is arranged below the inner side of the movable frame, and the oil collecting pipe is clamped and positioned through the oil collecting pipe welding clamp; a sliding rod is installed below the oil collecting pipe welding clamp, a sliding base is installed outside the sliding rod in a sliding mode, a multi-axis mechanical arm is arranged above the sliding base, an automatic welding machine is installed at the top end of the multi-axis mechanical arm, and welding work of the cooling fins and the oil collecting pipe is completed through the automatic welding machine. The welding device has the advantages of being reasonable in structure, convenient to use, good in welding effect and capable of improving working efficiency.

The invention discloses a low-yield-ratio carbon-manganese low-temperature steel plate and a production method thereof, the steel comprises the following chemical components in percentage by mass: 0.07%-0.08% of C, 0.15%-0.25% of Si, 1.30%-1.40% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.10%-0.20% of Ni, 0.012%-0.017% of Nb, 0.008%-0.020% of Ti, 0.020%-0.050% of Al and the balance of Fe and inevitable impurities, the structure type of the steel is ferrite and pearlite, and the grain size is 9-10 levels. The process comprises the steps of converter smelting, LF refining, vacuum degassing, continuous casting, heating, rolling and finishing. The yield strength of the steel plate is 315-440 MPa, the tensile strength is 440-520 MPa, the yield ratio is smaller than or equal to 0.85, the elongation is larger than or equal to 30%, and the-60 DEG C impact Akv is larger than or equal to 80 J; and excellent welding and firework process properties are achieved.

The utility model discloses a special device for automatic laser welding of an ultrathin metal drum, which belongs to the technical field of welding equipment and comprises a workbench, a laser welding component and a clamp component, the clamp component comprises a first fixing plate, a first driving motor, a first half die, a second half die, a middle plate, a cylinder component and a second fixing plate, a first groove is formed in the first half die, a second groove is formed in the second half die, the metal barrel blank comprises a first half blank and a second half blank, the first groove is used for containing the first half blank, and the second groove is used for containing the second half blank. According to the die, the two half dies and the two grooves are arranged, and the two grooves have a good fixing effect on a blank, so that the blank is prevented from sliding; the clamp assembly clamps a metal barrel blank, the laser welding assembly performs automatic laser welding, the welding efficiency is high, the welding effect is good, and the product percent of pass is high.

The invention relates to the technical field of constructional engineering, and discloses a construction site steel structure welding device for constructional engineering, which comprises a base, the outer wall of the base is fixedly connected with the outer wall of a sliding table, the outer wall of the sliding table is fixedly connected with one end, close to the sliding table, of a top plate, and the bottom of the top plate is fixedly connected with the top of a welding gun. According to the angle welding device, the locking assembly is arranged, the rotary table is adjusted to the preset angle through the locking assembly and locked, the situation that a corresponding included angle cannot be kept due to thermal stress after angle welding of a steel structure is conducted is prevented, and the steel structure is stably kept at the preset angle; according to the construction site steel structure welding device, the steel structure is kept stable in the welding process and after welding, meanwhile, stable clamping force prevents the situation that due to the fact that the steel structure is long, the two sides fall down, the welding position deviates, and welding is not standard, and the construction site steel structure welding device used for constructional engineering can be normally used.

The invention discloses a preparation method of a PVD (Physical Vapor Deposition) semiconductor reaction cavity water-cooling plate assembly and the water-cooling plate assembly, and relates to the technical field of semiconductor water-cooling plate preparation. The method comprises the steps that according to the size of a target base, an oxygen-free copper material is cut, then rough machining is conducted, and a base blank is obtained; cutting the oxygen-free copper material according to the size of the target cover plate, and performing rough machining to obtain a cover plate blank; performing heat treatment on the cover plate blank to obtain a heat-treated cover plate blank; after a base blank and the heat treatment cover plate blank are assembled, welding is conducted, and an assembling assembly is obtained; performing water pressure detection on the assembly component under the water pressure of 0.6-0.8 MPa; and carrying out finish machining on the assembly component passing through the water pressure detection, and then carrying out helium leak detection to obtain a finished product water-cooling plate component. The water cooling plate assembly can be tightly combined with the semiconductor reaction cavity, the welding sealing performance is high, the heat conduction efficiency is high, heat is taken away through water cooling transfer, semiconductor equipment can be rapidly cooled, and the cooling efficiency is high.

The invention discloses NM450 steel with low carbon equivalent and high toughness and a production process thereof, and relates to the technical field of steel production, and the NM450 steel comprises the following chemical components in percentage by mass: 0.15%-0.20% of C, 0.15%-0.35% of Si, 0.30%-0.60% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0020% of S, 0.65%-0.85% of Cr, 0.25%-0.50% of Mo / Ni, 0.002%-0.006% of Ti, 0.050%-0.080% of Nb, 0.020%-0.050% of V, 0.0010%-0.0030% of B, 0.070%-0.090% of Alt, less than or equal to 0.0050% of N, less than or equal to 0.0003% of H, less than or equal to 0.55% According to the steel plate, the yield strength is larger than or equal to 1100 MPa, the tensile strength is larger than or equal to 1400 MPa, the ductility is larger than or equal to 12%, the surface Brinell hardness is larger than 430 HB, the core Brinell hardness is larger than 400 HB, the low-temperature impact energy at the temperature of-40 DEG C is larger than or equal to 60 J, and the welding performance is good.

The invention relates to the technical field of aero-engine maintenance, in particular to a high-aluminum-titanium cast high-temperature alloy welding repair method which aims at solving the problems that the aluminum-titanium content is larger than or equal to 9%, gamma phase enhanced cast high-temperature alloy is poor in welding performance, and the welding repair qualification rate is low due to the fact that hot cracks are likely to be generated. Firstly, a bench worker is used for polishing a U-shaped groove to remove cracks, then a low-aluminum-titanium layer is formed on the surface of a to-be-welded area through a pulse high-activity high-temperature bond separation reaction technology so as to improve weldability of a part, then a low-heat-input TIG welding technology is adopted for surfacing repair, the one-time welding qualification rate can reach 75% or above, the room-temperature strength of a weld joint reaches 95% or above of a base material, and the welding quality is improved. The high-temperature tensile strength reaches more than 60% of that of a base material, the fatigue strength is high, and the method has the advantages of simplicity and convenience in operation, no need of special preheating and slow cooling, high efficiency, low cost and the like, is suitable for various workpieces with complex structures, and is easy to realize batch processing.

The invention discloses a welding device for mining mechanical equipment manufacturing, and belongs to the technical field of mining mechanical equipment manufacturing. A welding device for mining mechanical equipment manufacturing comprises a workbench and mining mechanical equipment parts arranged on the workbench, a welding assembly is arranged at the top of the workbench, two moving boxes are arranged on the surface of the workbench, clamping assemblies are arranged in the moving boxes, and first motors are fixedly installed outside the moving boxes; according to the welding device for manufacturing the mining mechanical equipment, parts needing to be welded are placed above the two moving boxes correspondingly, a first motor is started to drive a first screw to rotate, and a vertical plate and a clamping plate at the top are driven to slide in the direction of a U-shaped frame through the vertical plate in threaded connection; and therefore, the mining mechanical equipment parts are rapidly clamped and fixed through the clamping plates and the U-shaped frame, the welding efficiency of the mining mechanical equipment parts is effectively improved, and a large amount of operation time is saved.

The invention relates to the technical field of welding fixing devices, in particular to a fixing device for welding a cold storage heat preservation door, which comprises a bottom plate and two fixing plates, the two fixing plates are fixedly connected to the two ends of the upper surface of the bottom plate respectively, a sliding rod is fixedly connected between the two fixing plates, and a mounting box is slidably connected to the sliding rod; a welding gun is transversely limited through the mounting box and a sliding rod, the welding gun is longitudinally limited through a clamping block and a clamping hole, the height from the welding gun to a welding seam is kept consistent during welding, and the welded welding seam is kept straight and does not incline; and during welding, the impact head is continuously driven to impact a welding seam which is just welded, welding slag on the surface of a crator is crushed and cleaned, the situation that the welding slag is rapidly condensed and difficult to clean is avoided, cavities are prevented from being contained in the welding seam, the welding effect is guaranteed, and the welding strength is high.

The invention discloses a high-aluminum rare earth weathering steel for a bridge damper and a preparation method thereof, comprising the following elements: Al: 2.0-4.0%, Si: 0.30-2.0%, Mn: 0.6-0.8%, Ti: 0.02-0.15%, V: 0.05-0.20%, Cu: 0.18-0.30%, Ni: 0.15-0.25%, B: 0.12-0.20%, C: 0.06-0.09%, P: 0.018-0.40%, S: 0.003-0.008%, Re: 0.0075-0.080%, and the remainder is Fe and unavoidable impurities. The preparation method comprises: raw material pretreatment; high temperature smelting; casting and rolling; cutting and grinding; and surface final treatment. By combining various elements and optimizing the surface treatment method, the weathering steel obtained in the present invention has the characteristics of high strength, easy welding, good weather resistance and good shock-absorbing and damping performance. It is used as the skeleton material in the bridge damper, which can significantly improve the seismic performance, durability and vibration control effect of the bridge.

The invention discloses a production method of a 460MPa-grade high-strength steel plate with the thickness of 50-80mm for wind power equipment. The production method comprises the following main process steps and parameters: step 1, smelting and continuous casting production process flow: KR desulfurization, converter treatment, LF refining, RH vacuum treatment, slab continuous casting and slow cooling; secondly, the plate blank is put into a furnace to be heated; the in-furnace time, the soaking time and the tapping temperature of the plate blank are strictly controlled, the in-furnace time is larger than or equal to 220 min, the soaking time is 30-60 min, and the tapping temperature is 1230 + / -20 DEG C; thirdly, rolling the plate blank, specifically including rough rolling and finish rolling; fourthly, the steel plate is straightened; and 5, quenching and tempering heat treatment of the steel plate. The method is simple to operate and suitable for industrial production. The quenched and tempered steel plate produced through the method is high in strength, good in impact toughness and excellent in forming performance and welding performance, and the mechanical performance and the technological performance meet the technical requirements of users.

The utility model discloses welding equipment for electric vehicle part production, and relates to the technical field of electric vehicle part production, the welding equipment comprises a carrier plate, a welding piece is arranged above the carrier plate, a fixing block is fixedly arranged at the upper end of the carrier plate, clamping pieces are rotatably arranged on the two sides of one end of the fixing block, and the clamping pieces are arranged on the two sides of the other end of the fixing block. The welding equipment comprises a fixing block, a rotating disc is arranged at one end of the fixing block, a telescopic rod is fixedly arranged at one end of the rotating disc, one end of the telescopic rod penetrates through the fixing block and extends to one side of the fixing block, and an adjusting pipe is arranged on one side of the fixing block. The electric vehicle part welding device is simple in structure, convenient to operate, good in fixing effect, capable of improving the stability of welding machining and enhancing the welding quality, simple in adjusting structure design, convenient to operate, capable of achieving position adjustment of a welding structure in three axial directions, good in welding effect in cooperation with electric vehicle parts and high in universality.

The invention discloses an optical fiber laser cooling heat dissipation device and a heat dissipation method, and belongs to the field of optical fiber lasers, the optical fiber laser cooling heat dissipation device comprises a box body, a first installation area and a second installation area are arranged in the box body in a separated mode, an optical fiber laser and a cooling plate are arranged in the first installation area, and a liquid cooling medium is contained in the cooling plate; the second mounting area is provided with a heat dissipation assembly, and the heat dissipation assembly is connected with the cooling plate so as to cool the liquid cooling medium; the optical fiber laser comprises a pumping source assembly, a concave portion is correspondingly arranged on the cooling plate, and the outer wall of the pumping source assembly and the concave portion are arranged in a coplanar mode so that the surface of the pumping source assembly can make contact with the liquid cooling medium. According to the cooling and heat dissipation device for the optical fiber laser, the concave part is arranged on the cooling plate, and the pumping source assembly and the cooling plate are arranged in the same plane, so that the liquid cooling medium in the cooling plate directly cools the pumping source assembly, the cooling effect on the optical fiber laser is greatly improved, and it is ensured that the working temperature of the optical fiber laser is accurate and controllable.

The invention relates to the technical field of metal materials and processing thereof, and discloses a red copper foil sheet for electric flexible connection and a preparation process thereof, and the red copper foil sheet is prepared from the following components in percentage by weight: a base material: more than or equal to 99.95% of high-purity copper Cu; the content of phosphorus (P) is 0.001%-0.005%; silver (Ag): 0.01% to 0.05%; zirconium (Zr): 0.002%-0.01%; zinc (Zn): 0.002%-0.01%; 0.001% to 0.005% of rare earth elements (Ce and La); the oxygen content of the copper alloy is less than or equal to 0.005%. By means of the component design scheme of collaborative optimization of multi-element microalloying and rare earth modification, it is ensured that the red copper foil has high conductivity, high ductility and excellent welding performance, and compared with the technical scheme of single-element deoxidation or anti-softening treatment in the prior art, the copper foil has the advantages that the copper foil has high conductivity, high ductility and excellent welding performance.

The invention provides welding equipment for a stainless steel rocket storage tank. The welding equipment comprises a supporting base, a scalloped segment rotating supporting assembly, a scalloped segment inner tube, a top cover inner tube and a lifting shaft. The scalloped segment rotary supporting assembly is arranged on the supporting base so as to support the scalloped segment inner tube and the bottom of the scalloped segment; the scalloped segment inner tube is provided with a molded surface matched with the inner side face of a scalloped segment, and the inner side face of the scalloped segment is supported so as to weld a longitudinal seam of the scalloped segment. The lifting shaft is arranged in the middle of the supporting base, the top cover inner tube is fixedly arranged on the lifting shaft, and the top cover inner tube is used for supporting a top cover so as to weld a scalloped segment ring and the top cover. The welding equipment can improve the welding seam performance, and can simplify the manufacturing process of the elliptical head.

The invention discloses a production method of zinc-plated low-alloy high-strength steel with the yield strength of 380MPa for an automobile structure. The production method comprises a smelting-continuous casting production process; the molten steel for a casting machine comprises the following components in percentage by mass: 0.05 to 0.08 percent of C, less than or equal to 0.06 percent of Si, 0.6 to 0.9 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.015 to 0.050 percent of Alt, 0.02 to 0.04 percent of Nb, 0.02 to 0.04 percent of Ti, 0.0008 to 0.0020 percent of Ca and less than or equal to 0.0070 percent of N; (2) a hot rolling production process; (3) pickling and cold rolling; and (4) carrying out continuous hot galvanizing and finishing processes. The mechanical properties of the galvanized low-alloy high-strength steel meet the requirements that the yield strength ReL is 380-480 MPa, the tensile strength Rm is 440-560 MPa, and the ductility A80 is larger than or equal to 19%.

The invention discloses a manufacturing method of thin-gauge low-yield-ratio Q500qE bridge steel, and belongs to the field of steel manufacturing. The method comprises the steps of component design, casting, heating, rolling, cooling and the like, and finally the required finished steel plate is obtained. The low-temperature impact resistance of the steel plate can be ensured while high strength and low yield ratio of the steel plate are effectively ensured under the condition of low alloy addition. Besides, controlled rolling, cooling and heat treatment processes are combined, the steel plate in the TMCP + T state is obtained, a microstructure with refined ferrite and bainite as main components is obtained in the whole plate thickness, the steel plate has the mechanical property characteristics of high strength, low yield ratio and high toughness, and the low-temperature impact toughness is that the fracture fiber section rate can reach 85% or above at the temperature of-40 DEG C. According to the steel plate, the target performance requirement can be met, the plate shape of the steel plate can be guaranteed, the steel plate has good comprehensive mechanical performance, in addition, the manufacturing cost is low, the carbon content is low, the weldability is greatly improved, and the steel plate has high manufacturability.

The invention belongs to the technical field of steel and iron materials, and particularly relates to freeze-thaw-resistant frozen soil corrosion-resistant low-alloy structural steel and a preparation method thereof, the freeze-thaw-resistant frozen soil corrosion-resistant low-alloy structural steel adopts a component design completely different from that in the prior art to meet the freeze-thaw-resistant frozen soil corrosion-resistant requirements, meanwhile, the component design is simplified, and the cost is reduced. Zr-Ti-RE composite deoxidation and microalloying freeze-thaw-resistant steel controllable preparation is supplemented, the environmental fracture sensitivity is reduced, and the integrated design of the freeze-thaw-resistant steel component structure is achieved; through the low-carbon equivalent design, the steel plate has excellent welding performance; and Ti, Zr and RE composite microalloying is adopted, and TMCP rolling parameter regulation and control are matched, so that the steel plate is small in grain size and high in obdurability. The freeze-thaw corrosion resistant steel is particularly suitable for structural materials of plateau frozen soil roads, railways, bridges and the like used in low-temperature and freeze-thaw environments, and the material has the remarkable characteristics of high strength, easiness in welding, freeze-thaw resistance and the like besides low-temperature toughness and excellent performance.

The invention relates to low-cost 550MPa grade steel for non-preheating welding of coal mine machinery and a manufacturing method thereof, the low-cost 550MPa grade steel comprises the following chemical components in percentage by weight: 0.03-0.06% of C, 0.25-0.45% of Si, 1.3-1.7% of Mn, less than or equal to 0.008% of P, less than or equal to 0.003% of S, 0.025-0.045% of Nb, 0.006-0.020% of Ti, 0.0014-0.0022% of B, 0.020-0.030% of Al and the balance of Fe and other inevitable impurities, and the welding crack sensitive index Pcm is less than or equal to 0.18%; and the carbon equivalent CEV is less than or equal to 0.38%. Compared with the prior art, the low-C content is adopted in the component design, precious alloy elements such as Ni, Cr and Mo are not added, and under the condition that tempering is not needed in the process, it can be guaranteed that the yield strength of the obtained steel plate is larger than or equal to 550 MPa, the tensile strength is larger than or equal to 670 MPa, the impact energy at the temperature of-20 DEG C is 210-380 J, and preheating-free welding can be achieved when the environment temperature is-10 DEG C or above.