52results about How to "Increased impact value" patented technology

A one-piece toroidal end mill having an axis of rotation is provided. The end mill includes a shank section and a fluted section. The shank section extends along the axis of rotation. The fluted section extends along the axis of rotation, and has a first end, an outer surface, and a plurality of teeth. The first end is integrally attached to the shank section. Each of the plurality of teeth has a cutting surface and a shoulder surface. The cutting surface includes a cutting edge. The shoulder surfaces intersect with one another to form a center void disposed between the cutting surfaces.

The invention discloses a pile main bolt manufacturing technique of a million kilowatt grade nuclear power station. The manufacturing technique includes material-selecting, melting, heating, forging, cooling, after-forging heat treatment, defect-detecting, and forging capability heat treating. When selecting the material, the microelement content of the materials is controlled, the heat preserving duration in the intermediate temperature stage is prolonged, the heat raising and the heat preserving duration in the high temperature stage are reduced, the distortion volume in the course of the forging is controlled between 30 percent and 70 percent, the forging rate reaches 5 above; after-forging heat treatment, ultrasonic defect detecting, and forging capacity heat treating are conducted when the forging is finished. The main bolt produced according to the manufacturing technique of the invention can improve the impact value under the circumstance that the intensity keeps unchanged, theproduct can meet the RCC-M standard requirements completely, and the reliability and the safety of the pile pressure container using the main bolt of the million kilowatt grade nuclear power station can be ensured.

The invention discloses martensitic stainless steel, which comprises the following components in percentage by mass: 0.10-0.15 percent of carbon, 0.20-0.50 percent of silicon, 0.50-1.50 percent of manganese, 2.00-4.00 percent of nickel, 15.00-17.00 percent of chromium, 0.03-0.30 percent of molybdenum, 0.020-0.200 percent of nitrogen, 0.01-0.10 percent of rare earth, less than or equal to 0.25 percent of copper, less than or equal to 0.025 percent of sulfur, less than or equal to 0.040 percent of phosphorous and the balance of Fe and inevitable impurities. The martensitic stainless steel has strength and plasticity, high low-temperature impact ductility and corrosion resistance, and can be applied to a hydraulic cylinder shaft for manufacturing a ship. The invention also discloses a manufacturing method of the martensitic stainless steel.

A fillet rolling nodular cast iron crankshaft is made of QT800-6 nodular cast iron materials and has a high elongation rate and a higher impact value. Rolling force can be effectively improved, transition fillets of a main journal, a rod journal and a crank arm are of undercutting groove structures, critical sizes such as linearity and cylindricity of the main journal and the rod journal can be effectively ensured, and swelling of journal surfaces caused by flow of parts of materials is prevented in the rolling process. By the aid of the strengthening technology of 'journal quenching and fillet rolling', the fillet rolling nodular cast iron crankshaft can obtain high fatigue bending moment performance, the fatigue bending moment performance of the fillet rolling nodular cast iron crankshaft exceeds that of a forged steel nitriding crankshaft and approaches to the level of a forged steel quenching crankshaft, reliability can be ensured, and cost can be remarkably reduced.

The invention discloses a high tensile insulator with the functions of explosion-proof and lightning protection and a lightning arrester with the function of explosion-proof in the electrical equipment field. The high tensile explosion-proof lightning protection insulator comprises an explosion-proof lightning protection device body containing cell-combination in series with effective large planedischarging gap valve box, where large current can be distributed evenly and can discharge under constant pressure and the inner periphery of the cavity opening is provided with a bulb and an iron capwhich lie in a rabbet platform, a trough type hoop, a joint foot pole of the base of a hollow round platform and a tensile reinforcement combination used for preventing the dislocation caused by drawing. The explosion-proof lightning arrester of the invention comprises an explosion-proof lightning device body containing cell-combination in series with effective large plane discharging gap valve box, where large current can be distributed evenly and can discharge under constant pressure and a fixed shelving combination. The beneficial effect of the invention is that the high tensile explosion-proof lightning protection insulator and the explosion-proof lightning arrester can bear large surging, has low residual voltage and low energy loss, can resist electric sleet disaster and is safe andreliable.

The invention discloses a series-connected double-wire type combined welding wire for CO2 gas shield high-speed flat fillet weld. The series-connected double-wire type combined welding wire for the CO2 gas shield high-speed flat fillet weld comprises an antecedent electrode welding wire and a posterior electrode welding wire, the antecedent electrode welding wire and the posterior electrode welding wire are connected in series, the antecedent electrode welding wire is formed by a first steel-tape sheath and metal cored powder contained inside the first steel-tape sheath, the weight of the metal cored powder is 10-30% of the total weight of the antecedent electrode welding wire, the antecedent electrode welding wire is high in deposition rate, the quantity of generated slag is small in a welding process, and a small amount of added fluoride enables the electric arc to be more stable. The posterior electrode welding wire is formed by a second steel-tape sheath and welding flux powder contained inside the second steel-tape sheath, the weight of the welding flux powder is 10-30% of the total weight of the posterior electrode welding wire, the content of the diffusible hydrogen of deposited metal can be reduced to be lower than 5ml / 100g through the posterior electrode welding wire, and CO released by combustion of an undercoat can be reduced by Al and Mg in the welding process. A small amount of titanium and boron are added in both the metal cored powder and the welding flux powder, and the impact value of the deposited metal can be improved greatly. When welding is carried out at the welding speed higher than 1.5m / min, the combined welding wire is excellent in welding process, and good paint resistant performance can be obtained.

The invention discloses a steel plate with excellent low-temperature toughness. The steel plate comprises the following chemical elements in percentage by mass: 0.02-0.15% of C; 0.10% to 0.5% of Si; 0.30% to 1.60% of Mn; 0.10% to 1.00% of Cr; 0.30% to 1.00% of Ni; 0.005% to 0.10% of Ti; 0-0.60% of Mo; 0.10% to 0.80% of Cu; 0.01% to 0.06% of Al; 0.003-0.06% of Nb, 0-0.08% of V, and 0 < N < = 0.035%; and the balance of Fe and other inevitable impurities. In addition, the invention also discloses a manufacturing method of the steel plate with excellent low-temperature toughness, which comprises the following steps: (1) smelting and casting; (2) heating; (3) rolling; and (4) cooling.

The invention relates to a spheroidal graphite ausferrite cast iron grinding ball suitable for being used in a semi-automatic grinding machine and a preparation process. The spheroidal graphite ausferrite cast iron grinding ball is prepared from the following components in percentage by mass: 3.2 to 3.9 percent of carbon, 2.30 to 2.93 percent of silicon, 0.96 to 2.80 percent of manganese, 0.21 to 0.90 percent of chromium, 0.11 to 0.60 percent of copper, 0.10 to 0.80 percent of molybdenum, 0.10 to 0.68 percent of vanadium, 0.10 to 0.78 percent of titanium, 0.01 to 0.09 percent of niobium, greater than or equal to 0 and less than 0.05 percent of phosphorus, greater than or equal to 0 and less than 0.03 percent of sulfur, 0.03 to 0.05 percent of magnesium, 0.02 to 0.03 percent of rare earth elements and the balance of iron. The preparation process comprises the following steps: firstly, performing casting forming to prepare a cast grinding ball; secondly, performing thermal treatment on the cast grinding ball to prepare the spheroidal graphite ausferrite cast iron grinding ball. The hardness of the heart part of the spheroidal graphite ausferrite cast iron grinding ball disclosed by the invention is 54 HRC, and the surface hardness is 58 HRC; the impact toughness is 17 to 20 J / cm2; furthermore, the spheroidal graphite ausferrite cast iron grinding ball is higher in processing hardening capacity; in a wear process, a worn layer is processed to be hardened, so that the hardness can be up to 62 to 64 HRC, and the wear amount is 70 percent of that of a general forged ball.

The invention discloses steel for a wear-resistant steel ball and a rolling machining method of the wear-resistant steel ball, and belongs to the technical field of spherical steel product machining.The steel for the wear-resistant steel ball is characterized in that the wear-resistant steel ball comprises the following primary chemical components of, by mass percent, 0.70-0.78% of carbon, 0.15-0.35% of silicon, 0.80-0.90% of manganese, less than or equal to 0.03% of phosphorus, less than or equal to 0.03% of sulfur, 0.5-0.6% of chromium, less than or equal to 0.25% of nickel and less than orequal to 0.25% of copper. The rolling machining method comprises the technological steps of treatment in a rotary furnace, LF refining, VD refining, continuous casting, straightening, acid pickling,neutralization, rolling, quench tempering, packaging and warehousing, and thus the wear-resistant steel ball is obtained. The production efficiency of the wear-resistant steel ball manufactured by rolling is high and the quality of the wear-resistant steel ball is high; a rolling technology is carried out by a tandem mill, so that the labor intensity of workers is reduced, and the labor environment is improved; and the overall process is automatically controlled, so that the hardness of the wear-resistant steel ball is uniform, the core hardness is high, the percentage of damage is low, and the impact value of the wear-resistant steel ball is high.

The invention discloses an all-position flux-cored wire for alkaline gas protection, which has both strong impact toughness and strong crack resistance and is suitable for protection of gas such as CO2 or CO2+Ar. The flux-cored wire is manufactured by drawing SPCC (steel plate cold commercial) steel strips or similar mild-carbon steel strips wrapping flux core in specific component proportion. By adopting an alkaline slag system, weld metal can be purified, hydrogen and oxygen contents of the weld metal can be reduced, so that excellent impact toughness and cracking resistance can be obtained. Desulphuration capacity of the alkaline slag system is utilized so as to further purify the weld metal and improve the cracking resistance.

The invention relates to a high-tenacity wear-resisting overlaying alloy welding wire for a cold-rolling support roller, and the overlaying alloy welding wire provided by the invention has excellent tenacity and suitable hardness. The alloy welding wire comprises the following chemical components by weight percent: 0.2-0.4% of C, 1.0-2.0% of Mn, 0.5-1.5% of Si, 3.0-6.0% of Cr, 0.5-2.0% of Mo, 1.0-3.0% of Ni, less than or equal to 0.02% of P, less than or equal to 0.01% of S, and impurities, wherein the impurities comprise mineral substances and alloy powder; the mineral substances, the content of which is 2-5%, comprises one or more than one of CaF2, CaCO3, Na3SiF6 and LiF2; the alloy powder, the total content of which is 0.3-2.0%, comprises one or more than one of vanadium, tungsten, niobium, titanium, aluminum, and the like; and 0.1-0.5% of rare earth is additionally added. The welding wire is matched with a suitable welding process, thereby acquiring the hardness of HRC (Rockwell hardness) 48-53. A low-carbon steel belt is used for wrapping the alloy powder and the mineral substances and then rolling and drawing are performed, thereby forming the welding wire. A reasonable component design is matched with HJ107, grains are refined and sulfur-removing components are added, so that the high-tenacity wear-resisting overlaying alloy welding wire is free from hot crack in an overlaying process, has the hardness and tenacity suitable for cold-rolling rollers, and meets the demand of overlaying a cold roller.

The invention discloses a heat treatment technology of an ultra-long mandrel used for a mandrel pipe mill, wherein the heat treatment characteristics of hot-work mould steel are considered according to the spot environment, the ultra-long mandrel adopts 4Cr5MoSiV1 steel (H13) as raw material, and the raw material is processed through forging, alignment, rough lathing with outside round surface and ultrasonic detection in turn and then is processed through heat treatment on a medium-frequency induction heating furnace. The heat treatment technology comprises the following steps: performing medium-frequency quenching once and tertiary medium-frequency tempering treatment three times. The beneficial effects of the medium-frequency heat treatment technology of the ultra-long mandrel are as follows: the technology is simple, the operation is convenient, the speed is fast, the oxidation and decarburization phenomenons are less, the material is saved; alignment is not needed to perform after the heat treatment, the production cost is low, the efficiency is high; the heating is uniform, the temperature difference on the surface of the mandrel is small, the temperature control accuracy is high, the four-quadrant hardness of the surface and the subsurface are uniform, the impact value can be increased by 10%, the cracking phenomena of the mandrel is delayed in use, the service life of the mandrel can be increased to twice of the common mandrel; and the technology is also applicable to the heat treatment of common floating mandrels and retained mandrels; and the energy consumption is low and pollution can not be caused to the environment.

The invention discloses a low-alloy medium-silicon vermicular graphite cast iron glass mold material and a preparation method thereof. The low-alloy medium-silicon vermicular graphite cast iron glassmold material comprises, by mass, 87.5-92.12% of iron, 2.8-2.89% of silicon, 3.4-3.6% of carbon, 0.4-0.5% of manganese, 0.2-0.29% of chromium, 0.1-0.15% of vanadium, 0.08-0.1% of titanium, 0.4-0.5% ofnucleating agent and 0.5-0.6% of vermiculizer. Through the optimized formula, the oxidation resistance and wear resistance of a mold are greatly improved. Meanwhile, through the mutual cooperative effect of the added materials, the toughness, oxidation resistance and wear resistance of the glass mold are greatly improved. Thus, the service life of the mold is prolonged.

The invention discloses a hardening and tempering method for a 12Cr13 stainless steel bar and aims to provide a method which guarantees the mechanical properties, also lowers the production cost and improves the production efficiency. The hardening and tempering method disclosed by the invention is characterized in that a thermal treatment process for hardening and tempering is optimized, namely an incomplete annealing pretreatment process is added before hardening and tempering, subsequently a desk type furnace / a continuous heating furnace is used for carrying out (hardening + tempering) hardening and tempering, straightening and stress relief annealing, wherein the 0-DEG-C impact value of the bar after straightening and stress relief annealing is not large in change; and finally the mechanical properties of the 12Cr13 bar totally meet the standard requirements of nuclear power materials. By using the hardening and tempering method disclosed by the invention, even a traditional heating furnace is adopted for carrying out hardening and tempering treatment on the bar, the mechanical properties can still meet the requirements of the standard nuclear power hardened and tempered 12Cr13, especially the o-DEG-C impact value is quite large in increment range and the numerical value fluctuates stably; after thermal treatment, the deviation of the hardness (HBW) of the overall bar is not larger than 15; the thermal treatment cost is lowered; and the production efficiency is improved.

The invention relates to a production method for a plastic mold steel refined cast ingot low in sulfur, phosphorus and inclusion content. The production method comprises the following steps that a rawmaterial is subjected to production smelting through an electric furnace (EBT furnace), molten steel is obtained; the molten steel is refined through a refining furnace, and refined molten steel is obtained; the refined molten steel is processed through a vacuum degassing furnace, and molten steel subjected to vacuum degassing is obtained; argon blowing treatment is conducted on the molten steelsubjected to vacuum degassing, and molten steel subjected to argon blowing is obtained; and special mold casting is conducted on the molten steel subjected to argon blowing, and the steel ingot whichis low in hydrogen and nitrogen content and of which the solidification structure and component segregation are effectively controlled. According to the production method for the plastic mold steel, the large-size plastic mold steel which is high in purity and low in sulfur and phosphorus content can be produced, and the inclusion content and the contents of impurity elements including sulfur andphosphorus are effectively controlled.

The invention provides abrasion-proof sheet metal and a preparation method thereof, and relate to the technical field of production of abrasion-proof materials. The abrasion-proof sheet metal is prepared from the following components in percentage:1.9-3.1% of C, 0.4-0.6% of Si, 0.2-0.8% of Mn, 0.2-0.6% of Mu,11.5-13.5% of Cr, S which is smaller than or equal to 0.10%, P which is smaller than or equal to 0.10%, 0.5-1.5% of Mo, 0.05-0.15% of V, 0.1-1.0% of Ti, 0.3-1.0% of Cu, and the balance being Fe. The preparation method comprises the following steps of melting raw materials; performing constant-temperature pouring; performing heat treatment, heating the sheet metal shaped through pouring for 3-5 hours at the temperature of 700-720 DEG C, performing warming until the temperature is 800-900 DEG C, performing quenching in quenching oil for 7-10 minutes at the temperature of 90-100 DEG C, and then performing tempering for 6-10 hours at the temperature of 300-350 DEG C; and performing heat treatment once again, putting the sheet metal obtained after the heat treatment in high-temperature-resistant silicone oil for soaking for 3-5 hours, fishing out the sheet metal, and removing external silicone oil. The abrasion-proof sheet metal disclosed by the invention is impact-resistant, long in service life, and good in abrasion resistance, so that the abrasion-proof sheet metal can be used in serious environment, and can resist strong corrosion and ultrahigh temperature.

The invention discloses a hardening and tempering method in pump body manufacturing, and belongs to the technical field of pump body machining and manufacturing. The method comprises the processes of normalizing, hardening, primary high-temperature tempering, secondary high-temperature tempering and medium-temperature tempering, namely two-time high-temperature tempering and once medium-temperature tempering are performed after hardening. Simultaneously, sodium nitrate, sodium nitrate and potassium nitrate serve as a medium, namely a mixed solution consisting of 25 weight percent of the sodium nitrate, 20 weight percent of the sodium nitrite, 20 weight percent of the potassium nitrate and 35 weight percent of water, so as to improve the hardenability of a product, and simultaneously reduce a surface pulling stress to be crucially effective in stopping hardening cracks. The method of the invention effectively improves an impact value of a pump body at the temperature of -40 DEG C and the mechanical property of the pump body, has high safety in a hardening and tempering processes, improves working environment and reduces the labor intensity of production staff.

The invention discloses a high-toughness steel plate used in an extremely cold environment. The high-toughness steel plate comprises the following chemical elements in percentage by mass: 0.05-0.16% of C; 0.60%-1.2% of Si; 0.40% to 1.20% of Mn; 0.30% to 1.00% of Cr; 0.40% to 1.00% of Ni; 0.01% to 0.10% of Ti; 0% to 0.60% of Mo; 0.30% to 0.80% of Cu; 0.01% to 0.06% of Al; 0.003%-0.06% of Nb, 0%-0.08% of V and the balance Fe and other inevitable impurities. In addition, the invention also discloses a manufacturing method of the high-toughness steel plate, which comprises the following steps: (1)smelting and casting; (2) heating; (3) rolling; and (4) quenching and tempering. The high-toughness steel plate has the characteristics of high strength, high toughness, excellent weldability, good surface quality and stable whole plate performance.

The invention discloses a biopsy forcep head and a preparation method thereof. The biopsy forcep head comprises carbon, chromium, molybdenum, manganese, niobium, copper, silicon and iron. The preparation method includes the steps that alloy powder particles are prepared; the alloy powder particles and an organic matter binder are mixed to prepare feed; the feed is formed into a forcep head green body on an injection forming machine; the binder in the forcep head green body is removed to obtain a degreasing green body; and the degreasing green body of the forcep head is sintered, insulated andcooled and then the biopsy forcep head can be obtained. The material density of the forcep head prepared through the method is larger than 96%, the hardness is not lower than 480HV0.2, the tensile strength is not lower than 1000MPa, the impact value is higher than 10J / cm<2>, the dimensional accuracy of the product is + / -0.2%, and a neutral salt spray test is carried out for over 20h. Moreover, nonickel composition harmful to human bodies is contained in the forcep head material. By means of the biopsy forcep head and the preparation method thereof, high-efficiency and low-cost production of the biopsy forcep head can be achieved.

The invention provides an efficient grinding ball special for an environment-friendly mill of a cement plant and a manufacturing method of the efficient grinding ball and relates to the technical field of wear-resistant material production. The efficient grinding ball is characterized by comprising 1.9% to 3.1% of C, 0.3% to 0.9% of Si, 0.2% to 0.8% of Mn, 11.5% to 13.5% of Cr, not larger than 0.10% of S, not larger than 0.10% of P, 0.5% to 1.5% of Mo, 0.05% to 0.15% of V, 0.1% to 1.0% of Ti, 0.3% to 1.0% of Cu and the balance Fe. The method includes the following steps that firstly, raw materials are smelted at the temperature from 1490 DEG C to 1550 DEG C; secondly, constant-temperature casting is performed at the temperature from 1440 DEG C to 1500 DEG C; and thirdly, thermal treatment is performed, wherein the raw materials are heated at the temperature from 700 DEG C to 720 DEG C for 7 hours to 10 hours, the temperature is increased to 960 DEG C to 990 DEG C, and the raw materials are quenched for 7 minutes to 15 minutes in quenching oil at the temperature from 110 DEG C to 145 DEG C and annealed for 8 hours to 10 hours at the temperature from 330 DEG C to 380 DEG C. The efficient grinding ball is resistant to impact, long in service life and good in abrasion resistance, so that the efficient grinding ball adapts to the severe ball-milling working condition environment, and the HRC ranges from 60 to 65; the impact value is larger than or equal to 6.5 J / cm<2>; the fallen ball impact fatigue service life is larger than 40000 times; and strong corrosion and ultra-high temperature are resisted.

Provided is a prehardened steel material containing: 0.05≤C≤0.25 mass %, 0.01≤Si≤1.00 mass %, 0.40≤Mn≤1.80 mass %, 0.0002≤S≤0.3000 mass %, 0.30≤Cu≤1.80 mass %, 2.00≤Ni≤3.90 mass %, 0.05≤Cr≤3.20 mass %, 0.05≤Mo≤0.80 mass %, and 0.30≤Al≤1.50 mass %, with a balance being Fe and unavoidable impurities, in which the prehardened steel material has: a cross-sectional size of 350 mm or more in width and 350 mm or more in height, a hardness of 34 to 43 HRC, an average value of prior austenite grain size being 85 μm or less, and an average value of impact value being 18 J / cm2 or higher.

The invention discloses an automobile connection rod and a thermal treatment process thereof. The automobile connection rod comprises a body, wherein the body adopts a cylindrical structure; a circular-hole-shaped wound type spring structure is formed in the middle of the outer ring of the body; the thermal treatment process comprises the following steps of quenching the automobile connection rod and tempering the automobile connection rod under medium temperature, wherein carbonitride with trace alloy elements is added to steel in order to develop high-intensity spring steel, austenite crystals can be thinned in the thermal treatment process, and a deposition enhancement effect can be achieved; and finally performing annealing. By the adding of the carbonitride with the trace alloy elements, the automobile connection rod is high in elasticity limit and yield ratio, high in toughness and high in surface quality.

The invention discloses steel for a wear-resistant steel ball and a rolling machining method of the wear-resistant steel ball, and belongs to the technical field of spherical steel product machining.The steel for the wear-resistant steel ball is characterized in that the wear-resistant steel ball comprises the following primary chemical components of, by mass percent, 0.70-0.78% of carbon, 0.15-0.35% of silicon, 0.80-0.90% of manganese, less than or equal to 0.03% of phosphorus, less than or equal to 0.03% of sulfur, 0.5-0.6% of chromium, less than or equal to 0.25% of nickel and less than orequal to 0.25% of copper. The rolling machining method comprises the technological steps of treatment in a rotary furnace, LF refining, VD refining, continuous casting, straightening, acid pickling,neutralization, rolling, quench tempering, packaging and warehousing, and thus the wear-resistant steel ball is obtained. The production efficiency of the wear-resistant steel ball manufactured by rolling is high and the quality of the wear-resistant steel ball is high; a rolling technology is carried out by a tandem mill, so that the labor intensity of workers is reduced, and the labor environment is improved; and the overall process is automatically controlled, so that the hardness of the wear-resistant steel ball is uniform, the core hardness is high, the percentage of damage is low, and the impact value of the wear-resistant steel ball is high.

The present invention relates to a manufacture method of polycrystalline diamond bit for geological prospecting. Said invention adopts a casting-forming process, and includes the following steps: using graphite as raw material to make bit master pattern, firstly using wax material and making the wax material into bit pattern, covering said bit pattern with several layers of fireproof coating material, then using graphite to make pattern shell, melting said pattern to obtain bit hollow pattern, melting the bit mixture, pouring to obtain bit casting and making the bit casting undergo the processes of surface quenching and thermal refining treatment so as to obtain the invented finished product. It is characterized by that the described bit mixture composition includes (by wt%) 80%-85% of 40CrMnMo alloy steel, 10%-14% of Cu and 3.5%-5.5% of Sn.

The invention belongs to the technical field of welding rod preparation, and discloses a heat-resistant steel hand welding rod for ultra-supercritical CB2 steel and a preparation method thereof. The heat-resistant steel hand welding rod is composed of a special H08Cr9MoV alloy core wire (produced by Jiangsu Yonggang Group Co., Ltd.) with low content of impurities such as phosphorus and sulfur and a coating wrapping the surface of the special H08Cr9MoV alloy core wire. The main components of cladding metal are 9% of Cr, 1.5% of Mo, 1% of Co, 1% of Ni and 0.2% of V, and meanwhile, trace alloy elements such as Nb, N and B are added, so that the weld joint deposited metal has good mechanical properties, especially impact energy performance after heat treatment, and the impact energy is larger than or equal to 47J in a normal temperature state. The tensile strength of the deposited metal and a welding joint is 630-750MPa under the heat treatment condition of 730-740 DEG C and time of 12h. According to the hand welding rod manufactured by the method, electric arcs are stable in the welding process, splashing is small, welding slag is uniform in covering, slag removal is good, weld joint forming is attractive, all-position welding can be carried out, and the welding process performance is good.

The invention discloses a metal flux-cored wire containing Ti and B for carbon dioxide gas shielded welding. The metal flux-cored wire is suitable for backing welding of thick plates and high-speed flat fillet welding of high film thickness primer steel plates. According to the metal flux-cored wire, the weight of metal cored powder accounts for 10-30% of the total weight of the flux-cored wire, wherein a steel tape sheath comprises, by total weight percentage, 0.001-0.025% of C, 0.001-0.030% of Si, 0.01-0.35% of Mn, 0.001-0.030% of Al, 0.001-0.020% of P, 0.001-0.020% of S and the balance Fe; the metal cored powder comprises, by total weight percentage, 0.1-5.0% of fluoride, 0.01-0.5% of C, 8-20% of Mn, 2-8% of Si, 0.1-5.0% of Ti, 0.01-0.1% of B, 0.01-2.0% of Zr and the balance Fe. The metal flux-cored wire is less in splashing quantity and can achieve crack resistance the same as that of a solid welding wire when backing welding is carried out on the thick plates, excellent gas porosity resistance can be achieved when high-speed flat fillet welding is conducted on the primer steel plates coated with high film thicknesses of 30-40 microns, and deposited metal has good mechanical properties.

The invention discloses a pile main bolt manufacturing technique of a million kilowatt grade nuclear power station. The manufacturing technique includes material-selecting, melting, heating, forging, cooling, after-forging heat treatment, defect-detecting, and forging capability heat treating. When selecting the material, the microelement content of the materials is controlled, the heat preserving duration in the intermediate temperature stage is prolonged, the heat raising and the heat preserving duration in the high temperature stage are reduced, the distortion volume in the course of the forging is controlled between 30 percent and 70 percent, the forging rate reaches 5 above; after-forging heat treatment, ultrasonic defect detecting, and forging capacity heat treating are conducted when the forging is finished. The main bolt produced according to the manufacturing technique of the invention can improve the impact value under the circumstance that the intensity keeps unchanged, theproduct can meet the RCC-M standard requirements completely, and the reliability and the safety of the pile pressure container using the main bolt of the million kilowatt grade nuclear power station can be ensured.

The invention relates to a nitrogen-increasing manganese-increasing method for high-strength steel production. The method comprises the following steps: feeding manganese nitride core-spun yarns into molten steel for increasing nitrogen and manganese in an LF furnace refining process, wherein the diameter of the manganese nitride core-spun yarns is 12-14mm, the core powder weight of the manganese nitride core-spun yarns is 450-500g / m, and the tare weight is 125-175g / m; feeding 280-300 meters of manganese nitride core-spun yarns into the molten steel per ton, realizing complete nitrogen increase, stably controlling the nitrogen increase of the molten steel to be 50-60ppm, and finishing partial manganese increase in the process of realizing complete nitrogen increase, wherein the manganese increase amount is 0.09-0.10 percent. According to the method, nitrogen is not needed to be blown in each process, the nitrogen increase amount is controlled in one step, the increase of nitrogen in the molten steel can be finished when the manganese is increased at the refining part, and the yield of nitrogen in the molten steel is improved.