226results about How to "Improve pitting resistance" patented technology

A flux-cored nickel-based alloy wire contains, based on the total mass of the wire, 3 to 11 percent by mass of TiO₂, 0.2 to 1.3 percent by mass of SiO₂, 1 to 3 percent by mass of ZrO₂, and 0.3 to 1.0 percent by mass of manganese oxides in terms of MnO₂, contains of a total of 0.2 to 1.0 percent by mass in terms of Na, K and Li of sodium compounds, potassium compounds, and lithium compounds. The flux has a ratio (([TiO₂]+[ZrO₂])/[SiO₂]) of the total of the TiO₂ and ZrO₂ contents to the SiO₂ content of 5.0 to 14.5, in which [TiO₂], [SiO₂] and [ZrO₂] represent TiO₂, SiO₂ and ZrO₂ contents. The wire shows excellent weldability in welding of all positions typically on 9% nickel steels and nickel-based alloy steels and gives a weld metal having good pitting resistance, bead appearance, and resistance to hot cracking.

An aluminum alloy clad sheet for heat exchangers includes a core layer, a sacrificial layer disposed on one side of the core layer, and a brazing layer of an Al—Si alloy disposed on the other side of the core layer, wherein the core layer contains Si: 0.15% to 1.6% by mass, Mn: 0.3% to 2.0% by mass, Cu: 0.1% to 1.0% by mass, Ti: 0.02% to 0.30% by mass, and the remainder of Al and incidental impurities, and the sacrificial layer contains Zn: 4.0% to 10.0% by mass, Cr: 0.01% to 0.5% by mass, and the remainder of Al and incidental impurities.

The invention relates to duplex stainless steel. The duplex stainless steel comprises the following chemical components in percent by weight: 0.01-0.08% of C, 0.2-1.0% of Si, 1.5-3.5% of Mn, 19.0-21.0% of Cr, 1.2-2.8% of Ni, 0.08-0.18% of N, less than or equal to 0.5% of Mo, less than or equal to 1.0% of W, less than or equal to 1.0% of Cu and the balance of Fe and inevitable impurities; PREN (Pitting Resistance Equivalent Number) is 20-24, the martensitic temperature Md formed by strain induction is 60-130 DEG C. A manufacturing method comprises the following steps of: selecting vacuum induction smelting in an electric furnace, argon oxygen decarburization (AOD) or electric furnace, argon oxygen decarburization (AOD), external refining and LF (Ladle Furnace) smelting; carrying out die casting or continuous casting on molten steel, controlling the superheat degree to be 20-50 DEG C in die casting, matching with fast cooling, preventing nitrogen from escaping, and controlling the overheat degree to be 20-50 DEG C and the plate blank casting speed to be 0.8-2m/min; and putting a die-casting blank or a continuous casting blank into a heating furnace for heating to 1100-1250 DEG C, preserving the heat for 0.5-1.5 hours, processing the die-casting blank or the continuous casting blank on a forging production line or a hot-rolling mill group to the needed thickness, then carrying out annealing at the speed of 0.5-2.5min/mm and the temperature of 1030-1150 DEG C. The obtained duplex stainless steel has excellent corrosion resistance and TRIP effect.

The invention relates to an austenitic stainless steel medium-thick plate which comprises the following components in percentage by weight: no more than 0.04 percent of C, 0.3-0.9 percent of Si, 1-2 percent of Mn, no more than 0.010 percent of S, no more than 0.04 percent of P, 16-22 percent of Cr, 8-14 percent of Ni, no more than 4 percent of Mo, 0.04-0.30 percent of N, 0.0010-0.0030 percent of B, smaller than 0.30 percent of one or more rare-earth elements, such as Ce, Dy, Y and Nd, 1-10 percent of high-temperature ferrite delta and the balance of ferrum and unavoidable impurities. The manufacture method of the austenitic stainless steel medium-thick plate comprises the following steps of: smelting; hot rolling; heating and preserving the temperature of the alloy and then carrying out 4-10 passes of rolling in a recrystallization area at 1,250-1,050 DEG C; water-cooling the recrystallization area by 20-40 DEG C/s to 700-950 DEG C, rolling 3-5 rounds in the temperature interval and water-cooling to room temperature; carrying out low-temperature annealing heat treatment at 900-1,050 DEG C; washing with acid and then obtaining the austenitic stainless steel medium-thick plate with excellent strength.

A duplex stainless steel containing C, Si, Mn, P, S, Al, Ni, Cr, Mo, N (nitrogen, O (oxygen), Ca, Mg, Cu, B, and W, and the balance Fe and impurities, where a number of oxide-based inclusions, which have a total content of Ca and Mg of 20 to 40% by mass and also have a long diameter of not less than 7 μm, is not more than a 10 per 1 mm² of the cross section perpendicular to the working direction, or further, the number of oxide-based inclusions, which have a content of S of not less than 15% by mass and also have a long diameter of not less than 1 μm, is not more than 10 per 0.1 mm² of the cross section perpendicular to the working direction. Particularly, the contents of Cu, B and W are desirably 0.2 to 2%, 0.001 to 0.01%, and 0.1 to 4% by mass, respectively.

A steel plate of the invention contains C: 0.03-0.2%, Si: 0.05-0.5%, Mn: 0.4-1.8%, P: less than 0.04%, S: less than 0.040%, Al: 0.01-0.10%, N: 0.002-0.0080%, Cu: 0.1-0.5% and Ni:0.1-0.50%, at old austenite grain bound with depth 10 mu m away from the surface of the steel plate, an enrichment area having total content of Cu and Ni more than 1.2% is present, and the area rule of the enrichment area in the section of the plate thickness is more than 5%. According to the structure, even if painting dressing and electric protection are not implemented, practical pitting tolerance is excellent, which is exerted when applied in the crude oil storage tank.

The invention discloses abnormally segregated stanniferous low-clearance ferritic stainless steel and a preparation method thereof, and belongs to the technical field of metallurgy. The stainless steel comprises the following components in percentage by weight: 0.005-0.03% of C, 0.2-0.4% of Si, 0.2-0.5% of Mn, less than or equal to 0.03% of P, less than or equal to 0.02% of S, 14-16% of Cr, less than or equal to 0.01% of N, 0.1-0.4% of Sn, Nb, Ti and/or V and the balance of iron and inevitable impurities; the tensile strength is 445-451MPa; the pitting potential is 202-240mV. The preparation method comprises the following steps: (1) smelting and casting a blank according to set components; (2) heating to be 1150+/-10 DEG C, carrying out heat preservation for 1-3 hours, and subsequently hot-rolling to make a hot-rolled steel plate; (3) annealing at 900+/-10 DEG C for 2-3 hours, cooling to room temperature, pickling and then cold-rolling to make a cold-rolled steel plate; (4) heating to 800+/-10 DEG C and carrying out normalizing treatment to obtain the abnormally segregated stanniferous low-clearance ferritic stainless steel. By adopting the method disclosed by the invention, the production cost of the stainless steel can be greatly lowered, the process is simple, and a product is high in strength, hardness and corrosion resistance.

The invention discloses a duplex stainless steel with pitting corrosion resistance and favourable cold temperature flexibility and a manufacturing method thereof. The duplex stainless steel comprisesthe following components in mass percentage: 0.01-0.10% of C, 0.2-1.0% of Si, more than 0% and less than 1.5% of Mn, 20.0-22.0% of Cr, 1.8-4.0% of Ni, 0.08-0.2% of N, more than 0% and less than 0.5% of Mo, less than or equal to 1.0% of one or more than one of W and Cu and the balance Fe and inevitable impurities. The invention controls Mn content below 1.5% until zero and simultaneously adjusts the content of elements of N, Ni and the like to ensure that steel has high strength, favourable corrosion resistance and favourable impact toughness at room temperature and low temperature when steel contains no or small amount of noble element Mo; meanwhile, the duplex stainless steel has low cost and small hot working difficulty, can be largely applied in the fields of buildings along the coast,petrochemical industry and the like and can replace 304 austenitic stainless steel of which the nickel content is above 8% at room temperature and lower temperature.

The invention provides a duplex stainless steel thin strip and a near-net shaping preparation method thereof, and belongs to the technical field of steel alloy materials. The duplex stainless steel thin strip comprises, by mass, 0.0001%-0.03% of C, 18%-22% of Cr, 5%-7% of Mn, 0.3%-0.45% of N, 0.0001%-0.1% of Ni, and the balance iron and other inevitable impurities. The preparation method includes the steps that (1) smelting is carried out under nitrogen; (2) molten steel is guided out along with rotation of crystallizing rollers to form a cast strip, and the cast strip is cooled to the room temperature through water; (3) hot rolling is carried out for 1-2 passes, and the strip is cooled to the room temperature through water; (4) the hot-rolled stainless steel thin strip is subjected to acid pickling; (5) the stainless steel thin strip is cold-rolled; and (6) a finished product is obtained after solution annealing. The duplex stainless steel thin strip prepared through the method has a good corrosion property; the initial as-cast structure is refined, and a good property can be obtained in subsequent processing; according to the preparation method, segregation of elements is restrained, and the alloy elements can be distributed more evenly after subsequent rolling and solution annealing; cost is low, and the production process is simple and easy to operate.

The invention provides a method for a laser preparation of a titanium nitride gradient coating on a surface of titanium and titanium alloy. The method comprises the steps of performing surface cleaning treatment, surface blackening treatment and preheating treatment for a workpiece subatrate; and then carrying out laser nitriding treatment. The method is characterized in that the laser nitriding treatment is performed in a condition of filling reaction gas, and simultaneously laser scanning treatment and ultrasonic oscillating treatment for the surface of the workpiece subatrate are carried out. The titanium nitride gradient coating with a thickness of 50-200 [mu]m is obtained on the surface of the titanium and titanium alloy. The titanium nitride gradient coating is mainly composed of a nitride layer and a nitrogen diffusion layer, and has uniform transition of the coating microstructure. The surface hardness, wear resistance and corrosion resistance of the titanium nitride gradient coating are improved significantly than those of the matrix. Also, problems that crack are easy to produce, surface roughness is large, and the crystal grains of dendrite crystals of a nitride layer are coarse, in ordinary laser gas nitriding processes, are solved.

A nitrided steel member including an iron nitride compound layer formed on a surface of a steel member having predetermined components, wherein: in X-ray diffraction peak intensity IFe₄N (111) of a (111) crystal plane of Fe₄N and X-ray diffraction peak intensity IFe₃N (111) of a (111) crystal plane of Fe₃N, which are measured on a surface of the nitrided steel member by X-ray diffraction, an intensity ratio expressed by IFe₄N (111)/{IFe₄N (111)+IFe₃N (111)} is 0.5 or more; Vickers hardness of the iron nitride compound layer is 900 or less, Vickers hardness of a base metal immediately under the iron nitride compound layer is 700 or more, and a difference between the Vickers hardness of the iron nitride compound layer and the Vickers hardness of the base metal is 150 or less; and a thickness of the iron nitride compound layer is 2 to 17 μm.

The invention discloses a low-hydrogen type super duplex stainless steel welding rod. The prior duplex stainless steel wire is adopted as a welding core. The coating of the welding rod comprises the compositions in percentage by weight: 35 to 45 percent of marble, 20 to 33 percent of fluorite, 0 to 5 percent of titanium pigment, 2 to 5 percent of potassium feldspar, 0 to 2 percent of sodium carbonate, 5 to 15 percent of iron alloy, 10 to 20 percent of metal powder, and 0 to 2 percent of CrN iron, wherein the iron alloy consists of ferrosilicon and ferromolybdenum under the condition of constant total content, and the metal powder consists of manganese metal, chromium metal, and nickel powder under the condition of the constant total content. After raw materials of the compositions of the coating are mixed evenly, pure sodium water glass with certain Baume concentration is added, and the pressing of the welding rod is performed on welding rod production equipment. The use of the welding rod can satisfy the welding need of super duplex stainless steel in the national engineering construction, the welded welding seam has excellent mechanical property and good corrosion resistance, the tensile strength can reach 800MPa, and the welding rod has good low-temperature toughness.

Ferrite stainless steel comprises the following components in percentage by weight: less than or equal to 0.02 percent of C, 0.30 to 0.60 percent of Si, 0.20 to 0.40 percent of Mn, less than or equal to 0.01 percent of S, less than or equal to 0.05 percent of P, 1.60 to 18.0 percent of Cr, less than or equal to 0.02 percent of N, 0.4 to 1 percent of Mo, 0 to 0.06 percent of Nb, 0.05 to 0.25 percent of Ti and the balance of Fe and inevitable impurities, wherein Ti is more than or equal to 4*Nb. The method for manufacturing the ferrite stainless steel comprises the following steps: smelting by an electric furnace-AOD-VOD three-step method; performing casting, hot rolling, annealing and acid washing, cold rolling and annealing and acid washing processes; calculating theological precipitationtemperatures of M23C6, sigma phase and chi phase according to a Thermo-calc phase diagram and taking a maximum value x DEG C of the precipitation temperatures of three precipitated phases, wherein the hot rolling and annealing temperature is equal to the highest theological temperature x DEG C plus 50 to 100 DEG C, and the annealing time is between 2 and 4 minutes; and the cold rolling and annealing temperature is equal to the highest theological temperature x DEG C plus 100 to 150 DEG C, and the annealing time is between 1 and 3 minutes; and performing air cooling after annealing. Prepared Mo-containing ferrite stainless steel has excellent corrosion resistance and moldability, and can be widely applied in household appliance industry.

The invention relates to acid rain corrosion-resistant austenitic stainless steel and a manufacturing method thereof. The acid rain corrosion-resistant austenitic stainless steel comprises the chemical components in percentages by weight: 0.03-0.06% of C, 0.1-1.0% of Si, 5.0-7.0% of Mn, less than or equal to 0.06% of P, less than or equal to 0.01% of S, 16.0-17.0% of Cr, 2.0-3.0% of Ni, 1.0-1.5% of Mo, 2.5-3.5% of Cu, 0.15-0.25% of N, 0.1-0.3% of V, 0.05-0.5% of Sn, 0.001-0.005% of B and the balance of Fe and inevitable impurities, wherein the condition is satisfied as follows: (Cr+3.3Mo+16N) is greater than or equal to 22 but less than or equal to 26. A purpose of improving the capacity of resisting acid rain corrosion of the material is achieved with relatively low cost. The corrosion rate of the steel in a 5% diluted sulfuric acid is less than or equal to 30g/(m<2>.h), and the room temperature tensile strength is greater than or equal to 800MPa, and the steel can partially replace 304 stainless steel to use.

The invention relates to a MnCr carburized gear steel and its production method, the MnCr carburized gear steel comprises the following components by mass percentage: 0.25-0.30% of C, less than or equal to 0.12% of Si, 0.60-0.80% of Mn, 0.80-1.10% of Cr, less than or equal to 0.035% of P, 0.020-0.050% of S, 0.020-0.055% of Al, less than or equal to 20ppm of [O] and the balance of Fe and inevitable impurities. By using an electric furnace smelting, the end point [C] is 0.10-0.15%, [P] is less than or equal to 0.015%, [Si] is less than or equal to 0.05%, and the tapping temperature is 1630-1680DEG C. The method comprises the steps of LF refining, adjusting slag by using carbon powder; feeding aluminum line, calcium line and sulfur line; vacuum treating; soft blowing argon; continuously casting a blank, controlling the tundish temperature at 1520-1540 DEG C, and strictly controlling the casting speed according to different blank types. The isothermal temperature, heating time and rolling temperature can be strictly controlled during the rolling process; thereby a hot-rolled round steel is prepared.

The invention discloses a thermal treatment method used for improving a duplex stainless steel welded structure, which comprises the following steps: 1) heating by an electric oven at the temperature lower or close to duplex stainless steel phase transition when a duplex stainless steel weld seam and a heat affected zone are heated by a thermal treatment technology, simultaneously carrying out electric pulse heating; 2) insulating for 10-60 minutes after heating, cooling with three phases, wherein in a first phase, the temperature of the welded structure is 850 DEG C and the cooling speed is controlled at 1-30 DEG C/s, simultaneously providing pulse current; in a second phase: the temperature is decreased to 800-500 DEG C, the cooling speed is controlled at 5-50 DEG C/s, and the cooling speed is greater than that of the first phase; in a third phase: the temperature is decreased below 500 DEG C and the cooling speed is controlled more than 30 DEG C/s. The thermal treatment for duplex stainless steel welded seam and the heat affected zone can control the volume fraction and existence form of ferrite, avoid the precipitation of a brittleness phase in ferrite/austenite, ferrite/ferrite crystal boundary, and enhance the capability of pitting corrosion resistance of the duplex stainless steel.

The invention discloses a corrosion-resistant spring steel for high-speed railway spring bars and a production method thereof. The chemical composition and mass percentage of the corrosion-resistant spring steel are as follows: C: 0.50-0.60%, Si: 1.40-2.20%, Mn : 0.70~1.00%, Cr: 0.36~0.50%, Ni: 0.36~0.60%, Cu: 0.26~0.50%, P: 0.015~0.030%, S≤0.015%, and the balance is Fe and unavoidable impurity elements. The production method includes converter smelting, LF refining, VD vacuum degassing, continuous casting, continuous casting slab heating, and rolling processes; in the converter smelting process, the C content at the control end point is ≥0.08%, and the tapping temperature is controlled at 1640±30°C. The invention satisfies the requirements of the standard on the mechanical properties of the spring steel under the conventional production process conditions of the spring steel through proper component design. After the spring is made according to the existing high-speed railway spring production process, the corrosion resistance of the steel body is significantly improved, and it has broad application prospects.

The invention discloses precipitation-hardening martensitic stainless steel for a surgical operation and a heat treatment process thereof, and belongs to the technical field of stainless steel material. The stainless steel comprises the following chemical composition: not more than 0.07 wt% of C, not more than 1.00 wt% of Si, not more than 1.00 wt% of Mn, not more than 0.040 wt% of P, not more than 0.030 wt% of S, 3.00-5.00 wt% of Ni, 15.0-17.5 wt% of Cr, 3.5-5.5 wt% of Cu, 0.05-0.15 wt% of N, 0.15-0.45 wt% of Nb, and the balance Fe. After the stainless steel is subjected to special heat treatment, a copper-rich phase can be precipitated evenly and dispersedly in a stainless steel matrix, and thus the stainless steel is endowed with an antibacterial function. The stainless steel solves the problem of bacterial infection caused by the use of stainless steel tools in a conventional surgical operation, is widely applied in various stainless steel appliances such as scalpels, surgical scissors, surgical forceps, intestinal forceps and curettes used in the surgical operation in the medical clinical field.

The invention discloses a preparation method for graphene-316L stainless steel based on selective laser melting. The preparation method comprises the following steps that graphene powder and 316L powder are mixed to obtain 316L and graphene mixed powder; then, the mixed powder is subjected to selective laser melting block forming, the optimal technological parameters are obtained through analysisof density, mechanical properties, electrochemical corrosion and metallographic and microcosmic appearance, the exposure time is 100 microseconds, the dot pitch is 50 micrometers, the power is 210 W,the laser energy density is 49.35 J/mm < 3 >, and compared with pure 316L stainless steel, the graphene/316 L stainless steel sample under the optimal technological parameters has the advantages thatthe yield strength is improved by 28%, the tensile strength is improved by 26%, and the corrosion resistance is improved.

The invention relates to high-strength stainless steel, a heat treatment process and a forming member. The high-strength stainless steel is prepared from the following components according to weight percent: 0.2 to 0.35% of C, 0.7 to 3.50% of Mn, 0.6 to 2.0% of Si, 11 to 17% of Cr, less than or equal to 0.20% of Nb, less than or equal to 0.20% of Ti and the balance of Fe and impurities. The heat treatment process comprises the following steps of (a) heating the high-strength stainless steel to 1000 to 1200 DEG C, and then insulating for 1 to 3600 s; (b) cooling the high-strength stainless steel treated in the step (a) below 100 DEG C; and (c) heating the high-strength stainless steel treated in the step (b) to 150 to 400 DEG C, then insulating for 10 to 10000 s, and then cooling to room temperature in any cooling mode. The forming member is made of the high-strength stainless steel, and the microstructure of the forming member is composed of 5% to 30% of retained austenite, 70% to 95%of martensite, less than 1% of Nb and Ti carbide and less than 2% of Cr carbide in an area.

The invention provides a hot-dipping Zn-Al-Mg coating steel plate with an excellent dip plating performance, and a production method. A coating contains 1 to 5 percent of Al, 1 to 3 percent of Mg, less than or equal to 0.0104 percent of Fe, 0.1 to 1 percent of Si, 0.01 to 1 percent of Ce, and the balance Zn and inevitable impurities. Compared with the prior art, according to the hot-dipping Zn-Al-Mg coating steel plate with the excellent dip plating performance, and the production method provided by the invention, through designing the plating solution element content, adding 0.1 to 1 percentof Si and 0.01 to 1 percent of Ce, and controlling Al to be 1 to 5 percent, the infiltrating performance of a plating solution and a substrate is improved, and a large number of iron elements are prevented from being brought into zinc liquid so as to cause an adverse effect, so that the coating is uniform and fine in microstructure. The designed plating solution adapts to a steel plate for a common household appliance and has a good infiltrating effect on the surface of the steel plate; and in addition, through optimizing annealing and hot-dipping processes, the coating formed on the surface of the steel plate is fine and uniform in microstructure without skip plating or shrinking and is remarkably improved in pitting corrosion resistance.

The invention discloses low-cost austenitic stainless steel with excellent corrosion resistance, which comprises the following chemical elements in mass percentage: smaller than or equal to 0.04% of C, 16.00-19.00% of Cr, 8.00-10.00% of Ni, 0.50-1.50% of Mo, 2.10-4.50% of Cu, 0.02-0.08% of N, smaller than or equal to 0.80% of Mn, 1.30-2.50% of Si, smaller than or equal to 0.04% of P, smaller thanor equal to 0.005% of S, 0.0010-0.0040% of B and the balance of Fe and other inevitable impurities, and the ratio of Si to Mn is 2.5 to 4. The corrosion resistance and mechanical properties of the austenitic stainless steel are far better than those of 304L or approach or reach the level of 316L austenitic stainless steel, but the cost is lowered by 20-30% as compared with that of the 316L austenitic stainless steel.

The invention provides superaustenitic stainless steel and a preparing method thereof. The superaustenitic stainless steel is prepared in the following percent by weight: smaller than or equal to 0.020% of C, smaller than or equal to 1.00% of Si, smaller than or equal to 2.00% of Mn, smaller than or equal to 0.045% of P, smaller than or equal to 0.035% of S, smaller than or equal to 0.1% of N, 19.0-23.0% of Cr, 1.2-2.0% of Cu, 4.0-5.0% of Mo, 23.0-28.0% of Ni, smaller than or equal to 0.0050% of O, smaller than or equal to 0.010% of Al, smaller than or equal to 0.020% of Ca, smaller than or equal to 0.030% of B and the balance of Fe. The method adopts a protection process of smelting superaustenitic stainless steel mother liquid by adopting a Consteel electric furnace and an intermediate frequency furnace, AOD, LF and continuous casting of a sheet billet, and can smelt the high-Ni, high-Cr, high-Mo, Cu-containing and low-C superaustenitic stainless steel, and both the surface quality and internal quality of the continuous casting billet are good.