108 results about "Cold formed" patented technology

The invention discloses a production method of high-toughness NM450 wear-resistant steel. The steel comprises the following chemical components in percentage by weight: 0.19%-0.20% of C, 0.25%-0.45% of Si, 1.10%-1.20% of Mn, less than or equal to 0.010% of P, less than or equal to 0.002% of S, 0.65%-0.70% of Cr, 0.020%-0.025% of Nb, 0.014%-0.020% of Ti, 0.070%-0.090% of Alt, 0.0014%-0.0020% of B, less than or equal to 0.00015% of H, less than or equal to 0.0045% of N, less than or equal to 0.0015% of O and the balance of Fe and inevitable impurities. The process comprises the steps of converter smelting, LF refining, VD vacuum degassing, continuous casting, heating, rolling and heat treatment, the thickness of the produced NM450 wear-resistant steel plate ranges from 6 mm to 25 mm, the surface hardness ranges from 420 HBW to 480 HBW, the yield strength is larger than or equal to 1200 MPa, the tensile strength is larger than or equal to 1400 MPa, the elongation is larger than or equal to 14%, the requirement for 6a diameter 90-degree cold bending is met, the impact Akv at the temperature of-20 DEG C is larger than or equal to 60 J, the impact Akv at the temperature of-40 DEG C is larger than or equal to 40 J, the toughness performance is matched, the bending cold forming performance is excellent, and the welding performance is good.

The application discloses a high cold formability austenitic stainless steel cold-rolled plate and a production method thereof, and solves the technical problem of poor cold formability of the austenitic stainless steel cold-rolled plate. The high cold formability austenitic stainless steel cold-rolled plate comprises the following components in percentage by mass: C: 0.035-0.045%, Si: 0.25-0.3%, Mn: 2-3%, Cr: 14-14.5%, Ni: 9-9.5%, N: 0.17-0.20%, Cu: 1.3-1.6%, Mo: 0.5-0.7%, and the rest is Fe and inevitable impurity elements. The production method of the high cold formability austenitic stainless steel cold-rolled plate comprises smelting, refining, slab continuous casting, cold rolling, heat treatment and coiling. The application can improve the cold forming performance of the cold-rolled plate, and meanwhile, guarantees that the microstructure performance of the cold-rolled plate is stable after forming.

According to the NM450 wear-resistant steel suitable for the polar working condition and the production method thereof, low-cost component design is adopted, and the process steps comprise smelting, refining, continuous casting, heating, rolling and heat treatment; the steel-making process and harmful elements are strictly controlled to improve the purity of molten steel so as to improve the internal quality of the steel plate, and a strict rolling, quenching and low-temperature tempering heat treatment process is adopted. The NM450 wear-resistant steel plate which is high in toughness adaptability, high in wear resistance and excellent in cold forming performance comprehensive performance is developed, the thickness ranges from 6 mm to 30 mm, the surface hardness ranges from 450 HBW to 480 HBW, the core hardness ranges from 440 HBW to 465 HBW, and the core hardness reaches 95% or above of the surface hardness; the yield strength is not less than 1200 MPa, the tensile strength is not less than 1400 MPa, and the elongation is not less than 13%; the impact AKV at-50 DEG C is greater than or equal to 60J, and the impact AKV at-60 DEG C is greater than or equal to 40J; the bending angle is 90 degrees, the bending diameter D is 6a, and the cold bending result is intact.

The utility model belongs to the field of single crystal furnace manufacturing, particularly relates to a high-strength cold forming composite end socket for a single crystal furnace, and aims to solve the problems that the conventional end socket for the single crystal furnace is difficult to simultaneously meet the requirements of high temperature resistance, high pressure resistance and mechanical strength, a furnace body and the end socket are inconvenient to align when the end socket is mounted, and the cost is high. In order to solve the problem that the welding position of the end socket is not accurate due to the fact that the welding position of the end socket is not accurate, the utility model provides the following scheme that the end socket comprises an end socket body, a plurality of connecting lugs which are uniformly distributed are welded on the circumference of the end socket body, and chamfers are arranged on the sides, close to the end socket body, of the connecting lugs. The sealing head body is made of various materials and used for installing and positioning the sealing head body, so that the sealing head body is more convenient and faster to install, the sealing head body not only has excellent high-temperature resistance and corrosion resistance, but also has the characteristics of high strength, high toughness, wear resistance and oxidation resistance, the service life of the sealing head is greatly prolonged, and the safety of the sealing head is greatly improved.

This invention discloses a method and apparatus for preparing metal ingots based on melt flow-limited stacking casting and rapid cooling forming, relating to the field of metal forming technology. This method is based on continuous or intermittent advancement of melt flow-limited bottom casting, layer-by-layer reciprocating stacking, and layer-by-layer relay rapid cooling forming. It can achieve continuous rapid cooling forming of the molten metal, refining grains, and by limiting atomic diffusion, achieve layer-by-layer freezing-type rapid solidification forming with uniform atomic distribution in the molten metal, reducing component segregation. It can also simultaneously achieve the relay upward movement or reduction of casting defects such as shrinkage cavities and porosity layer by layer. The flow-limiting guide nozzle is equipped with a liquid outlet and a parallel and similarly shaped anti-oxidation coolant spray nozzle, located at the bottom of a crucible with a filter to reduce inclusions. This invention can simultaneously and rapidly reduce and coordinately control defects such as coarse grains, shrinkage cavities, porosity, component segregation, and inclusions during the solidification of the molten metal in a short process, achieving short-process, high-quality manufacturing of metal ingots, especially large metal ingots (including amorphous ingots).

The invention discloses a method for preparing a clad plate strip by adopting a hot continuous rolling process and the clad plate strip. The method sequentially comprises the steps of plate blank heating, rough rolling, clad blank preparation, clad rolling, controlled cooling and coiling, wherein a plate blank is subjected to surface polishing after being subjected to rough rolling and dephosphorization, then is subjected to preliminary covering and welding with a to-be-covered plate strip to form a covering blank, and then enters a finishing mill group to be subjected to covering rolling; the surface polishing of the plate blank, the preliminary covering of the to-be-covered coil and the welding are all carried out in an atmosphere protection cover, and N2, CO2 or a mixed gas of N2 and CO2 is introduced into the atmosphere protection cover; the plate blank is made of carbon steel; and the plate strip to be covered comprises titanium, copper or stainless steel. According to the invention, the hot continuous rolling process is adopted to produce the clad plate strip on line, the clad plate strip integrates the excellent characteristics of corrosion resistance, electric conduction, heat dissipation and beauty of the clad layer and high strength of the substrate, and the cost is lower and the application range is wider to the greatest extent; the product has the characteristics of corrosion resistance, good heat dissipation performance, easiness in cold forming processing, attractive appearance and no coating.

The present invention relates to a 1100MPa grade high-strength tool steel wire rod and a manufacturing method thereof. The wire rod is designed with a chemical composition of medium carbon and Nb-V. The steel billet is rolled and spun into wire rod at a spinning temperature of 860°C or higher. The wire rod is then subjected to an online molten salt semi-quenching isothermal treatment. The wire rod is controlled to first undergo a front-end molten salt treatment so that the wire rod enters a bainite phase region from a high-temperature austenite state at a cooling rate of 30°C / s or higher, forming a structure mainly composed of quenched bainite. The wire rod is then subjected to a rear-end molten salt heating isothermal tempering and toughening stress relief treatment. Finally, the wire rod is slowly cooled on a roller to form a wire rod with a microstructure including tempered bainite and ferrite. The method can reduce material cost, effectively avoid martensitic brittle structure, control the microstructure of the hot-rolled wire rod, improve the plasticity and cold working performance of the wire rod, and achieve a product tensile strength of 980-1030MPa and a cross-sectional reduction rate of 61%-66%, so that the product can be directly processed into tool parts after cold forming.

This invention discloses an electric field-assisted spline cold forming method and machine tool; this invention belongs to the technical field of machining and metal plastic forming equipment; it aims to solve the problems of high load, rapid mold wear and poor forming quality in the cold forming of splines of difficult-to-deform materials such as high-strength alloy steel and titanium alloy; the positive terminal of the pulse power supply forms a circuit with the workpiece through the center and the negative terminal through the brush, so that the high-frequency pulse current flows directly through the cold forming deformation zone, inducing the electroplastic effect, reducing the yield strength of the material and improving plasticity; on this basis, the symmetrically arranged cold forming tools apply radial force to the workpiece as the spindle rotates, and the spline teeth are formed by the axial feed and rotation of the workpiece; this method deeply couples electric field softening with mechanical forming, fundamentally reducing the forming load, extending the mold life and improving the spline dimensional accuracy and surface quality.

This invention discloses a method for producing easily formable ultra-high strength steel plates for engineering machinery, belonging to the field of metal material processing technology. This invention employs a medium-carbon + multi-element microalloying system, and through converter steelmaking + refining, continuous casting, billet heating, two-stage controlled rolling, and quenching + tempering heat treatment, produces ultra-high strength steel plates with a thickness of 5-20 mm. The resulting steel plate has a matrix structure of ultra-fine-grained lath martensite with an effective grain boundary size of 1.2-1.5 μm, a yield strength ≥1500 MPa, a tensile strength ≥1800 MPa, an elongation >10%, an impact energy >50 J at -40℃, and meets the requirements of D=6a and 180° bending without cracking. It possesses ultra-high strength, excellent low-temperature toughness, and cold formability, and can be directly used for forming key load-bearing structural components of engineering machinery. The process is simple and highly adaptable to industrial applications.

The invention relates to a method for producing a cylindrical metal connector, wherein the connector comprises a tubular body with two internally hollow cylindrical areas joined by an intermediate area with a polygonal outer edge. The method is characterised in that the metal connector is produced from a single tubular metal element by means of a step of cold forming using a first tubular expansion tool intended to be in contact with the side wall of the tubular metal element, the first tool being provided with a section comprising a plurality of radially expandable segments shaped to provide the form of the polygonal intermediate section, each segment having a protruding edge. The segments are expanded by the action of a punch, such that, when the punch moves towards the first tool, as the punch is inserted into the first tool, the segments expand towards the side wall of the tubular body to be shaped, thereby forming the intermediate area with a polygonal edge.

The present disclosure relates to designing of steel composition for line pipe steel to be used for sour environment. The developed steel of the present disclosure exhibits enhanced tensile properties in accordance with API 5L PSL-2 specification for X-65 grade steel, along with superior hydrogen induced cracking resistance with crack length ratio (CLR) of less than 10%, crack thickness ratio (CTR) of less than 5%, crack sensitivity ratio (CSR) of less than 2%. The developed steel is designed such that it is readily hot / cold formed and welded to form linepipe tubes to be used for the transportation of natural gas or crude oil, especially of sour grade. The present disclosure also provide a method of manufacturing the said steel having the composition of the present disclosure.

The invention discloses a corrosion-resistant and high-performance aluminum alloy cable material as well as a preparation method and application thereof, and relates to the technical field of aluminum alloy preparation. The component formula of the conductor is Al-xMg-ySi-zNi-mCe-nSc-qY, x is larger than or equal to 0.05 and smaller than or equal to 0.3, y is larger than or equal to 0.6 and smaller than or equal to 1.4, z is smaller than or equal to 0.35, m is larger than or equal to 0.01 and smaller than or equal to 0.2, n is larger than or equal to 0.03 and smaller than or equal to 0.2, q is larger than or equal to 0.04 and smaller than or equal to 0.1, iron is a main impurity element in the alloy, and the content of the iron is not larger than 0.1%. The aluminum alloy cable material with excellent mechanical properties (the tensile strength is larger than or equal to 122 MPa, and the elongation is larger than or equal to 14%), electrical properties (the conductivity is larger than or equal to 62% IACS) and corrosion resistance (the maximum IGC depth is smaller than 100 micrometers) is prepared by adopting the technological method of flame direct injection smelting, synchronous water quenching pull casting, cold forming machining and non-isothermal aging synchronous heat treatment, and the aluminum alloy cable material is suitable for aluminum alloy cables. The method is short in technological process, good in cable quality, high in corrosion resistance and wide in application prospect.

This invention provides an electroslag welding apparatus and a welding method thereof. The electroslag welding apparatus includes a workpiece body and a power source. A slag pool is disposed within the workpiece body, and a molten pool is disposed below the slag pool. Metal slag in the slag pool accumulates below the molten pool after passing through it, forming a weld. A liquid-cooled forming slider is disposed around the periphery of the molten pool. The height of the molten pool increases with the accumulation of the weld, and the height of the liquid-cooled forming slider also increases with the molten pool. Furthermore, a first conductive path is provided between the slag pool and the positive electrode of the power source, a second conductive path is provided between the weld and the negative electrode of the power source, and a third conductive path is provided between the liquid-cooled forming slider and the negative electrode. The electroslag welding apparatus provided by this invention can solve the problem of poor weld formation quality in the prior art.

Steel flat product for cold forming consisting of a steel substrate coated with a protective coating, wherein the protective coating consists of an inner Al-Si-containing and an outer alkaline earth oxide and / or transition metal oxide-containing layer, and wherein the steel substrate has a composition containing (in wt.%): - up to 0.09 carbon - up to 0.3 silicon - up to 0.9 manganese - up to 0.025 phosphorus - up to 0.02 sulfur - up to 0.1 aluminum - up to 0.14% titanium and / or niobium - up to 0.001 boron, and possibly - further alloying elements selected from the group up to 0.01 N, up to 0.15 Cu, up to 0.15 Cr, up to 0.15 Ni, up to 0.025 Mo, and / or up to 0.05 Sn, and - Residual iron and unavoidable impurities.

The object of this invention is to provide a high-strength hot-rolled flat steel product and a method for producing such a flat steel product, thus achieving a combination of high strength with high local cold formability and high economy in terms of steel. This is achieved through a high-strength hot-rolled flat steel product with high local cold formability, having a tensile strength Rm of at least 760 MPa, a yield strength ratio of at least 0.8, and a porosity of at least 30%, advantageously at least 40%, particularly advantageously at least 50%, at least 10%, preferably at least 16%, an elongation at break of at least 0.12, advantageously at least 0.17, and a ratio of local cold formability to overall cold formability of at least 5 and at most 13, and a microstructure consisting of more than 50% (by volume) bainite, no more than 10% (by volume), advantageously no more than 5% (by volume) carbon-rich microstructure such as martensite, retained austenite, pearlite, etc. The steel has a ferrite-based microstructure and the following chemical composition (wt%): C: 0.04–0.08; Si: 0.1–0.6; Mn: 1.0–2.0; P: maximum 0.06; S: ​​maximum 0.01; N: maximum 0.012; Al: not more than 0.06; Ti: not more than 0.18 and / or Nb: not more than 0.08; Mo: not more than 0.35; Ti+Nb greater than 0.06, wherein carbon and nitrogen exist in excess of stoichiometry according to the following formula: 1.0 < (C / 12 + N / 14) / (Ti / 48 + Nb / 93 + Mo / 96), the remainder being iron, including unavoidable steel-related elements.

The invention discloses ultrahigh-strength steel for cold forming of automobiles, which contains Fe and inevitable impurities and further contains the following chemical elements in percentage by mass: 0.16-0.21% of C, 0.16-0.22% of Cr, 0.16-0.22% of Mo, 0.12-0.12% of Mo, 0.12-0.12% of Mo and the balance 0.5 to 1.0 percent of Si; mn: 1.7 to 2.4%; b: 0.001 to 0.004 percent of the total weight of the raw materials; 0.01 to 0.05 percent of Al; 0.045% to 0.085% of Ti; the microstructure of the steel plate comprises acicular bainite, retained austenite and precipitated carbonitride. The invention further discloses a manufacturing method of the ultrahigh-strength steel. The manufacturing method comprises the following steps: smelting and casting; hot rolling; pickling and cold rolling; and annealing. According to the ultrahigh-strength steel, through the design of relatively low alloy components, excellent mechanical strength and forming performance are obtained.

The invention relates to a method (100) for producing a one-piece vehicle wheel (1), wherein the vehicle wheel (1) has a wheel disc segment (2) and a wheel rim segment (3), and wherein the method (100) comprises: providing (101) a one-piece preform (4) of a metal material, in particular a circular blank (4) of a metal material or a strip (4) of a metal material, wherein the metal material is specified by material quality and / or material thickness; forming a cylinder (5) from the provided one-piece preform (4) of a metal material, wherein the cylinder (5) comprises the wheel disc segment (2) and the wheel rim segment (3); profiling (103) the respective material thickness in different regions of the respective segment (2, 3) of the wheel disc segment (2) and / or the wheel rim segment (3) of the one-piece vehicle wheel (1) based on a cold forming method, in particular based on a spinning forming method.

A system configured to roll metal into a foil. The system includes spaced apart working rolls to receive metal therebetween. The working roll is configured to press against the metal to roll the metal into a foil. A cooling subsystem is spaced apart from the working rolls on a working line configured to supply metal to the working rolls. The cooling subsystem is configured to cool the metal as it moves along the working line.

The invention relates to a preparation method of an NS3103 thousand-degree-grade heat-resistant element, and belongs to the field of material forming and processing. The preparation of the heat-resistant element is completed by using a ceramic auxiliary basic part to perform investment casting molding, heating the basic part, inserting the basic part into a plate in a heating state, and performing integral slow cooling molding. The preparation method specifically comprises the following steps: step 1, molding; 2, making a shell; step 3, roasting; step 4, smelting and pouring; and 5, cleaning and hot press molding are conducted. By improving the dimensional precision of the basic part and combining the hot press molding process, the problem that a large gap exists after a plate is inserted into the basic part is solved, and after batch production, the NS3103 thousand-degree-grade heat-resistant element matching part is compact and stable in production quality.

The present invention relates to a structural base course coating composed of one or more base layers, each base layer comprising, by mass relative to its total mass: - 50% to 90% asphalt aggregates comprising, by mass relative to its total mass, a residual bituminous binder content ranging from 3% to 8%; - 0% to 48% sand; - 2% to 10% hydraulic binder, characterized in that each base layer, after compaction, has a thickness strictly less than 15 cm and is free of added bituminous binder. The present invention also relates to a cold-forming process for said base course coating, as well as to a road surface. Figure for the abstract: no figure

The utility model discloses a high-barrier sewing forming packaging bag which comprises an upper film body and a lower film body, and the end edges of the upper film body and the lower film body are heat-sealed and encircled to form a bag body; the upper film body comprises an upper outer layer, an upper barrier layer and an upper functional layer which are sequentially arranged from the outside of the bag body to the inside of the bag body; the lower die body comprises a lower outer layer, a lower blocking layer, a lower inner layer and a lower functional layer which are sequentially arranged from the outside of the bag body to the inside of the bag body; and the upper functional layer and the lower functional layer are polyethylene films containing drying agents. The drying agent particles are mixed into the PE to form the upper functional layer and the lower functional layer, so that the validity period of the absorption instrument can be prolonged; the barrier layer is made of cold forming aluminum, so that a plane bag can be replaced by three-dimensional packaging, and high-barrier water and oxygen resistance can be realized; and the outer layer of the bag body adopts the nylon NY design, so that the puncture-resistant and wear-resistant effects of the packaging bag are improved.

The invention discloses a preparation method of thin-gauge 780MPa-grade hot-rolled automobile structure steel with complex cold forming capacity. The preparation method comprises the following steps: a steelmaking process; a hot rolling process; the steel comprises the following chemical components in percentage by mass: 0.04 to 0.06 percent of C, 0.03 to 0.10 percent of Si, 1.55 to 1.65 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.020 to 0.040 percent of Alt, 0.105 to 0.120 percent of Ti, 0.13 to 0.20 percent of Mo, 0.0020 to 0.0060 percent of N and the balance of iron element and inevitable impurities. The invention aims to provide the preparation method of the 780MPa-grade hot-rolled steel for the automobile structure, wherein the thickness of the 780MPa-grade hot-rolled steel is 2.0-6.0 mm, and the 780MPa-grade hot-rolled steel has excellent cold forming capacity, so that the complex forming requirements of part of automobile structural parts are met.

The invention discloses a hot-rolled copper-clad plate strip and a production method, the hot-rolled copper-clad plate strip comprises a steel substrate and a copper layer on at least one surface of the steel substrate, and a copper-steel transition layer is formed on a contact interface of the steel substrate and the copper layer; the steel substrate comprises the following chemical components in percentage by weight: 0.04-0.09% of C, less than or equal to 0.10% of Si, 0.25-0.45% of Mn, less than or equal to 0.018% of P, less than or equal to 0.008% of S, 0.01-0.04% of Al, less than or equal to 0.005% of N, 0.01-0.028% of Ti and the balance of Fe. And the balance of Fe and inevitable impurity elements. The high-strength and wide-specification requirements are met, the yield strength is larger than or equal to 355 MPa, the tensile strength is larger than or equal to 490 MPa, the ductility is larger than or equal to 30%, the width can reach 700-1800 mm, the good copper-steel interface bonding strength, surface quality and cold-bending machining characteristics are achieved, the cold-bending forming performance meets the 180-degree cold-bending requirements of D = 0a, and the cold-forming machining requirements of high-strength structural parts in the fields of heat dissipation, electric conduction, corrosion resistance and decoration are met; moreover, steel and copper are compounded in the conventional steel hot continuous rolling production process, acid pickling, splitting and annealing processes after copper-clad rolling in an existing copper-clad process are omitted, the production efficiency is higher, and the cost is lower.

The present invention relates to the field of steel production technology, and in particular to a wide bearing steel strip and a manufacturing method thereof. The method comprises: subjecting a continuous casting billet that meets the GCr15 steel composition requirements to heat treatment; subjecting the heat-treated continuous casting billet to hot rolling treatment to obtain an initial steel strip; the reduction amount of the continuous casting billet during the rough rolling process accounts for more than 70% of the total reduction amount of the continuous casting billet during the hot rolling process; during the rough rolling process, the single-pass reduction rate is 18-40%; the initial steel strip is cooled to a coiling temperature and then coiled to obtain a wide bearing steel strip; the width of the steel strip is 1000-1400 mm, the thickness is 3.6-10 mm, the cooling rate is 10-20°C / s, and the coiling temperature is 580-620°C. The wide bearing steel strip obtained by the method of the present invention has a more uniform structure, no network cementite in the structure, better plastic deformation performance, and is more suitable for cold forming such as stamping.

The invention discloses a production method for improving the cold forming performance of ultra-pure ferritic stainless steel, and belongs to the field of stainless steel production. The process sequentially comprises the steps of plate blank heating, rough rolling, finish rolling, coiling, thermal annealing and pickling, pre-rolling of a 20-roller mill, chrome steel wire shot blasting and pickling, rolling of the 20-roller mill, cold annealing and pickling, leveling of a temper mill, shearing and packaging. The method is characterized in that a composite rolling method of reciprocating rolling of the first two passes and the last two passes and one-way rolling of the middle pass is adopted in the cold rolling stage, and a roller sequence that a high-roughness F roller is used in the front section and a low-roughness H roller is used in the rear section is matched. By optimizing the hot rolling pass and the cold rolling process and cooperatively controlling the texture development, the strength of the favorable gamma fiber texture in the finished product is remarkably improved, the plastic strain ratio r value of the obtained 2D / 2B state cold-rolled steel coil is larger than 1.75, and the 2D / 2B state cold-rolled steel coil has excellent cold forming and deep drawing performance and can meet the high-end market requirement.

The invention discloses a 55Cr3 process method for a cold forming non-quenched and tempered automobile stabilizer bar. The 55Cr3 process method comprises the steps that a 55Cr3 blank produced through converter smelting, LF refining, RH vacuum treatment and a continuous casting route is sequentially subjected to heating, temperature control rolling and cooling. Aiming at the application requirements of the automobile stabilizer bar used in a cold forming and non-quenched and tempered state, the forming performance and the obdurability of the 55Cr3 are controlled, and the machining and application requirements of the stabilizer bar are met.

The invention relates to a novel manufacturing method comprising a cold forming process step for manufacturing an ammunition belt pin.

The present invention discloses a modular design method based on a CS-FC-SB combined wall. The modular design method includes decomposing the CS-FC-SB wall into a foamed concrete wall (CS-FC) with a cold-formed steel frame, an outer ecological straw board (SB), and end columns, and finally designing the connection method. The size, reinforcement, and foamed concrete model of the CS-FC are selected based on a performance-based design method, the thickness of the SB is obtained based on a finite element analysis method, the size of the end columns is constructed with reference to standard specifications, and the design of key parameters such as welding, self-tapping screws, or bolt connections is obtained based on a simplified calculation formula for the seismic requirements of the CS-FC-SB combined wall. The above modular design method can greatly simplify the calculation and analysis process of the CS-FC-SB combined wall. Only welding, self-tapping screws, and bolt connections need to be calculated on site, which can effectively shorten the construction period and reduce construction costs. It can be promoted and applied in low-rise and multi-story rural and town building structures.