40 results about "Invar alloy" patented technology

The invention relates to the technical field of strip rolling, and discloses a device for rolling an invar alloy ultra-thin strip by using a double-sided electrified auxiliary twenty-high rolling mill, which comprises a rolling mill, a double-sided electrified auxiliary twenty-high rolling mill, a double-sided electrified auxiliary twenty-high rolling mill, a double-sided electrified auxiliary twenty-high rolling mill, a double-sided electrified auxiliary twenty-high rolling mill and a double-sided electrified auxiliary twenty-high rolling mill, the electrifying resistance rollers are arranged on the left side and the right side of the rolling mill and connected with the upper surface or the lower surface of the strip, the electrifying resistance rollers are communicated with a power source, and the electrifying resistance rollers, the strip and the power source form a strip electrifying heating loop; a plurality of resistor elements are sequentially arranged in the electrified resistance roller in the length direction of the electrified resistance roller, the resistor elements are sequentially connected in series and connected with an external control center, the control center is used for controlling the resistance of the resistor elements, the electrified resistance roller is made of conductive materials, and the resistor elements are attached to the inner surface of the electrified resistance roller. The transverse temperature of the strip can be adjusted in a partitioned mode, and the problem of current instability is solved.

This invention discloses an Invar alloy steel ingot, its smelting method, and its applications, belonging to the field of alloy preparation technology. It solves the problems of low purity, large elemental segregation, numerous inclusions, and poor uniformity in existing Invar alloys. The composition of the Invar alloy steel ingot, by mass percentage, includes: Ni: 35.5%–36.5%, C ≤ 0.01%, Si: ≤ 0.05%, Mn: 0.30%–0.50%, Al: ≤ 0.02%, Mg: ≤ 0.05%, Zr: ≤ 0.05%, Ti: ≤ 0.05%, P: ≤ 0.005%, S: ≤ 0.001%, O: ≤ 0.0008%, N: ≤ 0.0005%, with the balance being Fe and other unavoidable impurities. The Invar alloy steel ingot of this invention has high purity, low impurity content, small elemental segregation, few inclusions, and good uniformity.

The application discloses a preparation method of large-size super-long invar alloy flat material, adopts four forging processes, and specifically comprises the following steps: first fire is used for head riser pretreatment, second fire is used for vertical ingot upsetting and octagonal shaping, third fire is used for secondary vertical ingot upsetting and multi-surface elongation, and fourth fire is used for finished product forging. Through segmented heating and forging cooperative control, the bottleneck problem existing in the forging process of the super-long specification is broken through, the large-size super-long invar alloy flat material with a weight of 25-30 t and a length of greater than or equal to 11 m is obtained, and the forging quality and production efficiency of the large-size super-long invar alloy flat material are significantly improved.

This invention discloses a bell-type annealing method for Invar alloy cold-rolled steel coils, comprising the following steps: S1, stacking Invar alloy cold-rolled steel coils in a bell-type annealing furnace, with metal heat transfer pads arranged between adjacent Invar alloy cold-rolled steel coils for isolation, the heat transfer pads having symmetrical groove structures; S2, during the bell-type annealing process, reducing sponge iron is placed in the bell-type annealing furnace, hydrogen is introduced, and the temperature is raised to 500-700℃ at a heating rate of 60-150℃ / h, then raised to 850-1000℃ at a heating rate of 20-50℃ / h and held for 20-40h, then cooled at a cooling rate of 20-40℃ / h, and removed from the furnace when the temperature inside the bell-type annealing furnace drops to less than 100℃; the flatness of the Invar alloy cold-rolled steel coils after bell-type annealing is ≤2.0mm / m. This invention can solve the problems of uneven stress release and easy oxidation of the edges due to uneven heating of Invar alloy strip.

The invention relates to a forecasting method suitable for deformation resistance in the invar alloy hot rolling process and application thereof, belongs to the field of hot rolling, and solves the problems that in the prior art, in the invar alloy hot rolling process, especially in the hot rolling and finish rolling process, deformation resistance forecasting is low in precision and large in deviation, and the plate shape and quality after hot rolling are difficult to guarantee. And a large amount of time and cost are required. The forecasting method comprises the following steps: collecting main equipment and process parameters of a hot rolling unit; invar alloy incoming material parameters and hot rolling process parameters are given; the outlet temperature of the jth pass is calculated; and determining the deformation resistance of the invar alloy in the jth pass. According to the method, accurate prediction of the deformation resistance in the invar alloy hot rolling process is achieved, and the accuracy error is small.

The invention discloses a method for preparing an ultra-high-purity invar alloy cast ingot based on forging diameter changing. The method comprises the following steps that firstly, a cast ingot is formed through vacuum electron beam melting; secondly, forging and diameter changing are conducted; according to the method, vacuum electron beam cold bed smelting, forging diameter changing and vacuum consumable remelting form a short continuous process, the prepared and formed invar alloy ingot has the advantages of being large in size, high in purity and grain size, uniform and compact in structure, few in defect and the like by optimizing parameters, and the short continuous process has the advantages of reducing the cost, improving the production efficiency and the like at the same time. And the efficiency is improved.

The present application relates to a kind of oil grinding agent suitable for ultra-thin invar alloy plate, pickling pretreatment method and pickling process, belong to the field of metal material surface treatment, at least one of the problems such as incomplete removal of existing direct pickling process, high risk of matrix overcorrosion, low pickling efficiency and poor surface quality uniformity is solved.One kind of oil grinding agent suitable for ultra-thin invar alloy plate, the oil grinding agent includes mineral oil and extreme pressure agent, the mass ratio of mineral oil and extreme pressure agent is (8-12):1.The present application realizes efficient stripping loose oxide layer, reduces pickling chemical burden, avoids matrix overcorrosion, improves overall efficiency, homogenizes initial surface state, and guarantees final treatment uniformity.

The application relates to the technical field of metal plate composite technology and discloses a preparation process of a Kovar alloy-copper composite plate, which comprises the following steps: a preparation process of an Invar alloy-copper composite plate, which comprises the following steps: s1, taking one Invar alloy plate and two copper plates; s2, immersing the Invar alloy plate into liquid copper after the Invar alloy plate is heated to 250-300 DEG C; s3, positioning the two copper plates and the Invar alloy plate to form a group of initial composite plate materials; s4, heating the whole in a heating furnace, the heating temperature is 700-850 DEG C, and the heating time is 20-40 min; s5, taking out and cooling to 500-650 DEG C, and then performing hot rolling; s6, performing stress relieving annealing on the composite blank; s7, naturally cooling to normal temperature after annealing, and cold rolling to form an Invar alloy-copper composite plate with a preset thickness. The Invar alloy-copper composite plate prepared through the process is more stable and not easy to separate between the plates, the composite plate has the physical properties of the Kovar alloy and good thermal conductivity.

The application discloses a kind of super-thick invar alloy plate of uniform organization and manufacturing method thereof, 6-9t invar alloy steel ingot is prepared by electric furnace→AOD refining→LF refining→VD refining→IC die casting process;Nb element is added in AOD refining process;After that, invar alloy steel ingot carries out stress relief annealing, and adopts three times upsetting and drawing process, upsetting reduction is according to the principle of increment, gradually refines steel ingot surface and heart grain structure, ensures that steel ingot internal organization is fully broken after recrystallization, then forged to target size after annealing, obtains invar alloy plate of thickness ≥50mm after air cooling;The application can prevent the grain coarsening of the heart of super-thick invar alloy plate with thickness greater than 50mm, and obtain super-thick invar alloy plate with grain size ≥4 levels and uniform organization.

This invention discloses a Fe-Ni-Co-Cr-V-Nb-C-N multi-component Invar alloy and its preparation method. The alloy exhibits stable low expansion characteristics under different heat treatment conditions. In atomic percentage, the alloy is composed of the following chemical components: Fe 53-57%, Ni 21-24%, Co 15-17%, Cr 4-6%, V 0.1-1.0%, Nb 0.05-0.3%, C 0.4-1.0%, and N 0.05-0.3%. This invention yields a series of Fe-Ni-Co-Cr-V-Nb-C-N Invar multi-component alloys with significantly improved strength, solving the problem of low strength in traditional Invar alloys and further expanding the application range of Invar alloys in load-bearing environments.

The invention relates to the technical field of batteries, in particular to a battery. The battery comprises a shell and an electrode assembly, wherein the shell comprises a first through hole and a second through hole; the battery further comprises a pole structure and a pressure relief device, the pressure relief device comprises a sealing piece, a first connecting piece and an acting piece, the sealing piece covers the first through hole, the acting piece is located on the side, away from the first through hole, of the sealing piece, the first connecting piece is connected with the sealing piece and the side wall of the shell, and the first connecting piece and the acting piece are arranged in a spaced mode in the first direction; the acting piece is made of at least one of a bimetallic strip, memory alloy and invar alloy; the battery comprises an electrolyte, the electrolyte comprises fluorocarboxylic ester, and the mass content of the fluorocarboxylic ester is 5-70% based on the mass of the electrolyte. The pressure relief device of the battery not only can play a role in sealing and waterproofing when the battery is normally used, but also can play a role in timely exhausting and pressure relief when the battery is in a high-temperature environment.

The present application relates to a kind of carbon fiber wing main force C type long beam manufacturing method, comprising: S1. the Invar alloy steel with small thermal expansion coefficient is selected, and forming mould is made by five-axis numerical control milling equipment;S2. carbon fiber woven fabric prepreg and carbon fiber unidirectional tape prepreg of medium temperature system are alternately laid and stacked on the forming mould of S1, and the wing long beam of entire C type structure is made;S3. the wing long beam of S2 laying and stacking is bagged, and is cured into shape in curing oven.Through the method, the problem of manufacturing difficulty of full composite wing main force C type long beam is solved, and by using carbon fiber woven fabric prepreg and carbon fiber unidirectional tape prepreg of medium temperature system, the face profile of curing and forming long beam and the deformation amount of effective control are guaranteed by using Invar alloy steel with little deformation with temperature variation, the quality of long beam is improved, and the energy consumption cost of the same temperature hot press tank process is reduced.

The invention discloses a power blade invar alloy forming mold preparation method and a forming mold, the forming mold comprises a suction surface forming mold, and the suction surface forming mold preparation method comprises the steps that invar alloy is adopted to prepare a main body frame of the suction surface forming mold; invar alloy is adopted as a skin panel, and the skin panel is heated and then pressurized and shaped; the shaped skin panel is welded with the main body frame; and the welded blank body is subjected to heat treatment to eliminate internal stress generated in the welding process. An invar alloy metal plate is adopted for shaping, a molded surface and a back frame are welded and formed, the size of the invar alloy is kept stable in a high-temperature environment due to the low thermal expansion coefficient of invar alloy, and the manufacturing method is particularly suitable for manufacturing large power blades. After welding is completed, internal stress generated in the welding process is eliminated through heat treatment, the overall strength and stability of the die are enhanced, the service life is prolonged, the reliability is improved, the power blade bearing high loads is not prone to deformation during forming, and the product quality is improved.

The invention belongs to the field of metal materials, and mainly relates to an ultralow-expansion invar alloy for the low-temperature field and a preparation method of the ultralow-expansion invar alloy. The Fe-Ni-based invar alloy composition system is subjected to composition optimization, the Ni element content in the alloy is reduced, a proper amount of Co element is added, it is guaranteed that the Ms point temperature of the alloy is lower than the service temperature of 260 DEG C below zero, and it is guaranteed that martensite phase transformation does not occur to the alloy at the service temperature of 260 DEG C below zero. And meanwhile, the Nb alloy element is added into the alloy, so that the grain boundary binding force of the as-cast structure of the steel ingot is strengthened, and the hot working plasticity of the large-specification steel ingot is further improved. Wherein the Nb element content is required to meet 0.01 (wt%) + 0.1% < = Nb (wt%) < = 0.03 (wt%) + 0.1%, and meanwhile, the first fire forging starting temperature of the alloy is required to be lower than 1050 DEG C, so that secondary carbide NbC is separated out during steel ingot forging, and the grain boundary binding force of a steel ingot as-cast structure is further improved.

This application provides an electropolishing method for Invar alloy substrates, specifically tailored to the surface characteristics of Invar alloy substrates thinned by ferric chloride reduction. The method involves using the Invar alloy substrate to be treated as the anode and a pure lead plate as the cathode, simultaneously immersing both the anode and cathode in an electrolytic tank containing an electrolyte for electropolishing. The electrolyte comprises phosphoric acid, sulfuric acid, malic acid, ethylene glycol, sodium dodecylbenzenesulfonate, and deionized water in a volume ratio of 6:1:1:1:0.5:0.5. Electropolishing the Invar alloy substrate thinned by ferric chloride using the above electrolyte composition and ratio yields an Invar alloy substrate with excellent surface quality. After polishing, the surface gloss of the Invar alloy substrate is increased to ≥92 GU, exhibiting a uniform and bright mirror-like effect.

The invention provides an invar alloy with an ultralow expansion coefficient and a precision machining method thereof.The invar alloy is composed of 35.9%-36.3% of Ni, 0.08%-0.12% of Ti, 0.02%-0.04% of Al, 0.003%-0.008% of B and the balance Fe, double VIP + VAR ultra-high-purity smelting, large-deformation multi-directional forging + solid solution structure refining, unique low-temperature stepped aging stabilization, liquid nitrogen ultra-precision cutting and low-heat input laser welding are combined, and the ultra-low expansion coefficient invar alloy is obtained. The invar alloy with ultralow expansion coefficient and high purity is prepared, and the problems of coarse grains and abrupt performance change of a welding area are effectively solved.

This application relates to the field of diamond tool manufacturing technology, and discloses a heat-fatigue-resistant ceramic tile diamond saw blade and its preparation process. The heat-fatigue-resistant ceramic tile diamond saw blade includes a base steel disc and a diamond cutting head welded to its outer edge. The cutting head is made of a mixture comprising: a base matrix powder consisting of 40-50 parts of pre-alloyed copper-nickel alloy powder, 25-35 parts of elemental iron powder, 8-12 parts of elemental cobalt powder, and 13-17 parts of elemental tin powder; 5-10% Invar alloy powder, 1-3% elemental molybdenum powder, and 0.5-1.0% titanium hydride powder added according to the total weight of the base powder; and uncoated single-crystal diamond particles accounting for 15-25% of the total volume of the sintered cutting head. This invention uses a technical solution of pre-alloyed copper-nickel alloy powder combined with Invar alloy powder to adjust the matrix expansion rate, achieving the technical effect of reducing the alternating stress at the interface between diamond and metal binder.

The invention relates to the technical field of gas detection, in particular to a CTE self-adaptive adjustment detector and application. The CTE self-adaptive adjustment detector sequentially comprises a high-temperature-resistant optical fiber unit, a detector base, an aspheric optical fiber collimator, a detector shell, a reflecting mirror support, a reflecting mirror and an elastic body in the light path direction. The reflector is made of fused quartz, the support is made of invar alloy, and the elastic body is designed to be an annular sheet, located between the reflector and the support and bonded through the high-temperature-resistant cementing layer. Through the synergistic effect of the elastomer and the high-temperature-resistant cementing layer, axial and radial thermal stress generated in a high-temperature environment due to the difference of thermal expansion coefficients of materials is dynamically released and compensated. According to the invention, the problems of reflector rupture, optical path offset, zero drift and the like caused by CTE mismatch of a traditional detector in a high-temperature environment of 300 DEG C are solved, and the long-term stability, the measurement precision and the maintenance-free operation capability of the detector in extreme high-temperature environments such as a main steam pipeline of a nuclear power station and the like are remarkably improved.

The invention relates to the technical field of metal refining, in particular to an electroslag remelting process intelligent regulation and control method for invar alloy preparation, which comprises the following steps: acquiring current data and historical data; acquiring a basic power decline curve based on historical data; acquiring a pause section and a non-pause section according to the basic power decline curve; the degree that a temperature change rate curve of the cooling water gradually approaches 0, the degree that an electrode weight change rate curve gradually approaches 0 and the balance degree of input and output at the temperature measuring point are obtained through the current data corresponding to the pause section and the non-pause section; according to the degree that the temperature change rate curve of the cooling water gradually approaches to 0, the degree that the weight change rate curve of the electrode gradually approaches to 0 and the balance degree of input and output at the temperature measuring point, the matching degree of heat output and heat input is obtained; and adjusting the power decline rate based on the matching degree of the heat output and the heat input. According to the invention, accurate control and adjustment of the electroslag remelting process can be realized.

The invention provides a dynamic component posture and position monitoring device for beam yard hoisting operation, and belongs to the technical field of precise instruments and thermal management. The dynamic component posture and position monitoring device is characterized in that an invar alloy inner ring is connected with a pre-embedded steel disc in a concrete base; the brass middle ring is coaxially nested on the outer surface of the invar alloy inner ring; the composite material outer ring coaxially coats the outer side of the brass middle ring; the heat exchange flow channel is filled with a vaporized heat-conducting medium, and the vaporized heat-conducting medium is converted from a liquid state to a vapor state after absorbing heat and moves from an evaporation end to a condensation end; the temperature-sensitive driving piece is connected with the condensation end of the heat exchange flow channel, and the length is changed according to the temperature of the condensation end. A rotating shaft of the displacement lever is arranged on the top surface of the invar alloy inner ring; the temperature-sensitive driving piece is connected with a power arm of the displacement lever; a guide rail is arranged on the bottom side of the top of the shell platform, the resisting arm end of the displacement lever slides along the guide rail to drive the shell platform to move in the vertical direction, and thermal expansion errors are counteracted. According to the invention, the ultra-high stability of the measurement basis is realized through a multi-cooperation mechanism.

The present application relates to invar smelting technical field, a kind of smelting invar process method, comprising the following steps: step one: iron-nickel alloy raw material is loaded into intermediate frequency furnace, intermediate frequency furnace tapping temperature: 1590±20 ℃, intermediate frequency furnace ton steel power consumption 520±30 Kwh / t;Step two: after melting in intermediate frequency furnace, it is poured into AOD and smelted;Step three: after completing oxygen blowing and removing P in AOD, it is carried out to discharge slag;Step four: after AOD discharges slag, it is carried out to adjust composition, molten steel deoxidation;Step five: LF is carried out to adjust composition, temperature, and molten steel is processed into LF station.The present application is the first low-cost smelting invar process method in domestic, under the premise of guaranteeing product quality, can not use pure nickel resource and utilize more economical iron-nickel alloy raw material to produce the invar of component meeting the requirements, realizes the full use of iron-nickel alloy resources, greatly reduces invar production cost.

This invention relates to the field of precision alloy material processing technology, and discloses an Invar alloy precision strip for semiconductor displays, its preparation method, and applications. This invention controls sulfur content at the source and combines this with microalloying by adding 0.002–0.005 wt.% rare earth cerium (Ce) to strengthen grain boundaries and improve thermoplasticity. It innovatively employs an ultra-high purity smelting route of "vacuum induction melting (VIM) + two vacuum arc remelting (double VAR)" combined with intermediate forging to remove non-metallic inclusions such as oxides and reduce gas content, obtaining ultra-high purity ingots. Finally, through a multi-stage high-temperature diffusion forging, controlled rolling and cooling, multi-stage intermediate annealing, and precision cold rolling, a precision strip with a thickness of 0.10 mm is prepared. Through the above process, the strip prepared by this invention has extremely high purity, a uniform and fine microstructure (grain size 8–10), and excellent surface quality and shape, fully meeting the stringent requirements of semiconductor display devices for substrates.

This invention belongs to the field of solid-state hydrogen storage technology, and in particular, a constrained structure for a solid-state hydrogen storage device. It includes a bimetallic structure disposed within a hydrogen storage container. The bimetallic structure is composed of two metals or alloys with significantly different coefficients of thermal expansion. The bimetallic structure includes an active layer and a passive layer. The active layer includes at least one of brass, nickel-copper, and nickel-chromium alloys, while the passive layer includes at least one of Invar alloy, iron-nickel alloy, and stainless steel. When the temperature rises, the bimetallic structure bends towards the passive layer side; when the temperature drops to its original state, the bimetallic structure returns to its original shape. This invention offsets some of the stress experienced by the hydrogen storage tank during hydrogen absorption, extends the service life of the hydrogen storage module, prevents powder pulverization and migration, optimizes the hydrogen storage performance of the hydrogen storage tank, balances uneven hydrogen absorption and temperature distribution within the hydrogen storage tank, and improves overall hydrogen storage performance.

This invention discloses an Invar alloy slab and its preparation method, belonging to the field of alloy preparation technology. It solves the problems of existing Invar alloy slabs having numerous inclusions, significant segregation, and being prone to cracking, overheating, coarse grains, and poor uniformity during forging. The method includes: preparing an Invar alloy consumable ingot; the mass percentage of O in the consumable ingot is less than 0.0007%, the mass percentage of N is less than 0.0004%, and the consumable ingot is free of general segregation, ingot shape segregation, and general porosity defects; homogenizing the consumable ingot with a multi-stage heating and holding process; and forging the slab after homogenization annealing to obtain a final forging temperature ≥900℃. The preparation method of this invention ensures that the forging process does not crack or overheat, and the prepared Invar alloy slab has fine and uniform grains.

The invention discloses a method and system for evaluating the grain size of an invar alloy forge piece, and the method comprises the following steps: S1, designing heat treatment process parameters based on differential thermal analysis data of an invar alloy and a precipitated phase evolution rule obtained by a scanning electron microscope, and preparing invar alloy samples with different grain sizes; s2, detecting by an ultrasonic longitudinal wave vertical incidence method, and extracting a frequency domain characteristic value of an ultrasonic signal; s3, the microstructure morphology of the invar alloy sample is obtained, and a twin crystal feature recognition strategy is established in combination with the precipitated phase morphology; s4, obtaining an influence rule of microstructure change of the invar alloy sample in a tissue evolution process on the frequency domain characteristic value, and researching a mapping rule between an ultrasonic signal and a defect depth; and S5, constructing an ultrasonic time-frequency domain multi-feature fusion evaluation model for the grain size and the macroscopic defect of the invar alloy. The method solves the problem that an existing linear model with a single ultrasonic parameter is difficult to accurately characterize the grain size change of the invar alloy.

The invention discloses a preparation method of a large ultra-long invar alloy flat material, which adopts a four-heating-number forging process, and specifically comprises the following steps: carrying out head riser pretreatment in a first fire, carrying out vertical ingot upsetting and octagonal shaping in a second fire, carrying out secondary vertical ingot upsetting and multi-surface drawing out in a third fire, and carrying out finished product forging in a fourth fire. Through cooperative control of segmented heating and forging, the bottleneck problem existing in the ultra-long specification forging process is solved, the large ultra-long invar alloy flat material with the weight reaching 25-30 t and the length larger than or equal to 11 m is obtained, and the forging quality and production efficiency of the large ultra-long invar alloy flat material are remarkably improved.

The invention discloses an invar alloy and a preparation method thereof, belongs to the technical field of invar alloys, and solves the problem that the mechanical strength, the low expansion characteristic and the corrosion resistance of the invar alloy cannot be improved at the same time in the prior art. The invar alloy comprises the following components in percentage by mass: 35.0%-37.0% of Ni, less than or equal to 0.03% of C, less than or equal to 0.30% of Si, 0.20%-0.60% of Mn, 0.10%-0.30% of Zr, 0.01%-0.03% of Ce and the balance of Fe and inevitable impurities. The invar alloy is excellent in comprehensive performance.

The invention discloses an invar alloy plate strip with an ultralow expansion coefficient and a production process thereof, and relates to the technical field of material science, the invar alloy plate strip comprises less than or equal to 0.05% of C, less than or equal to 0.10% of Si, less than or equal to 0.40% of Mn, 3.5-4.5% of Co, 0.038-0.042% of Al, 32.0-34.5% of Ni, 0.40-0.45% of Nb and the balance of Al. The invar alloy melt comprises the following components in percentage by weight: less than or equal to 0.020% of P, less than or equal to 0.020% of S, less than or equal to 0.0015% of O, less than or equal to 0.0010% of N, less than or equal to 0.0002% of H and the balance of By optimizing alloy components, particularly adjusting the contents of niobium, cobalt, nickel and carbon, a stable ultralow expansion coefficient in a temperature range of 20-100 DEG C is realized, so that the stability of the invar alloy in a temperature change environment is improved, and the application range of the invar alloy in the field with high precision requirements is expanded; and the dimensional stability and the shape precision can be kept for a long time.

The invention discloses an invar alloy cold-rolled strip with excellent welding performance and a production method thereof. The invar alloy cold-rolled strip comprises the following chemical components in percentage by weight: 0.02-0.06% of C, less than or equal to 0.40% of Si, 0.20-0.60% of Mn, less than or equal to 0.008% of P, less than or equal to 0.003% of S, 34.8-37.5% of Ni, 0.01-0.08% of Nb, 0.005-0.02% of Al, 0.0001-0.003% of Ca and the balance of Fe and inevitable impurities, and the total amount of the inevitable impurities is less than 0.05%. The linear expansion coefficient of the invar alloy cold-rolled strip at the temperature of-180 DEG C to 0 DEG C is (1.0-2.0) * 10 <-6 > / DEG C. According to the method, the thermal crack resistance tendency of the invar alloy can be improved, so that hot cracks are not prone to being generated on metal after welding, and it is ensured that the invar alloy cold-rolled strip has excellent welding performance.

The invention provides an invar alloy plate and a surface control method thereof. The surface control method of the invar alloy plate comprises the following steps: a thinning step: a first working roller is matched with rolling oil with first kinematic viscosity to carry out at least two passes of rolling on an incoming material to obtain a thinned plate, and the rolling oil between the first working roller and the incoming material forms an oil film with first thickness in the rolling process; and a leveling step, specifically, a second working roller is adopted to be matched with rolling oil with second kinematic viscosity to conduct at least one pass of rolling on the thinned plate, in the rolling process, the rolling oil between the second working roller and the thinned plate forms an oil film with second thickness, and the oil film with the second thickness extrudes the surface of the thinned plate to form a plurality of oil pits, and obtaining the invar alloy plate. According to the embodiment of the invention, the oil pits obtained through oil film extrusion are small in plane area and shallow in depth, and the AOI defect detection rate in the subsequent precision metal mask manufacturing process can be reduced.