56 results about "Strain hardening exponent" patented technology

An in-reactor polymer blend comprises (a) a propylene-containing first polymer; and (b) an ethylene-containing second polymer such that the polymer blend comprises between about 50 wt % and about 80 wt % units derived from ethylene and between about 50 wt % and about 20 wt % units derived from propylene. The blend is substantially free of dienes and the content of ethylene in the second polymer in the form of ethylene-ethylene-ethylene triads is at least 40%. The second polymer contains at least 0.1 branch having 8 or more carbon atoms per 10,000 carbons. In addition, the blend has a strain hardening index of at least 1.8, a shear thinning slope in the plot of log(dynamic viscosity) versus log(frequency) of less than −0.2 and exhibits at least two peaks when subjected to Differential Scanning Calorimetry (first melt) corresponding to a first melting point of at least 150° C. and a second melting point of at least 40° C. such that the difference between the first and second melting temperatures is at least 20° C.

A measuring method for a real stress-strain curve of a metal welding structure comprises the steps: firstly, measuring a real stress-strain curve of a notch tensile test, wherein a real fracture strain at a maximum load is a strain hardening index of a metal of a to-be-measured position; calculating real stress-strain curves of notch tensile samples by finite element calculating software, to obtain the real stress-strain curves of the notch tensile samples with different notch sizes, fitting and establishing the relationship between the notch size and a geometric factor, and establishing a geometric factor expression containing the notch size and the real fracture strain at the maximum load and other influence factors; according to a load separation theory and the obtained relational expression and expression, the real stress-strain curve of the metal of the to-be-measured region of the metal welding structure is obtained. Through the small-size notch tensile test and a series of established relationships, the locality of the to-be-measured material region is accurately transmitted to a whole single-region material.

The invention discloses a method for measuring residual stress on surface of a metal sample based on micro indentation. The method comprises the following steps: performing a micro indentation test on the surface of the sample by utilizing a Vickers microhardness tester, recording the indentation morphology by adopting a scanning electron microscope, and obtaining the nominal projection area and actual projection area of the indentation on the surface of the sample through calculation for diagonal length and side length of the micro indentation; obtaining a strength coefficient and strain hardening index of the material through a standard tensile test; and obtaining a theoretical formula for measuring the residual stress through an indentation method and containing the ratio of the actual projection area to the nominal projection area of the micro indentation, the strength coefficient and strain hardening index based on the hypothesis for the two-dimension isometric residual stress field on the surface of the sample, and further obtaining the residual strain and residual stress on the surface of the sample. The measurement method belongs to basically nondestructive or micro-damage measurement and has the advantages of low measurement cost, simplicity and convenience in operation and high measurement efficiency. If being combined with a portable high-power optical microscope with a distance measurement function, the method can be popularized and applied in the field of engineering.

The invention discloses a device of measuring yield strength and a strain hardening exponent of a metal material by an indentation method. The device comprises a servo motor, a pressure propeller anda transverse plate that are sequentially connected from the top down, wherein the pressure propeller is internally provided with a pressure rod; the pressure rod is driven by the servo motor and penetrates through the transverse plate and a pressure sensor; a pressure rod bottom plate is arranged at the lower end of the pressure rod; the lower part of the pressure rod bottom plate is sequentiallyconnected with a pressure head base, a pressure head connecting rod and a pressure head; four corners of the transverse plate are connected with a magnetic pressure platform via side plates; the servomotor and the pressure sensor are connected with a computer; and the yield strength and the strain hardening exponent are calculated by a load-displacement curve. According to the device, the computer controls the motor to allow output displacement of the motor to be capable of accurately tracking and reproducing input displacement; nondestructive and micro-destructive measurement of a measured object to be detected are achieved; and mechanical properties of the metal material are characterized by the micro-load continuous indentation method by taking a load and depth in an indentation process as response values.

A technology for manufacturing a rolled and welded dual-layer tube used for the connection between indoor and outdoor units of air conditioner includes such steps as decoiling the copper plated steel band made of low-carbon non-gap atomic steel, spreading on rolling machine, rolling it by 720 deg. to become a dual-layer tube, soldering in NH3 gas, annealing in NH3 gas, cooling, spraying passivated water, and coiling.

The invention discloses a method for determining the maximum strain hardening exponent according to the strength of a steel-iron material. The method comprises the following steps of: I, deducing a formula among the yield strength, tensile strength and maximum strain hardening exponent of the steel-iron material; II, determining the yield strength and tensile strength of the steel-iron material to be detected; and III, calculating the maximum strain hardening exponent of the steel-iron material according to the formula deduced in the step I. The method has the characteristic of quick, convenient and accurate acquisition of the maximum strain hardening exponent according to the strength of the steel-iron material.

The present technology relates to a foam comprising a polypropylene material. The polypropylene material is produced in the presence of a metallocene catalyst, and the foam and/or the polypropylene has a branching index g′ of less than 1.00 and a strain hardening index (SHI@1 s⁻¹) of at least 0.30 measured by a deformation rate dε/dt of 1.00 s⁻¹ at a temperature of 180° C., where the strain hardening index (SHI) is defined as the slope of the logarithm to the basis 10 of the tensile stress growth function (log(η_E⁺)) as a function of the logarithm to the basis 10 of the Hencky strain (log(ε)) in the range of Hencky strains between 1 and 3.

A short-chain-branched polypropylene having xylene solubles of at least 0.5 percent by weight is provided. In certain embodiments the polypropylene has a strain hardening index of at least 0.15 as measured by a deformation rate of 1.00 s⁻¹ at a temperature of 180° C. In certain embodiments, the strain hardening index is defined as the slope of the logarithm to the basis 10 of the tensile stress growth function as function of the logarithm to the basis 10 of the Hencky strain for the range of the Hencky strains between 1 and 3. The polypropylene may have xylene solubles in the range of 0.5 to 1.5 percent by weight. In certain embodiments, the polypropylene has a strain hardening index in the range of 0.15 to 0.30. In certain embodiments, the polypropylene has a melting point of at least 148° C.

The invention discloses an instrumentation indentation test method for elastic-plastic parameters of a material based on a single Vickers pressure head. According to the method, the strain hardening exponent, elasticity modulus and offset yield strength sigma 0.2 of the metal material are determined by virtue of three instrumentation indentation load-depth curves in which indentation positions have special aggregation manners. The method has the advantages that the strain hardening exponent, elasticity modulus and offset yield strength sigma 0.2 of the metal material can be tested only by virtue of the single diamond Vickers pressure head; the high-precision test on the elasticity modulus of the material can be realized based on the tested strain hardening exponent of the material; the indentation positions of the three instrumentation indentation have aggregation properties, and the elastic-plastic parameters of the microcell material can be tested.

The invention discloses a strengthening-toughening treatment process for high-strength martensite/ferrite dual-phase steel, and the dual-phase steel. The dual-phase steel with fine crystalline grainsand a dual-phase structure of lamellar ferrite and lamellar lath martensite is finally obtained through a two-time forging process comprising high-temperature forging and medium-temperature forging, and a two-phase region quenching process, and by adopting a process of lamellar refining for replacing a traditional process of granular refining; the adverse effects on the plasticity due to the reduction of n value (strain hardening exponent) which is caused by the traditional granular refining are avoided, the lamellar refining for crystalline grains is realized, the effect of crystalline grainrefining is achieved, and strengthening-toughening treatment is completed; and the martensitic structure content in the dual-phase steel which is obtained through the treatment process is not lower than 40%, and compared with a sample treated by a common process, the tensile strength sigma b can be increased by more than 60%, and the plasticity can be increased by more than 70%, so that the strength and toughness of the martensite/ferrite dual-phase steel are remarkably improved.

The invention discloses an experimental method for building forming limit diagram of transformation induced plasticity steel plates, relating to the building method of forming limit diagrams. The method of the invention comprises the following steps: (1) the thickness and the strain hardening index of the transformation induced plasticity steel plate are determined; (2) the limit strain value of the transformation induced plasticity steel plate under the condition of plane strain state is calculated; (3) a strain coordinate system is built, data is synthesized on the coordinate system so as to build the forming limit diagram of the transformation induced plasticity steel plate. The invention is an effective tool for solving the transformation induced plasticity steel plate material punching problem, can successfully predict transformation induced plasticity steel plate material invalidation, effectively estimates the forming performance and reduces the existing measuring workload for building a shaping limit diagram.

The invention relates to an ultra-deep-draw Ti-IF steel cold rolling and annealing process. A steel plate blank comprises the following chemical components in percentage by weight: less than or equal to 0.005% of C, less than or equal to 0.2% of Mn, less than or equal to 0.01% of P, less than or equal to 0.008% of S, more than or equal to 0.015% of Alt, 0.04-0.064% of Ti, less than or equal to 0.006% of N and balance of Fe and microimpurities which can not be detected; five-pass cold rolling is adopted in a cold rolling process, and the total rolling reduction of the five-pass cold rolling is 75-85%; inlet rolling speed and outlet rolling speed are respectively 260KN and 29KN; and an anneal process comprises two-stage warming, wherein heating rates are respectively 70-85 DEG C/h and 30-45 DEG C/h, annealing temperature is 680-720 DEG C, holding time is 8-15 hours, then three-stage cooling is adopted, cooling rates are respectively 25-35 DEG C/h, 35-45 DEG C/h, 15-25 DEG C/h, and finally cooling to room temperature is carried out. The ultra-deep-draw Ti-IF steel cold rolling and annealing process provided by the invention has the advantages that the tensile strength after the process is carried out is up to 290-320MPa, the yield strength is 100-160MPa, the strain hardening index is more than or equal to 0.25, and the planar aeolotropy degree is less than or equal to 0.60.

The invention discloses strip steel with excellent performance at low temperature secondary processing and with tensile strength being 390 MPa. The steel comprises the following components of, by wt%,0.0008%-0.0028% of C, 0.07%-0.1% of Si, 0.5%-0.7% of Mn, 0.060%-0.075% of P, less than or equal to 0.008% of S, 0.02-0.05% of Al, 0.02%-0.06% of Ti, 0.006%-0.022% of Nb, 0.0005%-0.0015% of B, and less than or equal to 0.002% of N. The production steps comprise smelting and casting into a blank, cast blank heating, rough rolling, finish rolling, coiling, cold rolling after acid pickling, continuous annealing treatment, slow cooling, rapid cooling, aging treatment and flattening. According to the steel, under the premise of guaranteeing mechanical property, a plastic strain ratio is 1.6-1.8r<90>, a strain hardening index is 18-0.19n<90>, a brittle transition temperature of the secondary processing is stabilized at minus 60-minus 70 DEG C, the quantities of the elements Ti and the Nb are reduced, the cost is reduced by no less than 5%, the surface of a steel plate is free of carbonization edges and bonding defects, and the steel is used for an outer cover of an automobile in a more severe cold area.

The invention discloses a preparation method of a graphitized cold-rolled high-carbon steel plate for stamping forming, and belongs to the technical field of metallurgy. The preparation method is characterized in that besides conventional methods like smelting, continuous casting, hot rolling, acid pickling and cold rolling, technological processes like bainite treatment and graphitizing annealing are adopted, wherein the bainite treatment is adopted for providing a good preparation structure for the graphitizing annealing; isothermal transformation is carried out in a manner that isothermal treatment with the temperature being 30-50 DEG C above Ac3 is carried out and then rapid cooling to a lower bainite transition temperature range is carried out; and the graphitizing annealing mainly adopts the isothermal treatment with the temperature being 620 DEG C to Ac1. The steel plate prepared by the preparation method mainly consists of graphite and ferrite grains structurally, graphite particles are distributed uniformly, the mean diameter of the graphite particles is approximately 5 micrometers, and the mean diameter of the ferrite grains is approximately 20 micrometers. Due to such structural characteristics, the high-carbon steel plate has the same plasticity and softness as low-carbon steel, and thus has the good stamping forming property, a yield ratio of the high-carbon steel plate is less than or equal to 0.60, the strain hardening exponent is greater than or equal to 0.2, and the planar anisotropy is less than or equal to 0.20.

The invention relates to IF steel containing niobium and titanium for an advanced automobile and an annealing process, which belong to the technical field of metallurgy. The IF steel containing the niobium and the titanium for the advanced automobile and the annealing process are characterized in that continuous heating is adopted in the annealing procedure, the heating rate is 4 to 8 DEG C/minute, the annealing temperature is 700 to 750 DEG C, the heat-preservation time is 1 to 10 hours, and the material is cooled to 400 to 450 DEG C along with a furnace and is taken out of the furnace for air cooling. By the mode, IF steel with excellent deep drawability can be obtained; a test sample of the IF steel after being processed by the process has excellent deep drawability; in a longitudinal direction, the tensile strength reaches 290 to 330MPa, the yield strength is 125 to 155MPa, and the elongation rate is 40 to 55 percent; in a transverse direction, the tensile strength reaches 310 to 340MPa, the yield strength is 120 to 190MPa, and the elongation rate is 40 to 55 percent; and the plane anisotropy delta r of the strain hardening index is not greater than 0.25.

The present invention provides a production process of double wall brazed tube for connecting air-condition indoor and outdoor machine, putting a horizontally striping double-sided copperplating steel belt made from low-carbon gapless atomic steel on a uncoiling disk; coil rolling the copperplating steel belt at 720 degrees on forming machine to form double wall brazed tube canister; entering brazing furnace, and injecting decomposed protection gas NH3 in the furnace to solder; entering the double wall brazed tube after soldering to sealing cooling tube filled with decomposed protection gas NH3 to cool, and cooling slowly and cooling again; spraying and drying directly by passivation water; collecting to disk shape by winder and the disk shaped double wall brazed tube is obtained. The disk shaped double wall brazed tube is processed by off-line controllable atmosphere bright annealing and fixed length. The double wall brazed tube obtained by present invention has plastic strain ratio r >2.0, strain hardening index n >0.25, elongation delta >45%, yield strength delta s <150 Mp; when installing as air-condition connecting pipe, can realize manual molding in installing scene of air-condition connecting pipe, can't appear staved and cockled phenomenon of the tube wall, and reduces partial energy consume at the same time.

Disclosed is a steel plate with axial bearing capacity and excellent formability used for cans and a manufacturing method thereof. The steel plate comprises the following components, by weight: 0.020%-0.080% of C, no more than 0.030% of Si, 0.20%-1.00% of Mn, no more than 0.020% of P, 0.0020%-0.0080% of N, and Al, with the balance being Fe and unavoidable impurities, wherein 10<=Al/N<=20. High yield strength and a rising value of the yield strength after baking can be obtained by controlling hot rolling, cold rolling, continuous annealing temperature and other processes. The invention aims atthe material with processing requirements of axial bearing capacity after can making baking, and the steel plate with axial bearing capacity and excellent formability is obtained according to component and process design. The yield strength of the steel plate is greater than 300 MPa, the strain hardening index (n value) is greater than 0.15, the rising value of the yield strength after baking of the steel plate is no less than 30 MPa, and the axial bearing capacity obtained after the can making baking is no less than 218 kg. The problem that the axial bearing capacity of the steel plate is insufficient after the can making baking is solved.

The invention belongs to the technical field of alloy, and particularly relates to micro-carbon high-strength deep-punching steel with niobium and chromium, and a preparation method thereof. The micro-carbon high-strength deep-punching steel with niobium and chromium comprises the following ingredients, by mass, 0.01% to 0.03% of C, 0.1% to 0.5% of Si, 1.5% to 2.0% of Mn, 0.01% to 0.06% of P, equal to or smaller than 0.015% of S, 0.1% to 0.5% of Cr, 0.01% to 0.05% of Nb, smaller than 0.01% of N, the balance Fe and unavoidable impurities, wherein the molar ratio of Nb to C ranges from 0.05 to 1to 0.3 to 1, and the molar ratio of Cr to C ranges from 1 to 1 to 3 to 1. According to the micro-carbon high-strength deep-punching steel with niobium and chromium, the tensile strength is 510 MPa, the elongation is 29.1%, the strain hardening index is 0.22, the plastic strain ratio is 1.5, and the good strength and the good deep punching performance are achieved as well.

The invention discloses a method for improving stamping forming performance of a graphitized steel plate and belongs to the technical field of steel and iron material processing. The method is characterized in that warm deformation of ferrite dynamic recrystallization is conducted on the graphitized steel plate obtained after graphitization treatment through a warm deformation technology; and thestamping forming performance of the graphitized steel plate is improved by controlling refining and homogenization of ferrite dynamic crystalline grains. The method comprises the specific steps that the graphitized steel plate obtained after graphitization treatment is heated to 550-710 DEG C; after temperature equalization is achieved, flat roll rolling with the rolling reduction being 8-15% is conducted; and after rolling, the graphitized steel plate is air-cooled to the room temperature. According to the graphitized steel plate treated through the method, the ferrite crystalline grains arerefined and homogenized; the stamping forming performance is good; the yield ratio is less than or equal to 0.56; the strain hardening index is greater than or equal to 0.25; and the plane anisotropism is less than or equal to 0.15.

The invention relates to a production method of a light-metal composite plating steel strip for top-grade doors and windows. The production method comprises a cold-rolling procedure and a strip manufacturing procedure, wherein the cold-rolling procedure comprises the following steps of using an ordinary Q215 hot rolled and acid pickled coil as a raw material, performing cold rolling, performing regular degreasing, and performing annealing. The strip manufacturing procedure comprises the following steps of performing uncoiling, performing stripping and removing burrs; and performing physical vapor deposition on metal Al, performing physical vapor deposition on Ti-Mg, performing chemical tinting, performing natural cooling to the room temperature after water scrubbing and stoving are completed, and performing coiling. According to the steel strip produced by the production method disclosed by the invention, the Rel is 480-530MPa; the elongation percentage is 39-43%; the strain hardening exponent n is 0.37-0.47; the plastic strain ratio r is 2.5-3.0; the surface hardness of the plating on the surface of the product is 58-62 HRC; the color of the surface of the plating is bright blue or bright green. After being repeatedly wiped for 10000 times, the changing rate of the hardness valve is less than or equal to 0.1%. According to a comparing test between the light-metal composite plating steel strip disclosed by the invention and a hot-dipped zinc ordinary plate based on routine, when the hot-dipped zinc ordinary plate is exposed for 5400 d under atmospheric environment, the light loss rate is less than or equal to 0.2%, the corrosion area is less than or equal to 0.5%, the surface performance is good and the corrosion resistance performance is good.

The invention relates to a Browman constitutive optimization model of an aluminum ally stress-strain relation and application of the Browman constitutive optimization model. Combined with aluminum alloy stress-strain experimental data, a strength coefficient, a strain hardening index and a strain rate sensitivity index are calculated according to a least square method, a stress-strain relational expression based on the Browman constitutive optimization model is determined, and aluminum alloy performance is predicated. Compared with the prior art, the Browman constitutive optimization model has the advantages of high prediction accuracy and capability of accurately revealing the rule that the stress of aluminum alloy changes along with strain.