Showing papers on "Formability published in 1992"

Effect of Retained Austenite on Formability of High Strength Sheet Steels

Abstract: Effects of retained austenite on press formability were investigated, using austempered 04C-Si-12Mn sheet steels with high tensile strength of more than 980 MPaThe results showed plausible relationships between formability and initial volume fraction of retained austenite (Vγ0) With an increase in Vγ0, height of stretch forming increased linearly to its maximum at about 02Vγ0, and bending as well as expanding of a mechanically ground hole were gradually improved to the best at 015 to 02Vγ0 On the other hand, expanding of a punched hole was slightly deteriorated with increasing Vγ0 in less than 015-02Vγ0 These various types of formability were all extraordinarily deteriorated beyond 02Vγ0 in stretch forming and 015-02Vγ0 in the othersIt was concluded that these effects of retained austenite on formability can be clearly understood in terms of Vγ0 and k: a rate constant relating rate of deformation-induced transformation with uniaxial tensile strain, as a parameter showing stability of retained austenite in press forming

Austenitic high manganese steel having superior formability, strength and weldability, and manufacturing process therefor

Abstract: An austenitic high manganese steel having superior formability, strength and weldability, and a process for manufacturing the steel, are disclosed. The superior formability of the steel is suitable for use on automobiles and electronic panel. The steel has a composition of (in weight %) less than 1.5 % of C, 15.0-35.0 % of Mn, 0.1-6.0 % of Al, and the balance of Fe and other indispensable impurities. The size of the austenite grains is less than 40.0 µm, and, one or more elements are added by selecting them from a group consisting of less than 0.60 % of Si, less than 5.0 % of Cu, less than 1.0 % of Nb, less than 0.5 % of V, less than 0.5 % of Ti, less than 9.0 % of Cr, less than 4.0 % of Ni, and less than 0.2 % of N, thereby providing an austenitic high manganese steel having superior formability, strength and weldability.

Manufacturing process for austenitic high manganese steel having superior formability, strengths and weldability

Abstract: An austenitic high manganese steel having superior formability, strengths and weldability, and a process for manufacturing the steel, are disclosed. The superior formability of the steel is suitable for use on automobiles and electronic panel. The steel has a composition of (in weight %) less than 1.5% of C, 15.0-35.0% of Mn, 0.1-6.0% of Al, and the balance of Fe and other indispensable impurities. The size of the austenite grains is less than 40.0 μm, and, one or more elements are added by selecting them from a group consisting of less than 0.60% of Si, less than 5.0% of Cu, less than 1.0% of Nb, less than 0.5% of V, less than 0.5% of Ti, less than 9.0% of Cr, less than 4.0% of Ni, and less than 0.2% of N, thereby providing an austenitic high manganese steel having superior formability, strengths and weldability.

Forming limit diagrams calculated using Hill’s nonquadratic yield criterion

Abstract: Forming limit diagrams (FLD) are calculated based on an extension of previous analyses by Jones and Gillis[4,5,6] and Choiet al. [8,9] They idealized the sheet metal deformation into three phases: (I) homogeneous deformation up to maximum load, (II) deformation localization under constant load, and (III) local necking with a precipitous drop in load. They described the plastic behavior of sheet metals using a generalized quadratic flow law proposed by Jones and Gillis (JG). In the current analysis, Hill’s nonquadratic flow law for sheets having in-plane isotropy{su[101]} is used in conjunction with the three-stage deformation approximation. Calculated FLDs com- pare very favorably to experimentally determined results for aluminum-killed (AK) steel and aluminum alloys 2036-T4, 1100-H19, 5052-H32, 3003-0, and 3004-0. The comparison is fair for the titanium alloy Ti-6A1-4V. The agreement is poor for the strain rate-insensitive aluminum alloys 5052-0, 5052-H241, 5154-H111, and 6061-T4.

Formability and Corrosion Resistance of TiN-coated Stainless Steel Sheet

Abstract: Refractory binary nitrides such as TiN used as coatings can improve the corrosion resistance of stainless steels. However, the necessary prerequisite is that the coatings are defect-free. Recently it has been proposed that TiN should be deposited directly on stainless steel strip and that moderate plastic forming of the TiN-coated steel may be possible without appreciable cracking. Results from uniaxial and biaxial tensile tests with TiN-coated stainless steels are reported. The surface integrity and possible formation of cracks were studied both visually and by using scanning electron microscopy and scanning tunnelling microscopy. Corrosion tests were carried out to evaluate the performance of the samples after forming. The tests showed that although TiN is a brittle material its adhesion to the substrate is surprisingly good. The coating thickness affected the cracking behaviour. The number of cracks decreased with increasing thickness. The crack pattern changed from transverse to oblique cracking at a particular strain level. The corrosion resistance of the TiN-coated steel was decreased by subsequent forming but it still exceeded that of the stainless steel substrate.

Production of high carbon steel sheet having superior formability

Abstract: PURPOSE:To obtain a high carbon steel sheet having a metallic structure consisting of ferrite, graphite, and cementite and also having superior formability by graphitizing cementite in a high carbon steel having specific composition by subjecting this steel to hot rolling and subsequent annealing alone while obviating the necessity of cold rolling. CONSTITUTION:A steel having a composition which consists of, by weight, 0.30-1.10% C, <=0.20% Si, 0.10-0.50% Mn, 0.05-1.00% sol.Al, and the balance iron with inevitable impurities and in which the contents of P, S, and N as impurities are limited to <=0.020%, <=0.020%, and <=0.013%, respectively, is prepared. This steel is hot-rolled at 600-900 deg.C rolling finishing temp., cooled down to 400-650 deg.C at 5-40 deg.C/sec cooling rate, coiled, and subjected to soaking treatment at a temp. between 600 deg.C and the Ac1 transformation point, by which a metallic structure consisting of ferrite, graphite, and cementite is formed. If necessary, one or more kinds among 0.001-0.01% Ca and/or <=2.00% Ni and 0.0003-0.0050% B are added to the above composition.

Manufacture of galvannealed high tensile strength cold rolled steel plate excellent in corrosion resistance and formability

Abstract: PURPOSE:To obtain a method for manufacturing a galvannealed steel plate having tensile properties such as high tensile strength, low yield ratio and high elongation as well as excellent in rustproofing force and used as an automotive steel plate or the like. CONSTITUTION:Steel constituted of 0.05 to 0.3% C, = Ar3 point finishing temp.) and is cold-rolled and thereafter, the cold rolled plate is applied with preplating (such as Fe-B plating). It is introduced into a continuous galvannealing line, is thereafter annealed at the Ac1 to Ac3 point (for 10 to 300sec holding time), is rapidly cooled from the temp. at >=2 deg.C/sec average cooling rate to form a composite structure of an alpha phase and an alpha' phase and is galvanized and then, the plated layer is applied with an alloying treatment at 450 to 600 deg.C.

High-strength, cold-rolled steel sheet excellent in formability, hot-dip zinc coated high-strength cold rolled steel sheet, and method of manufacturing said sheets

Abstract: A method of manufacturing high-strength, cold-rolled steel sheet excellent in formability. When increasing the strength of extra low-carbon steel as a base material including Nb or a combination of Ti and Nb by adding solid-solution strengthening element thereto, quantities of P and Si to be added which have been used in quantities are decreased whereas Mn and Cr are liberally added. Thus, the yield strength is prevented from increasing and the strength can be increased, whereby a high strength cold rolled steel sheet excellent in surface formability and in resistance to denting can be manufactured.

Determination of Sheet Steel Formability Using Wide Band Electromagnetic-Acoustic Transducers

Abstract: An electromagnetic-acoustic transducer (EMAT) system was used in conjunction with a “sampled” CW signal-processing method to generate, receive, and process longitudinal and shear waves in thin steel sheets. Using the system, swept-frequency measurements were made up to 7.5 MHz. To relate the measurements to sheet steel formability, a dimensionless frequency ratio,K, was computed from the resonant frequencies. From theoretical considerations,K should be related to a measure of steel sheet formability, $$\bar r$$ . This parameter is traditionally measured by plastically deforming uniaxial tension specimens. Good correlation was found betweenK and $$\bar r$$ for a set of steel sheet representative of those typically used to produce automobile body parts.

Aluminum alloy sheet material for wheel rim excellent in formability and strength

Abstract: PURPOSE:To obtain the aluminum alloy sheet material by specifying the composition of an Al-Mg-Si alloy and incorporating specific amounts of Fe and Ti. CONSTITUTION:This Al alloy sheet material has a composition consisting of, by weight, 0.9-2.0% Si, 0.3-2.0% Mg, 0.1-1.0% Fe, 0.005-0.3% Ti, and the balance Al and containing, if necessary, either or both of 0.03-1.5% Cu and 0.03-2.5% Zn and/or one or more kinds among <=0.5 Cr, <=1.3% Mn, <=0.2% Zr, <=1.5% Ni, and <=0.3% V. Si has a function of improving strength by forming together an Mg2Si precipitate together with Mg during coating and heating. When Si content is slightly higher than Mg content, fine Si grains are distributed and, as a result, the degree of work hardening is increased and softening by heating is prevented and also the degree of age hardening is increased. However, when Si content exceeds the upper limit, Si grains are coarsened and formability is deteriorated. As to Mg content, when it exceeds the upper limit, Si grains are decreased and the above effects are reduced. Although Fe and Ti are dispersed in the form of fine compound to refine and uniformize a structure and improve formability, the compound is coarsened and formability is deteriorated when the contents of Fe and Ti exceed the upper limits, respectively.

Device for forming metal sheet by using hydraulic pressure with metal die

Abstract: PURPOSE: To enable forming of materials with low formability by supplying liquid which is a pressure medium; performing a hydraulic forming; pushing a male die, which is provided with a means to prevent the leak of the pressure medium, into a lower die after discharging the liquid and performing the die forming. CONSTITUTION: A thin metal plate, being a material for a press work, is fixed at the edge part by means of an upper blank holder 3 and a lower blank holder 4, a hydraulic pressure is actuated from an entrance provided in the holder 3 and the hydraulic forming is performed. The male die 6 is provided with an O-ring 7, and there is no leak of the hydraulic pressure from the die 6. After the liquid is discharged, forming is performed by lowering the male die 6, and finally by holding the material between the male die 6 and the female die 5, the material is formed with the dies. Thus, forming of the materials having a low formability by means of a conventional metal die method is made possible. Also, the shapeability of a formed article, which is a problem with a conventional hydraulic forming, is improved. COPYRIGHT: (C)1993,JPO&Japio

Production of vessel-shaped filter

Abstract: PURPOSE:To improve thermal formability by using a PP filament of specified birefringence to produce a nonwoven fabric sheet having specified ratio of longitudinal to lateral strength and breaking strength by thermocompression bonding, heating and press-forming the sheet CONSTITUTION:A PP filament having 0005-0019 birefringence ( n) is used to produce a nonwoven fabric sheet 11 having 1-2 ratio (MD/TD) of the longitudinal to lateral strength and >=80% breaking elongation both in longitudinal to lateral direction by thermocompression bonding The sheet 11 is heated to 90-165 degC by heaters 14A and 14B and then press-formed into the shape of a vessel by a press-forming device 15 Consequently, the thermal formability is improved

Production of high strength steel sheet excellent in press formbility

Abstract: PURPOSE:To produce a high strength steel sheet excellent in press formability by utilizing the transformation-induced plasticity of residual austenite. CONSTITUTION:A cold rolled sheet of a steel having a composition which contains 0.06-0.22% C, 0.05-1.0% Si, 0.5-2.0% Mn, and 0.25-1.5% Al and also contains, if necessary, 0.03-0.3% Mo and where the relaion among Al, Si, and C satisfies 0.6Si(%) =5 deg.C/s cooling rate, by which the high strength steel sheet containing residual austenite by 3-20% by volume ratio and excellent in press formability can be obtained. By this method, this steel sheet can be easily produced by using continuous annealing equipment and can also be produced even by using hot dipping equipment, and further, the surface corrosion resistance of the high strength steel sheet can be improved.

Lubricant applied metallic plate for pressing

Abstract: PURPOSE:To obtain a metallic plate excellent in pressing property and spot weldability, adhesive property after press work by applying wax continuously or discontinuously in the form arranging geometrical patterns or other formative patterns regularly or irregularly and exposing a metallic plate base intermittently. CONSTITUTION:When a specified amount of wax solid lubricant is applied regularly or irregularly in geometrical patterns such as a point, a circle, a line or other formative patterns, it acts favorably on press formability but it is unsuitable for spot weldability and adhesive property in the case of uniformly applying the wax solid lubricant on the whole surface of the metallic plate. Excessive reduction of an amount of coating in order to obtain the weldability and adhesive property lowers the press formability and generates a crack and a wrinkle on a product on the contrary, therefore, a normal product can not be obtained. Consequently, for the purpose of satisfying press formability, degreasing property, weldability and adhesive property at the same time, the wax solid lubricant is applied continuously or discontinuously to expose the metallic plate base partially.

Production of hard aluminum alloy sheet for forming

Abstract: PURPOSE:To produce an Al alloy sheet for forming reduced in the occurrence of earing at the time of drawing and excellent in deep drawability while improving strength and formability by subjecting an ingot of Al alloy with a specific composition to hot rolling, process annealing, and cold rolling under respectively specified conditions. CONSTITUTION:An ingot of an Al alloy in which 0.5-5.0%, by weight, Mg and 0.1-1.0% Cu are incorporated as elements for improving strength and also 0.3-1.8% Mn, 0.1-1.0% Si, and 0.2-1.0% Fe are incorporated as elements for improving directional properties and formability to Al is subjected to homogenizing treatment which doubles as heating for hot rolling. Subsequently, the resulting hot rolled plate is process-annealed without delay or is subjected to primary cold rolling and then to process annealing. As to a draft per pass in respective rolling passes at the time of the above process annealing, the draft per pass in the rolling pass in the stage where thickness reduction rate based on the ingot is >=70% is regulated to 5-25%. Subsequent process annealing is performed so that recrystallization ratio becomes >=100%, and cold rolling is exerted, after the above process annealing, at >=40% draft to the final sheet thickness, by which the hard Al alloy sheet for working excellent in strength, directional properties, and formability can be produced.

The use of digital processing in studying stretch-forming sheet metal

Abstract: The objective of this study was to demonstrate the feasibility of upgrading old and tedious approaches of obtaining materials parameters to a computerized process in an affordable, fast and technically efficient manner. The formability and instability of plastic flow in cold-rolled 70/30 cartridge brass in the form of localized deformation is examined using a digital-image-processing technique, allowing for a detailed description of the evolution of the nonuniform deformation pattern in the post-localization regime and making it possible to characterize the localized macroscopic shear bands. Computer interfacing was carried out and a powerful and an efficient package of software was developed for monitoring and managing the DIP system and for analyzing material flow during a uniaxial tension stretching.

Atlas of Formability: Ti-6Al-4V ELI

Abstract: : In this investigation, flow behavior of Ti-6Al-4V ELI alloy was studied by conducting compression tests over a wide range of temperatures and strain rates. Constitutive relations were determined from the flow behavior, and a dynamic material modeling was conducted on this alloy. Thus, the optimum processing condition in terms of temperature and strain rate was identified. Microstructural changes during high temperature deformation were also characterized.... Ti-6Al-4V ELI, Deformation Processing, High temperature deformation, Processing map, Metalworking.

Aluminum alloy sheet excellent in formability and its production

Abstract: PURPOSE:To perform thinning and to provide high strength and high formability by subjecting an ingot of an Al alloy containing Mn, Mg, and specific amounts of Fe and Si to homogenizing heat treatment and also specifying respective conditions in hot rolling, cooling, continuous annealing, and cold rolling. CONSTITUTION:An Al alloy having a composition which consists of, by weight, 0.5-1.2% Mn, 0.5-1.2% Mg, 0.4-0.7% Fe, 0.2-0.5% Si, further 0.05-0.5% Cu and/or 0.05-1.0% Zn, and the balance Al with inevitable impurities and in which the total content of Fe and Si and the ratio of Fe to Si are regulated to 0.7-1.0% and 1.25-2.0, respectively, is cast. The resulting Al, alloy ingot is subjected to homogenizing heat treatment at 500-600 deg.C for >=1hr and then to hot rolling under the conditions of 1.5-2.5mm finishing thickness and 300-360 deg.C finishing temp. Directly after the above or after air cooling, the resulting plate is subjected to continuous annealing where respective rates of heating and cooling are regulated to >=100 deg.C/min and the plate temp. is held at 400-600 deg.C and lowered to =80% rolling rate. By using this Al alloy sheet, cans, etc., can be made lightweight.

Gasket material for internal combustion engine excellent in settling resistance

Abstract: PURPOSE:To obtain a gasket material for internal combustion engine having a dual-phase structure of austenite and strain induced martensite and excellent in settling resistance, strength, formability, and corrosion resistance by regulating the components in an Ni-Cr-Cu alloy steel having a specific composition. CONSTITUTION:As a gasket material for internal combustion engine particularly excellent in settling resistance, a steel material prepared by applying temper rolling to an alloy steel having a composition which contains, by weight, 1.0-3.0% Si, =5% elongation, and the gasket material having >=175kg/mm tensile strength can be obtained by means of ageing treatment after forming into the prescribed shape.

Rolled al-mg alloy sheet for forming at cryogenic temperature

Abstract: PURPOSE:To obtain a rolled Al-Mg alloy sheet having superior formability at cryogenic temp. by regulating the components in an Al-Mg alloy, respective contents of the components, and the crystallinity of structure, respectively. CONSTITUTION:An ingot of an Al-Mg alloy which has a composition containing, by weight, 2.5-8.5% Mg, or further either or both of <1.2% Cu as an element for improving the strength and ductility of alloy and <2.0% Zn as an element for improving strength and stress corrosion cracking resistance, and at least one kind among <0.2% Cr, <0.2% Zr, and <0.2% Mn as crystalline grain refining elements is subjected to soaking treatment, formed into a sheet by means of cold rolling and hot rolling, and then subjected to short-time solution treatment, by which the crystallinity of structure is refined to 10-50mum. By this method, the Al-Mg alloy sheet excellent in formability in a cryogenic atmosphere of liquid nitrogen, etc., can be obtained.

Structural optimization with manufacturing considerations

Abstract: Product design has traditionally been done in a sequential fashion. This often requires extensive iteration between product and manufacturing engineers to insure manufacturability long after the initial product design. Simultaneous engineering attempts to reduce design time by considering both the product and process from the earliest design stage. Toward this goal, we have extended a structural optimization program by incorporating manufacturability requirements for thin-wall beam type members formed by stamping. This was implemented using a new two-piece beam design element which accounts for thinning of the sidewalls during combined stretch and draw forming. Multiple material types and stamping processes are considered. Simple formulae for forming strain and elastic springback after stamping allow us to evaluate the formability of each beam member. The new capability was tested using both simple beam structures and a complete automotive frame structure. Minimum mass designs were then produced while considering both structural and formability requirements. In general, the mass of the optimal designs was near the mass of the same structures designed without manufacturing considerations. This was possible because of the additional design freedom offered by including the sidewall thinning effects.