Showing papers on "Formability published in 1993"

Silicides for integrated circuits: TiSi2 CoSi2

Abstract: Silicides have been a topic of intensive research for more than a decade. The driving force for these investigations has certainly been the interesting materials aspects of the silicides and their applications in integrated circuits. The advantages of easy formability and low resistivity for both CoSi2 and TiSi2 have led to an intensive use of these silicides in self-aligned processes for simultaneous silicidation of source, drain and gate. The fundamental investigations of these silicides include thermodynamic and kinetic aspects of phase formation, interactions with doped Si and related defect generation, and the interaction with oxide and metals. Specific issues related to the technological implementation of silicides in a full process will be discussed in view of the trend to scale the silicided area both in the vertical and in the lateral dimensions.

Unique metallic glass formability and ultra-high tensile strength in AlNiFeGd alloys

Abstract: The metallic glass formability of aluminum-rich AlNiFeGd alloys has been systematically investigated. The critical cooling rate required to form an amorphous state in this system is generally low, and comparable to that of some of the best metallic glass formers, such as PdCuSi. Amorphous ribbons up to 0.25 mm thick can easily be produced by the single-roller melt-spinning technique. Tensile strengths as high as 1280 MPa and Young's modulus of 75 GPa have been obtained. Bulk amorphous alloys with good mechanical properties are optimized in Al 85 Ni 6 Fe 3 Gd 6 . DSC and DTA studies reveal that the glass formability is unique for Al-based alloys because the reduced glass temperature T rg for AlNiFeGd can be as low as 0.44. This is much lower than conventional theory would suggest for easy glass forming systems. A mechanism for the unusual glass formability is suggested.

Advances in aluminium alloy products for structural applications in transportation

Abstract: This paper describes the needs of the aviation and automotive markets for structural materials and presents examples of developments of aluminum alloy products to fill these needs. Designers of aircraft desire materials which will allow them to design lightweight, cost-effective structures which have the performance characteristics of durability and damage tolerance. Their needs are being met by new and emerging materials varying from Al-Li alloys for thick structure, high-strength plate and extrusions for wings, and new monolithic and aluminum-fiber laminates for fuselages. Increase in fuel economy because of lighter weight structure is the driving force for aluminum alloys in the automotive market, and cost is extremely important. Mechanical properties for automotive use also depend on the application, and corrosion resistance must be adequate. For «hang-on» components such as fenders and hoods, formability is typically the limiting mechanical property. Strength must be adequate to resist denting at a thickness which offers cost-effective weight savings over steel. Because formability often decreases with increasing yield strength, alloys which are highly formable in the T4 temper and which age harden during the paint bake operation were developed. Alloys such as 6009 and 6010 are now being challenged by 2008, 6111 and 6016. Body structure components must be made from materials which absorb energy and fail gracefully during a crash. Such components for an automotive space frame are being die cast from an Al-Si-Mg alloy. These ductile die castings are joined to thin 6XXX extrusions which must combine formability, strength, ductility and the ability to deform plastically on impact. Bumpers must combine strength and adequate formability; in the event that current alloys are inadequate for future needs, a new 7XXX alloy offers an improved combination of properties

A better sheet formability test

Abstract: A new test for sheet metal formability was designed, constructed, and used to evaluate several coated and uncoated sheet materials. Results from the OSU Formability Test were also compared with standard limiting dome height (LDH) tests and with finite element simulations. These results show that the new test is more reproducible, even using relatively uncontrolled equipment, more closely follows the desirable plane-strain path, and takes roughly one fifth of the time to perform relative to LDH. Moreover, there is good correlation between formability evaluated using the two tests. Strain measurements and finite element simulations revealed that the improvements are a result of the new test geometry, which produces more stable and repeatable plane-strain states near the fracture location.

Apparatus for evaluating plane strain stretch formability, and method therefor

Abstract: The invention provides an apparatus and a method for evaluating the plane strain stretch formability for thin steel sheets used in automative bodies, so that manufacturing factories and stamping shops can easily evaluate the plane strain stretch formability. The apparatus includes: a lower die (10) and an upper die (9) with a lock bead (8) installed thereon. A test specimen is inserted into between the upper and lower dies (9) and (10), and is clamped by means of the lock bead (8) along the circumferential edge of said test specimen, so that the material of the test specimen should be mobilized into the upper die (9). Then a punch is elevated to apply a stretch forming force on the test specimen, and then, the plane strain stretch formability is evaluated based on the fracture limit punch height at the instant of the fracture. The punch has a saddle-like semi-cylindrical shape.

Cold rolled steel sheet and hot dip zinc-coated cold rolled steel sheet having excellent bake hardenability, non-aging properties and formability, and process for producing same

Abstract: The present invention provides a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet excellent in paint bake hardenability, non-aging properties and formability, and a process for producing the same. In the present invention, an extremely low carbon steel or extremely low carbon steel containing at least one element selected from the group consisting of Ti and Nb is used as a base steel, and Mn and Cr are positively added thereto, whereby the resultant steel has a mixed structure after annealing. Accordingly, there can be obtained a steel sheet having both a high paint bake hardenability and non-aging properties, and being excellent in formability such as an average r-value (deep drawability). With regard to the paint bake hardenability, the present invention may provide a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet to which paint bake hardening may be optionally imparted in an amount as large as about 10 kgf/mm2 and which also have non-aging properties.

Properties of austenitic Fe-25Mn-1Al-0.3C alloy for automotive structural applications

Abstract: Austenitic Fe-25Mn-1Al-03C steel, cold-rolled and annealed at about 800 °C, exhibited 25 times higher tensile strength than current automotive ferritic sheet steel, while possessing comparable formability The formation of strain-induced deformation twinning gave rise to an optimum combination of high strength and good formability

Production of magnesium alloy sheet excellent in press formability

Abstract: PURPOSE: To obtain a magnesium alloy sheet having superior press formability by melting and casting a magnesium alloy containing specific percentages of rare earth metal, zirconium, and zinc and subjecting the resulting ingot to hot rolling and to warm rolling under specific conditions. CONSTITUTION: An alloy, having a composition consisting of, by weight, 0.5-1.5% rare earth metal, 0.1-0.6% zirconium, 2.0-4.0% zinc, and the balance essentially magnesium, is melted and cast. The resulting ingot is hot-rolled and then warm- rolled at 180-230°C, preferably 180-200°C, at a total draft of 40-70%, preferably 40-60%. By this method, the magnesium alloy sheet excellent in press formability can be obtained without deteriorating the characteristics of magnesium alloy. COPYRIGHT: (C)1994,JPO

Production of aluminum alloy sheet excellent in formability and baking hardenability

Abstract: PURPOSE:To produce a sheet, as an Al alloy sheet for forming used for automobile body sheet, etc., excellent in formability and baking hardenability and minimal in secular change at room temp. CONSTITUTION:An ingot of an Al alloy, which has a composition containing 0.3-1.5% Mg and 0.5-2.5% Si as essential components and containing, if necessary, small amounts of Cu, Zn, Mn, Cr, Zr, V, Fe, and Ti, is subjected to homogenizing treatment, hot rolling, and cold rolling. The resulting sheet is subjected to solution heat treatment at >=480 deg.C, cooled down to 50-150 deg.C at >=80 deg.C/min cooling rate, and held at the above temp. for 0.5-50hr (where the relation between temp. T( deg.C) and time (t) (hr) satisfies 100 =80 deg.C/min temp. rise rate at >180-280 deg.C for <=170sec to undergo final heat treatment.

Measurement of texture and formability parameters with a fully automated, ultrasonic instrument

Abstract: A fully automatic, ultrasonic instrument to measure texture and formability parameters on metal sheet is described. Arrays of EMAT transducers are used to transmit and receiveS o Lamb waves propagating at 0°, 45°, and 90° with respect to the rolling direction. By analyzing the frequency dependence of the phase of the received signals, the long wavelength limit of the velocities is obtained. Included is a discussion of this algorithm, and subsequent processing steps to predict the ODC'sW400,W420, andW440. On steel, the prediction of drawability parametersr and Δr based on a correlation developed previously by Mould and Johnson is also discussed. Results of blind field trials at facilities of three suppliers/users of steel sheet for automotive applications and one supplier of aluminum sheet for beverage can production are reported. The former confirmed the Mould-Johnson correlation for lowr material but indicated that refinements are needed for modern steels with highr. The aluminum data suggest a correlation between W440 and the degree of four-fold earing.

The deformation behaviour of alloys comprising two ductile phases—II. Applications of the theory

Abstract: True stress-true strain curves, the mean internal stresses and the in situ stress and plastic strain distribution have been calculated for α-β titanium alloys, ferrite-martensite dual-phase steels and α-γ stainless steels, using the theory developed in Part I. It is shown that the theoretical predictions are in very good agreement with the experimental results drawn from the literature. The effects of microstructural parameters and the effect of differences in the mechanical properties of the constituent phases on the deformation behaviour of these two-ductile-phase alloys are discussed in detail. In contrast to existing deformation theories, the present approach predicts that there are four deformation stages in the total deformation process of two-ductile-phase alloys, and that there should always be a drop in the flow stress after the onset of the plastic deformation in microstructural element III. This phenomenon has been explained in terms of internal stress changes and the balance of the elastic strain energy associated with prior plastic deformation in the three microstructural elements used to describe the overall deformation process.

Manufacture of aluminum alloy sheet excellent in formability

Abstract: PURPOSE:To provide an aluminum alloy sheet for forming excellent in surface quality such as pickups and grain streaks, free from the generation of ribbing marks and the roughening of the surface in drawing and furthermore low in earing ratio as well as small in the dispersion of the above properties in a coil. CONSTITUTION:At the time of manufacturing an Al alloy sheet for forming from an Al alloy ingot contg., by weight, =7 passes, the draft of the final pass in the hot rough rolling is regulated to 30 to 70%, the finishing temp. of the hot rough rolling is regulated to 330 to 370 deg.C as well as the finishing temp. of the hot finish rolling is regulated to 280 deg.C, furthermore, without executing process annealing, the cold draft to the sheet thickness of the final product is regulated to 25 to 70% and annealing is executed at the final sheet thickness.

The development of a mathematical model for predicting the depth of plastic deformation in a machined surface

Abstract: The development and verification of a mathematical model for the prediction of plastic deformation in a machined surface are presented. The main assumption for developing this model is that there is a linear relation between plastic strain and the depth to which it extends. The model relates the work required to shear the workpiece material to the work needed to compress the workpiece material ahead of the cutting tool. The resulting depth of plastic deformation in the machined surface is a function of the true stress-strain characteristics of the workpiece material, the shear stress and shear strain on the shear plane, and the distribution of plastic strain. Results of the model agree well with data found in the literature. An improvement of the model is suggested through application of actual distribution data of plastic strain and calculation of frictional behavior on the rake face of the tool.

Aluminum alloy sheet excellent in press formability and baking hardenability and its production

Abstract: PURPOSE: To provide an aluminum alloy sheet in which at least either press formability and low temp. baking hardenability is moerover improved. CONSTITUTION: An Al alloy essentially consisting of 0.15 to 2.0% Mg, 0.2 to 2.0% Si and 0.03 to 0.3% Sn is rolled, is thereafter subjected to solution treatment and is subjected to preliminary aging at 40 to 130°C×0.5 to 48hr. For obtaining low proof stress and high elongation at the time of forming, the one having a compsn. of 0.15 to 2.0% Mg, 0.3 to 1.5% Si and 0.03 to 0.2% Sn is subjected to preliminary aging at 40 to 100°C×≥2hr. For obtaining excellent low temp. (about ≤170°C) baking hardenability, the one having a compsn. of 0.3 to 1.5% Mg, 0.2 to 2.0% Si and 0.06 to 0.3% Sn is subjected to preliminary aging of holding to 60 to 130°C solution hardening temp. for 0.5 to 48hr. The effect of reducing room temp. age hardening can also be given. Mn, Cr, Zr, Cu, Ag or the like can be added thereto. This alloy sheet is suitable for an automotive body. COPYRIGHT: (C)1994,JPO

Al-Mg ALLOY SHEET EXCELLENT IN PRESS FORMABILITY

Abstract: PROBLEM TO BE SOLVED: To obtain an alloy sheet excellent in bulging formability, deep drawability and a forming crack limit in the place from a tensile region to a plane strain region, as to a texture dominating plastic anisotropy, by controlling the ratio of respective crystal orientations and controlling the crystal grain sizes to specified ranges. SOLUTION: An alloy sheet excellent in bulging formability has a texture in which the volume fractional rate in the CUBE orientation is 5 to 20%, the volume fractional rate in the GOSS orientation is 1 to 5%, and each volume fractional rate in the BRASS orientation, S orientation and COPPER orientation is 1 to 10%, and whose crystal grain size is 20 to 70 μm. An alloy sheet excellent in deep drawability has a texture in which the ratio of the volume fractional rate in the CUBE orientation and the volume fractional rate in the S orientation (S/Cube) is >=1, and that in the GOSS orientation is <=10%, and whose crystal grain size is 20 to 100 μm. As to an alloy sheet high in a forming crack limit in the place from a tensile region to a plane strain region, the volume fractional rate in the CUBE orientation is 30 to 50%, the volume fractional rate in the BRASS orientation is 10 to 20%, and the crystal grain size is 50 to 100 μm.

Method of producing an aluminum alloy sheet excelling in formability

Abstract: A method including preparing an aluminum scrap containing a total of about 0.3 to 2.0 wt % of Fe and Si; melting and then adjusting the material composition so as to attain an Mg content of about 3 to 10 wt % or a composition further containing at least one of the elements Cu, Mn, Cr, Zr and Ti, each in the amount of 0.02 to 0.5 wt %; subjecting the material to casting, hot rolling, cold rolling and continuous annealing to obtain an aluminum alloy sheet having a tensile strength of about 31 kgf/mm2 or more; and applying a lubricant surface coating to impart a coefficient of friction of not more than about 0.11.

High strength aluminum alloy clad excellent in formability

Abstract: PURPOSE: To obtain a high strength Al alloy clad sheet excellent in formability by cladding an Al-Mg alloy having a high concn. of Mg with an Al-Mg alloy having a low concn. of Mg. CONSTITUTION: One side or both sides of an Al-Mg alloy contg. 3.5-10% Mg as a core material are clad with an Al-Mg alloy contg. 0.8-2.0% Mg as a cladding material so that the thickness of the cladding material per one side is regulated to 3-20% of the total thickness and the objective high strength Al alloy clad sheet excellent in formability is obtd. A small amt. of a specified element such as Cu, Zn, Mn, Cr, Zr, V, Fe, Si or Ti may be incorporated into the core material and the cladding material. COPYRIGHT: (C)1994,JPO&Japio

High rigidity steel sheet for vessel and its production

Abstract: PURPOSE: To produce a steel sheet for a vessel excellent in rigidity and flange formability by subjecting dead soft steel having a specified compsn. to hot rolling, cold rolling, annealing and secondary cold rolling at a specified rolling ratio. CONSTITUTION: A slab having a compsn. contg., by weight, 50% draft into a thin steel sheet having ≤0.20mm final sheet thickness. The thin steel sheet for a vessel in which the average ratio of the major axis of the crystalline grains in the structure to the minor axis is regulated to ≥4 and having ≥230000NPa maximum elastic modulus can be obtd. COPYRIGHT: (C)1994,JPO&Japio

High tensile steel sheet having excellent stretch flanging formability

Abstract: A high tensile steel sheet excelling in workability and stretch flanging formability, which is of a composite texture composed of a ferrite phase and a 2nd phase selected from the group consisting of martensite, bainite, pearlite, retained austenite and cold-transformed ferrite, wherein the volume fraction of the 2nd phase is not less than about 1.3 times higher at an outer region of the steel sheet than the volume fraction of the 2nd phase in a central region of the sheet thickness.

High-formability steel plate with a great potential for strength enhancement by high-density energy treatment

Abstract: Disclosed are alloying elements and microstructures suited for realizing a marked increase in strength of low-carbon or ultra-low-carbon steel plate using a high-density energy source such as a laser. Steel blanks satisfying both high formability and high strength requirements are provided which show sufficient press formability and yet can be markedly increased in strength by laser treatment or which have been markedly increased in strength by laser treatment in areas not to be subjected to severe forming.

Aluminum alloy sheet excellent in baking hardenability of coating material and press formability and its production

Abstract: PURPOSE:To provide an aluminum alloy sheet excellent in press formability and excellent in hardenability by low temp. baking and suitable for an automobile body sheet and its manufacturing method. CONSTITUTION:This is an aluminum alloy sheet contg., by weight, 0.4 to 1.5% Mg, 0.24 to 1.6% Si, 0.12 to 1.5% Cu, =0.6Mg (%) and the balance Al with inevitable impurities, in which the average aspect ratio H/L of the crystalline grains is regulated to >=0.7 and having >=20mum average grain size and is a manufacturing method for the above alloy sheet in which an aluminum ally ingot having the above compsn. is subjected to homogenizing treatment at 450 to 580 deg.C, is thereafter subjected to hot rolling and cold rolling into a desired sheet thickness, is heated to the range of 480 to 580 deg.C at >=3 deg.C/sec heating rate, is held for =2 deg.C/sec cooling rate.

Process of hot forging at ultrahigh temperature

Abstract: A process of hot forging a steel at an ultrahigh temperature, comprising the steps of: heating a steel containing less than 1 wt % carbon in an atmosphere substantially composed of a non-oxidizing gas at a high heating rate sufficient for suppressing the oxidation of the steel caused by a residual oxidizing impurity gas in the atmosphere to a temperature either within or slightly below a range in which the steel has a solid-liquid dual phase structure; and forging the heated steel in a hot forging die at a high working speed in accordance with a preheating temperature of the die so that the steel is maintained at a temperature necessary for imparting the steel with a formability necessary for effecting the forging until a desired form is attained.

High strength aluminum alloy clad plate excellent in formability

Abstract: PURPOSE:To obtain a high strength aluminum allay clad plate excellent in formability by cladding an Al-Mn series allay having a low Mn concn. with an Al-Mg series alloy having a high Mg concn. CONSTITUTION:Al-Mg contg. 3.5 to 10% Mg is used as a core material, an Al-Mn series alloy contg. 0.8 to 1.6% Mn is used as a surface material and one side or both sides of the core material are clad with the surface material in such a manner that the thickness of the surface material is regulated to 3 to 20% to the total plate thickness per side. In this way, the high strength aluminum alloy clad plate excellent in formability can be obtd. Moreover, the core material may be incorporated with small amounts of specified elements such as Cu, Zn, Mn, Cr, Zr, V, Fe, Si and Ti, and the surface material may be incorporated with small amounts of specified elements such as Cu, Zn, Zr, Cr, Fe, V, Ti and Si.

Laser Welding Technology for Joining Different Sheet Metals for One Piece Stamping

Abstract: The welding conditions for stamping have been evaluated with successful results in formability and strength. The laser welded blanks made by using this new technology have been applied to actual body components with satisfactory results in material cost savings, improved body accuracy, and decreased body weight..

Deformation texture of hydrostatically extruded polycrystalline NiAl

Abstract: NiAl is currently a candidate for high temperature structural applications because of its high melting temperature, low density, and excellent oxidation resistance. Polycrystalline NiAl possesses low ductility at ambient temperatures, but it has a brittle-to-ductile transition temperature (BDTT) of approximately 573 K (1,2). Its high melting temperature, however, puts limits on its formability, usually requiring it to be processed at high temperatures. High temperature processing can lead to diffusive effects which may nullify the benefits of deformation processing. Processing of NiAl at lower temperatures, yet above its BDTT, might yield the conditions necessary for large amounts of strain to be attained from processing but might also limit the amount of diffusion related phenomena that would occur either during or following high temperature deformation. Deformation textures give insight into the modes of deformation that result from processing. When extruded below approximately 1,173 K, NiAl typically develops a (110) fiber texture. When extruded at higher temperatures or subsequently annealed, a (111) recrystallization temperature develops. The first successful low temperature hydrostatic extrusion of NiAl has been reported recently. It is the purpose of this paper to give the details of the resulting deformation texture and relate it to the potential benefits of processingmore » of NiAl with the use of hydrostatic pressure.« less