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Viewing 1 to 30 of 1553
2011-04-12
Technical Paper
2011-01-0426
Mark E. DeBruin, S. E. Jordan
Significant research has been conducted with the goal of obtaining thin walled ductile iron for use in lighter weight designs. A review is made of the past efforts to achieve thin walled ductile iron. Most past efforts resorted to costly processes or non-standard production practices. Lost Foam Casting (LFC) is an alternate foundry process which used in conjunction with standard melt shop practices results in a massive carbide free structure when used with thin section size. Chemistry, hardness tests, microstructures, and design improvements of a case study are reviewed.
2011-04-12
Journal Article
2011-01-0193
Qigui Wang, Peggy Jones
Cast aluminum alloys are increasingly used in cyclically loaded automotive structural applications for light weight and fuel economy. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the absence of casting flaws, however, crack initiation occurs at the fatigue-sensitive microstructural constituents. Cracking and debonding of large silicon (Si) and Fe-rich intermetallic particles and crystallographic shearing from persistent slip bands in the aluminum matrix play an important role in crack initiation. This paper presents fatigue life models for aluminum castings free of casting flaws, which complement the fatigue life models for aluminum castings containing casting flaws published in [1].
2011-04-12
Journal Article
2011-01-0535
L. Rafael Sanchez PhD, Susan Hartfield-Wunsch
During sheet metal forming, the friction and surface roughness change as the sheet slides, bends and stretches against the tools. This study assessed evolution of friction and surface roughness changes on aluminum sheet with two surface finish conditions, mill finish (MF) and electron discharge texture (EDT), in both the longitudinal and the transverse rolling directions of the sheet. The sheets were tested using a three pin Draw Bead Simulator (DBS). Surface roughness of the sheet evolved as a result of bending at the first shoulder, reverse bending at the middle pin, bending at the second shoulder and unbending at the exit. Stretching conditions and sheet-pin contact were also varied to see the impact on surface roughness. In general, the largest surface roughness change for the transverse direction was observed at the convex side of the exit shoulder pin and on the convex side of the first shoulder for the longitudinal direction.
2011-04-12
Journal Article
2011-01-0534
Susan E. Hartfield-Wunsch, Donald Cohen, L. Rafael sanchez PhD, Lars-Erik Brattstrom
Aluminum sheet is commercially available in three surface finishes, mill finish (MF), electric discharge texture (EDT), and dull finish (DF). This surface finish impacts the friction behavior during sheet metal forming. A study was done to compare ten commercially available sheet samples from several suppliers. The friction behavior was characterized in the longitudinal and transverse directions using a Draw Bead Simulator (DBS) test, resulting in a coefficient of friction (COF) value for each material. Characterization of the friction behavior in each direction provides useful data for formability analysis. To quantitatively characterize the surface finish, three-dimensional MicroTexture measurements were done with a WYKO NT8000 instrument. In general, the MF samples have the smoothest surface, with Sa values of 0.20-0.30 μm and the lowest COF values. The EDT samples have the roughest surface, with Sa values of 0.60-1.00 μm, and the highest COF values.
2011-04-12
Journal Article
2011-01-0533
Susan E. Hartfield-Wunsch, Jamie Burdeski, Elgin Miller, Wei Ji
It is important to understand the accuracy level of the formability analysis for any new process so that correct predictions can be made in product and die design. This report focuses on the formability analysis methodology developed for the preform anneal process. In this process, the aluminum panel is partially formed, annealed to eliminate the cold work from the first step, and then formed to the final shape using the same die. This process has the ability to form more complex parts than conventional aluminum stamping, and has been demonstrated on a complex one-piece door inner and a complex one-piece liftgate inner with AA5182-O3. Both panels only required slight design modifications to the original steel product geometry. This report focuses on the formability analysis correlation with physical panels for the liftgate inner, considering both full panel anneal in a convection oven and local annealing of critical areas.
2011-04-12
Journal Article
2011-01-0488
Sean Mckelvey, Ali Fatemi
Fatigue fractures are the most common type of mechanical failures of components and structures. It is widely recognized that surface finish has a significant effect on fatigue behavior. Forgings can be accompanied by significant surface roughness and decarburization. The correction factors used in many mechanical design textbooks to correct for the as-forged surface condition are typically based on data published in the 1940's. It has been found by several investigators that the existing data for as-forged surface condition is too conservative. Such conservative values often result in over-engineered designs of many forged parts, leading not only to increased cost, but also inefficiencies associated with increased weight, such as increased fuel consumption in the automotive industry. In addition, this can reduce forging competitiveness as a manufacturing process in terms of cost and performance prediction in the early design stage, compared to alternative manufacturing processes.
2013-04-08
Journal Article
2013-01-0829
Alastair Long, David Thornhill, Cecil Armstrong, David Watson
Die pre-heating has a beneficial effect on die life, by reducing thermal shock and stress fluctuations on the die surface. The findings from this paper indicate that the die surface stress decreased by 44% when the die is pre-heated to 150°C, and decreases by 57% when the die is pre-heated to 200°C, in comparison to when the die is started "cold" with an initial temperature of 20°C. Changes to the die start-up procedure, by switching off the die internal water cooling for the first four casting cycles, results in the die heating to operating temperature in fewer casting cycles, resulting in fewer castings being scrapped before the die achieves steady state operating temperature. From this, a saving of four castings per start-up can be made, reducing scrap by 4.5%, leading to lower manufacturing costs, reduced energy usage and increased useful die life.
2013-04-08
Journal Article
2013-01-1166
Cliff Butcher, David Anderson, Michael Worswick
Hole expansion of a dual phase steel, DP600, was numerically investigated using a damage-based constitutive law to predict failure. The parameters governing void nucleation and coalescence were identified from an extensive review of the x-ray micro-tomography data available in the literature to ensure physically-sound predictions of damage evolution. A recently proposed technique to experimentally quantify work-hardening and damage in the shear-affected zone is incorporated into the damage model to enable fracture predictions of holes with sheared edges. Finite-element simulations of a hole expansion test with a conical punch were performed for both a punched and milled hole edge condition and the predicted hole expansion ratios are in very good agreement with the experiment values reported by several researchers.
2013-04-08
Technical Paper
2013-01-1172
ZiQiang Sheng, Yuwei Wang, Tony Chang, Robert Miller, Evangelos Liasi
Hot stamping or so-called continuous press hardening is a process to make sheet metal parts with yield-tensile strength up to 1150Mpa-1550Mpa. Due to the high specific ratio of quenched Boron steels, which is higher than those of aluminum alloys and magnesium alloys, the components with low mass can be made from hot stamped Boron steels. In current industrial practice, direct hot stamping process, which forms a part directly from a flat sheet blank, is normally used to make geometries with relatively mild deformation, such as B-pillars, A-pillars etc. In this study, indirect hot stamping is introduced to develop geometries with a deep cavity and complex form features. Since the indirect hot stamping develops the part cavity depth in cold drawing and then forms detail features in hot stamping, part with complex geometry can thus be formed. A rocker component is chosen to demonstrate the technology.
2013-04-08
Journal Article
2013-01-1026
Meng Wang, Henry Hu
Recently, joining of cast aluminum components with wrought and/or cast similar metals becomes an urgent task for the auto industry to develop light-weight complex and large-scale chassis and body structures for further reduction in vehicle weight. In this study, fusion-joining of vacuum high pressure die cast (VHPDC) alloy A356 subjected to T5 heat treatment and wrought alloy 6061 with the Gas Metal Arc Welding (GMAW-MIG) process was experimented in an effort to understand the effect of the MIG process on the microstructure development and tensile behaviors of the base alloys (T5 A356 and 6061), Heat Affected Zone (HAZ) and Fusion Zone (filler metal ER4043). The results of tensile testing indicated that the ultimate tensile strength (UTS), yield strength (YS) and elongation (Ef) of VHPDC T5 A356 were relatively high, compared to both wrought alloy 6061 and the filler metal (ER 4043).
2004-03-08
Technical Paper
2004-01-1581
Mike Guo, Ram Bhandarkar, Barry Lin
Loads generated during assembly may cause significant stress levels in components. Under test conditions, these stresses alter the mean stress which in turn, alters the fatigue life and critical stress area of the components as well. This paper describes the Finite Element Analysis (FEA) procedure to evaluate behavior of a cast aluminum wheel subjected to the rotary fatigue test condition as specified in the SAE test procedure (SAE J328 JUN94). Fatigue life of the wheel is determined using the S-N approach for a constant reversed loading condition. In addition, fatigue life predictions with and without clamp loads are compared. It is concluded that the inclusion of clamp load is necessary for better prediction of the critical stress areas and fatigue life of the wheel.
2004-03-08
Technical Paper
2004-01-1499
S. Shamasundar
Crankshaft is the most critically loaded part in the auto assembly. Crankshafts are increasingly made by steel forging to achieve required mechanical properties. New grades of steels such as air cooled forging steels and micro alloyed steels are used for crankshaft forging. Non-linear FEM analysis based process modeling can be applied to the forging of crankshafts. In the paper, authors discuss the application of FEM analysis based process modeling of crankshaft forging for analysis of grain flow and heat treatment. Three case studies are presented. In the first case, the grain flow evolution during the forging is presented in different cross sections. By an analysis of the velocity vectors, defects such as laps, folds, and underfills in forged crankshafts can be predicted. In the second case, the effect of centerline segregation causing a crack in the crankshaft is discussed.
2004-03-08
Technical Paper
2004-01-1671
Kazuhiro Hatano, Seiji Hibi, Masahiro Nakamura
From the viewpoint of measures for environmental issues, the amount of solvents in paint for aluminum wheels needs to be minimized. Environmentally friendly powder coatings have been used widely for primer coating and clear coating, but there is no precedent for its use for base coating. This time, we optimized the condition of surface treatment of pigment and hardening behavior of constituent resin in the melting process and succeeded in developing a metallic powder coating for aluminum wheels that fulfills the appearance and the quality requirements of aluminum wheels.
2004-03-08
Technical Paper
2004-01-1022
H. Mancha-Molinar, H. F. López, A. Silva, K. Still
Alloy A319 is extensively used in the automotive industry. In the as-cast condition the alloy lacks the required strength. A solid solution heat treatment (T4) followed by room temperature quenching improves tensile strength. Accordingly, engine castings in T4 condition are used in the manufacture of automobiles. However, A319 alloy is not thermodynamically stable after solid solution. The matrix is supersaturated with Cu, and a precipitation sequence is expected to occur overtime, which leads to dimensional changes. Alternatively, an aging treatment (T7) can activate the precipitation reactions to achieve dimensional stability in castings. In this work, dilatometric measurements were made during a T7 heat treatment in order to establish the extent of dimensional changes, resulting from the precipitation reactions. In addition, high-resolution electron microscopy was used to follow up the precipitation reactions.
2004-03-08
Technical Paper
2004-01-1021
Rathindra DasGupta, Sumantra DasGupta, Craig Brown
The basic data on the mechanical properties of a casting are frequently obtained from a tensile test, in which a suitable specimen machined from the casting is subjected to increasing axial load until it fractures. The engineering tension test is widely used by casting manufacturers as an acceptance test for customer specifications. However, tensile bars machined from castings often provide undesirable information, thereby leading one to question the part integrity. This paper, therefore, discusses the various factors that affect tensile properties obtained from specimens machined from actual castings.
2004-03-08
Technical Paper
2004-01-1029
Carlos C. Engler-Pinto, John V. Lasecki, James M. Boileau, John E. Allison
The high temperature fatigue behaviors of three cast aluminum alloys used for cylinder head fabrication - 319, A356 and AS7GU - are compared under isothermal fatigue at room temperature and elevated temperatures. The thermo-mechanical fatigue behavior for both out-of-phase and in-phase loading conditions (100-300°C) has also been investigated. It has been observed that all three of these alloys present a very similar behavior under both isothermal and thermo-mechanical low-cycle fatigue. Under high-cycle fatigue, however, the alloys A356 and AS7GU exhibit superior performance.
2004-03-08
Technical Paper
2004-01-1027
John C. Hebeisen, Bruce M. Cox
Hot Isostatic Pressing (HIP) has been routinely used to densify castings for aerospace and medical applications for over 30 years. While HIP is widely known to improve the toughness and fatigue life of castings through the healing of internal porosity, it has been perceived as too expensive for most cast aluminum alloys for automotive applications. Recent developments suggest that the cost effectiveness of certain special HIP processes should be revisited due to reductions in process cost and improvements in throughput. This paper will evaluate the Densal® II process applied to a front aluminum steering knuckle. Two casting processes representing differing levels of relative cost and quality were evaluated. The first was Alcoa's VRC/PRC process, a metal mold process with bottom fill, evacuation before fill and pressurization after fill. This is considered to be a premium quality, but higher cost casting process that is already qualified for this application.
2004-03-08
Technical Paper
2004-01-1019
Stephen J. Mashl, Matthew M. Diem
The temperature range used for HIP processing of cast aluminum parts is also appropriate for solution heat treatment. Integration of these two processes should decrease processing time, energy consumption, and processing cost. In this study, Al-Si-Mg castings were subjected to a combined HIP and T6 heat treatment. The properties and microstructure of these castings were compared to parts processed using conventional methods. Apparent differences in the oxide concentration provided insight into the effect of oxide inclusions on HIP response. Results indicate that fatigue life is increased using an integrated HIP/heat treat process, however, oxide contamination can negate this improvement.
2004-03-08
Technical Paper
2004-01-0743
Jianghuai Yang, Susil K. Putatunda
An investigation was carried out to examine the influence of austempering temperature on strain hardening behavior of austempered ductile cast iron (ADI). Cylindrical tensile specimens of nodular ductile cast iron were austempered by the conventional single-step austempering process at several temperatures. Strain hardening exponent (n values) of all these specimens were determined over the entire plastic deformation regions of the stress-strain curves. Optical microscopy and X-Ray diffraction analysis were performed to examine mechanisms of strain hardening behavior in ADI under tensile loading. Test results show that strain hardening behavior of ADI is influenced by austempering temperature and microstructural variables.
2004-03-08
Technical Paper
2004-01-0876
Dan Zhang, Sherman Y. T. Lang
This paper presents the conceptual design of 5dof tripod-based parallel kinematic machine system to be applied in the magnesium alloy castings finishing industry. The design starts from the industrial requirements and process needs, then propose the most promising architecture and mobility. With the structure, kinematic/dynamic analysis is conducted, and stiffness model is established, it can be further used for stiffness control and design optimization. The genetic algorithms is applied for structure optimization. Finally, an experiment of prototype is setup to validate the methods and models.
2004-10-26
Technical Paper
2004-01-2677
David Milligan, Ulf Engström, Ryu Goto
Powder Metallurgy (P/M) is an increasingly viable alternative for applications requiring high material performance. Continuous advances in alloy systems and processing techniques, combined with powder metallurgy's ability to produce complex net shapes, have made it possible for powder metallurgy to compete with other technologies in engine and transmission applications. This paper will focus on new alloy systems and advanced processing techniques. The properties achievable with currently available materials, such as chromium containing materials, combined with advanced processing techniques, such as warm compaction and surface densification, will be presented. Additionally, a case study where a warm compacted synchronizing latch cone in a heavy duty truck transmission was found to have equal or superior performance to precision forged and powder forged latch cones.
2004-10-10
Technical Paper
2004-01-2767
Werner Oesterle, Ingrid Urban
The Focused Ion Beam (FIB) technique combined with Transmission Electron Microscopy (TEM) was used here for the first time to reveal the microstructure of thin surface layers on brake pads and rotors after a run-in period during which a stable coefficient of friction had developed. Generally the outermost layers of both, pad and rotor, comprise a complicated structure of nanocrystalline metal and metal oxide particles embedded in an amorphous matrix. Obviously oxidation plays a major role and the third body seems to behave like a granular medium. The contact areas were no protuberant plateaus in the regarded case. Therefore the flow of the granular third body layer seems to control friction force rather than ploughing of asperities.
2004-10-26
Technical Paper
2004-01-2739
Saveliy M. Gugel
This article describes the experience of Sanova-Polytech, Inc. (SPI) in the creation, testing, and usage of new Liquid Induction Thermochemical Processes (LINTERPROCESS™) and Liquid Induction Heat Treatment (LINHEAT™) technologies, and in the designing, manufacturing, and employment of new automatic computerized production equipment, which can be of significant advantage to manufacturers of commercial vehicles. Heat treatment and thermochemical processing of various metals play an important role in the global effort to produce stronger, lighter, and more durable machine parts at lower costs. They are widely used in the manufacturing of cars and buses, and farm, construction, industrial, and other machinery.
2004-11-16
Technical Paper
2004-01-3295
Danilo Maciel Barquete, Evaldo José Corat, Carlos de Moura Neto
CVD diamond film deposition on WC-Co substrate is the most likely application of diamond CVD technology towards large scale production, due to its suitability to aluminium alloys machining in the automotive and aerospace industry. Several film-substrate interfaces and surface modifications have been developed aiming higher levels of simultaneous diamond film-substrate adherence and substrate surface toughness, however the results are still far bellow industry requirements for widen scale application. In this work a new interface is introduced in the CVD diamond films technology, which consists of a thermo-reactive deposited and diffused vanadium carbide layer, highly adequate to diamond films deposition on cemented carbide cutting and forming tools. This interface presents good diamond growth characteristics, thermal expansion coefficient similar to the substrate and, in addition, high hardness and mechanical strength.
2004-11-16
Technical Paper
2004-01-3353
Vinicius André Rodrigues Henriques, Carlos Alberto Alves Cairo, Cosme Roberto Moreira da Silva, Carlos de Moura Neto
The automotive industry has identified several automobile components that could be replaced with titanium alloy components, either through direct replacement in existing designs or, preferably, in new designs to fully exploit the unique properties of titanium. The alloy processing by powder metallurgy (M/P) eases the obtainment of parts with complex geometry and, probably, cheaper. In this work, results of the Ti-35Zr-10Nb alloy production are presented. This alloy due to its high wear, impact and corrosion resistance is a promising candidate for automotive applications. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900-1400 °C, in vacuum. Sintering behavior was studied by means of dilatometry.
2004-11-16
Technical Paper
2004-01-3339
Dalcy Roberto dos Santos, Marcelo dos Santos Pereira, Vinicius André Rodrigues Henriques, Carlos Alberto Alves Cairo
Titanium and its alloys provide high strength-to-weight ratios, good fatigue strength and increased corrosion resistance compared with others materials. Its acceptance in aerospace has been limited by costs considerations such as high cost of raw material, high buy-to-fly ratios and expensive machining operations. Significant cost reductions can be obtained by vacuum sintering and powder metallurgy (P/M) techniques by producing near net shapes and consequently minimizing material waste and machining time. The Ti 35Nb alloy exhibit a low modulus of elasticity. Stemming from the unique combination of high strength, low modulus of elasticity and low density, this alloy is intrinsically more resistant to shock and explosion damages than most other engineering materials. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 and 1600 °C, in vacuum.
2004-11-16
Technical Paper
2004-01-3403
Ricardo Millego de Castro, Gilberto Francisco Martha de Souza
The purpose of this paper is to analyze the durability behavior of helical gears in manual automotive gearboxes. It shows the evolution of a certain mating gear applied in a specific durability vehicle test where the gears were modified in some design parameters, such as material type, shot-peening, increase of gear width and lead corrections (micro-geometry). This paper intends to evaluate some design parameters and gear life factors that define the mating gear durability and compare the theoretical results against to the practical ones. These gear life factors (application factor, contact factor, material type, etc) are enclosed in known standards (i.e. DIN 3990). The study shows the necessity of testing automotive transmissions in the beginning of design development. This is the best way to identify some failure modes that were not foreseen by the first calculations and hypothesis.
2004-11-16
Technical Paper
2004-01-3395
Gislene Valdete Martins, Vinicius Andre Rodrigues, Cosme Roberto Moreira da Silva, Carlos Alberto Alves Cairo
In this work, samples of Ti-Nb alloys were obtained by the blended elemental technique using hydride-dehydride (HDH) powders as raw material, followed by uniaxial and cold isostatic pressing with subsequent densification by sintering. It was observed the influence of the processing parameters and chemical composition of the elementary powders on the final microstructure. The samples showed high densification and homogenous microstructure.
2013-01-09
Technical Paper
2013-26-0075
Prakash S
As we all know the price of Cu alloy keep on increasing trend and in few products like motors, generators and power electronics. Cu price plays a vital role in determining the cost. Particularly in power electronics products for the hybrid electric vehicles the electrical/thermal conductivity property of Cu alloy needs to be enhanced since of high voltage requirement within a small space. Many research activities are ongoing to enhance the properties of Cu metal by addition of various alloys compositions. In addition to that the extra-ordinary properties of Carbon Nanotube (CNT) in Metal Matrix Composite (MMC) were main focus for science and technology. Few successful attempts have been made for Copper-Carbon nanotube (Cu-CNT) composites by powder metallurgy techniques, also it was reported the issues on the detoriation of the CNT's properties due to mechanical working.
2013-10-07
Technical Paper
2013-36-0420
Sérgio Augusto Vicente Paula, Ludmila Corrêa de Alkmin e Silva, José Alexandre
Finishing surface has an enormous influence on many important physical phenomena such as contact mechanics, sealing, adhesion and friction. In this paper we will present a brief review of contact mechanics and the influence of different process in the finishing surface as the roundness and roughness. For each process step for ball bearing will be explain and different surface parameter will be measure, also the results will be analyze the influence of the process in the finishing surface. A DOE experimental methodology will be use to reach more accurate results with fewer trails and faster response. Also will present new results and a few comments related to a fabrication process.
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