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2018-04-09 ...
  • April 9-10, 2018 (8:30 a.m. - 4:30 p.m.) - Detroit, Michigan
  • June 21-22, 2018 (8:30 a.m. - 4:30 p.m.) - Hamburg, Germany
  • October 9-10, 2018 (8:30 a.m. - 4:30 p.m.) - Troy, Michigan
Training / Education Classroom Seminars
Advanced High Strength Steels (AHSS) are now commonly used in automotive body structural applications. The high strength of this grade classification is attractive to help reduce mass in the automotive body through reduction in thickness. Strength also supports improvements in safety requirements so that mass increases are minimized. In some specific grades of AHSS, energy absorption is possible in addition to the high strength. This course will review the definition and properties of AHSS and cover several common applications in automotive body structures.
2010-04-12
Technical Paper
2010-01-0448
Raj Sohmshetty, Rakshit Ramachandra, Alavandi Bhimaraddi
Typical automotive body structures are assemblies of stamped steel parts. The stamping process work hardens and thins the parts. The work hardening effects are more pronounced for advanced high strength steels such as DP600. It is now widely accepted in the industry that forming effects must be incorporated into the product attribute models to improve simulation accuracy. This paper investigates some of the challenges in incorporating the forming effects into product attribute models during the automotive product development process and presents solutions. It also investigates how the significance of the coupled forming to attribute CAE method varies based on the initial design thickness of a part. The paper concludes by reviewing component and vehicle level results achieved by the incorporation of the coupled process.
2010-04-12
Journal Article
2010-01-0438
Yoshitaka Okitsu, Tadashi Naito, Naoki Takaki, Tomoaki Sugiura, Nobuhiro Tsuji
Mechanical properties, formability and crash worthiness of a new sheet steel having an ultrafine grained (UFG) multi-phase (MP) microstructure are shown. The fabricated UFG-MP steel showed significant work hardening caused by deformation induced martensitic transformation of retained austenite, which resulted in a combination of high strength and large tensile elongation. It was confirmed by dynamic collapse test and FEM simulation that the large work hardenability of the UFG-MP steel promoted compact mode collapse that improved the absorbed energy.
2010-04-12
Technical Paper
2010-01-0441
Constantin Chiriac
One of the concerns for advanced high strength steels (AHSS) in stamping operations is the failure of sheared edges in stretching modes. When a forming operation requires stretching edges, local formability becomes a very important factor of the material application, particularly for the AHSS. The local formability of a material is usually characterized by the hole expansion ratio (HER). During edge stretching, the sheared edge can be in contact with the tool or it can be free. These two conditions can be simulated by the hole expansion (HE) test using a conical punch and a flat bottom punch, respectively. In this study, the local formability of a dual phase (DP) 780 steel is evaluated using the HE test. The hole expansion tests were performed using a digital record and measurement system (DRMS) which allows the measurement of the final diameter of the hole at the moment of a localized fracture or a through-thickness crack at the hole edge.
2010-04-12
Technical Paper
2010-01-0434
Jagdeesh Bandekar, Michael R. Golden, Greg Meyers, Benda Yan, Jeffrey L. Fenton
Adhesive bonding technology is rapidly gaining acceptance as an alternative to spot welding. This technology is helping automobile manufacturers reduce vehicle weight by letting them use lighter but stronger advanced high strength steels (AHSS's). This can make cars safer and more fuel efficient at the same time. The other benefits of this technology include its flexibility, ability to join dissimilar materials, distribute stress uniformly, provide sealing characteristics and sound dampening, and provide a moisture barrier, thus minimizing the chance for corrosion. The lap shear work reported in the late 1980s and early 1990s has led to the prevalent perception that the galvannealed (GA) coating can delaminate from the steels, resulting in poor joint performance. However, the above work was carried out on steels used primarily in automobile outer body panels.
2010-04-12
Technical Paper
2010-01-0435
S. Xu, W. R. Tyson, P. Martin, N. Petri
Use of ultra high strength steel (UHSS) sheet in automotive components has potential to simultaneously reduce weight and increase crashworthiness. For crashworthiness design and simulation, constitutive equations are required; however, these are scarce for UHSS. Also, UHSS sheets may suffer unexpected fracture such as shear fracture, and toughness data for UHSS sheets is very limited. In this work, effects of strain rate and temperature on flow stress of two UHSS sheet steels (a dual-phase ferritic/martensitic DP980 and a martensitic boron (B) steel) are experimentally investigated and compared to a simple constitutive equation for structural steels based on thermal-activation theory of dislocation motion. The flow stress of the two UHSS steels obeys a constitutive equation similar to that of structural steels of other microstructures (ferrite, ferrite/pearlite, pearlite, ferrite/bainite, and bainite).
2010-04-12
Technical Paper
2010-01-0446
Ramakrishna Koganti, Adrian Elliott
With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5-10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat-affected zones (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.0 mm Usibor® 1500 steel to uncoated Dual Phase 780 (DP780) steel was investigated. The objective of the study was to understand the wire feed rate (WFR) and torch (or robot) travel speed (TTS) influence on lap joint tensile strength.
2010-04-12
Journal Article
2010-01-0447
Joseph A. Ronevich, John G. Speer, David K. Matlock
The susceptibility of Advanced High Strength Steels (AHSS) to hydrogen embrittlement (HE) was evaluated on selected high strength sheet steels (DP 600, TRIP 780, TRIP 980, TWIP-Al, TWIP, and Martensitic M220) and the results were compared to data on a lower strength (300 MPa tensile strength) low carbon steel. Tensile samples were cathodically charged and then immediately tensile tested to failure to analyze the mechanical properties of the as-charged steel. The effects of hydrogen on deformation and fracture behavior were evaluated through analysis of tensile properties, necking geometry, and SEM images of fracture surfaces and metallographic samples of deformed tensile specimens. The two fully austenitic TWIP steels were resistant to hydrogen effects in the laboratory charged tensile samples.
2010-04-12
Journal Article
2010-01-0444
Vesna Savic, Louis Hector, Keith Snavely, Jason Coryell
Quasi-static tensile properties of TRIP590 steels from three different manufacturers were investigated using digital image correlation (DIC). The focus was on the post-uniform elongation behavior which can be very different for steels of the same grade owing to different manufacturing processes. Miniature tensile specimens, cut at 0°, 45°, and 90° relative to the rolling direction, were strained to failure in an instrumented tensile stage. True stress-true strain curves were computed from digital strain gages superimposed on digital images captured from one gage section surface during tensile deformation. Microstructural phases in undeformed and fracture specimens were identified with optical microscopy using the color tint etching process. Fracture surface analyses conducted with scanning electron microscopy and energy dispersive spectroscopy were used to investigate microvoids and inclusions in all materials.
2010-04-12
Journal Article
2010-01-0424
Venkata S. Chevali, Michael Fuqua, Shanshan Huo, Chad Andrew Ulven
Lignocellulosic agricultural by-products can be utilized for an array of biocomposite material applications. Biocomposite properties can approach those of synthetic conventional composites. They are highly suitable for automotive applications, where the thrust is toward fuel economy, weight-reduction, and higher renewability. A common automotive polymer for biocomposite application is alloyed acrylonitrile butadiene styrene (ABS), whose extensive usage can be attributed to its exceptional balance of properties. However, the low sustainability of ABS in environmental degradation entails the addition of fillers. In this study, the UV blocking properties of lignin component of natural fibers will be analyzed for their use as additives in a natural ABS grade and will be compared to an ABS grade compounded with a traditional UV inhibitor.
2010-04-12
Technical Paper
2010-01-0445
Ramakrishna P. Koganti, Adrian Elliott, Donald F. Maatz
There has been a substantial increase in the use of advanced high strength steel (AHSS) in automotive structures in the last few years. The usage of these materials is projected to grow significantly in the next 5-10 years with the introduction of new safety and fuel economy regulations. AHSS are gaining popularity due to their superior mechanical properties and use in parts for weight savings potential, as compared to mild steels. These new materials pose significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application on future vehicle programs. Due to the high strength nature of AHSS materials, higher weld forces and longer weld times are often needed to weld these advanced strength steels.
2010-04-12
Technical Paper
2010-01-0422
Alireza Javadi, Srikanth Pilla, Shaoqin Gong, Yottha Srithep, Jungjoo Lee, Lih-Sheng Turng
Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/coir fiber composites were prepared via both conventional and microcellular injection-molding processes. The surface of the hydrophilic coir fiber was modified by alkali and silane-treatment to improve its adhesion with PHBV. The morphology, thermal, and mechanical properties were investigated. The addition of coir fiber (treated and untreated) reduced cell size and increased cell density. Further decrease in cell size and increase in cell density was observed for treated fibers compared with PHBV/untreated fiber composites. Mechanical properties such as specific toughness and strain-at-break improved for both solid and microcellular specimens with the addition of coir fibers (both treated and untreated); however, the specific modulus remained essentially the same statistically while the specific strength decreased slightly.
2010-04-12
Technical Paper
2010-01-0426
Shanshan Huo, Michael Fuqua, Venkata S. Chevali, Chad A. Ulven
Natural fibers have shown promise as reinforcement in polymer matrix composites in automotive applications. Due to the presence of hydroxyl groups from cellulose and lignin, natural fibers exhibit highly hydrophilic properties. This makes fiber-matrix adhesion very difficult because most structural polymers are hydrophobic in nature. Therefore, in order maximize natural fiber reinforced composite performance, fiber surface modification is required. In addition, a chemical additive to polymer matrix is another direction to improve the performance. In this study, several types of natural fibers were chosen, including European flax fiber, North American flax, and North American hemp fiber. Sodium hydroxide treatment followed by acrylic resin treatment was investigated for its influence on vinyl ester cure kinetics and interfacial properties.
2010-04-12
Technical Paper
2010-01-0423
Andrea Pilon, Ahmed Touny, Joseph Lawrence, Sarit Bhaduri
In this study, we have developed a nanofibrous scaffold infused with functional particulates of calcium phosphate cement via the electrospinning process to be used for tissue engineering applications. PLA and monetite cement were chosen for the development of these bionanocomposites because of their biocompatibility and biodegradability. The calcium present in the monetite cement has been used to enrich the environment for compatibility with bone cells. The various parameters influencing the electrospinning process were varied in order to find the optimum conditions for producing uniform fibers. Using characterization methods such as SEM, XRD, and STEM the fiber morphology, chemical composition, and dispersion of cement particles in the fibers were determined. Higher ratios of monetite to PLA in the fibers significantly affected the electrospinning process and the morphology of the fibers.
2010-04-12
Journal Article
2010-01-0428
Michael Fuqua, Shanshan Huo, Venkata S. Chevali, Chad A. Ulven
In this study, soy-based polyurethane foam was reinforced with random oriented flax fiber to create green composite paneling. This paneling can be used as replacement for plywood in mass transit flooring. To establish optimal material properties, the flax/foam composite's density was modified through manipulation of both fiber volume fraction and foam void content in order to determine processing modification upon mechanical performance. Both static flexural testing and dynamic low velocity impact was performed. Mechanical characterization was performed by both flexural testing and screw fastener pullout studies. Resultant properties demonstrate the feasibility of lower maintenance renewable composite materials as replacement for current transit flooring.
2010-04-12
Technical Paper
2010-01-0433
Ioan Hociota, Pankaj K. Mallick
Among the various high strength steels available today, boron steels are finding increasing applications in bumper beams and other crash resistant structures, primarily for their high strength. However, to overcome the forming difficulty at room temperature and to achieve the microstructural changes needed for high strength, manufacturing of boron steel parts is done under hot forming conditions. In this study, the effect of three principal bumper design parameters, namely depth, thickness and corner radius on the formability of a hat section bumper beam was considered. Using a forming simulation program, 27 different combinations of these three design parameters were examined for forming limits, failure types and failure locations. The bumper beams were also examined for energy absorption in pendulum impact tests. Recommendations are made for the design of boron steel bumper beams based on both impact energy absorption and formability.
2010-04-12
Technical Paper
2010-01-0429
Anjali Milind Rahatgaonkar
A functionalized, significantly hydrophilic Quinoline-Chitosan (QC) biocomposite was chemically synthesized and characterized by ₁H NMR, ₁₃C NMR and FTIR techniques. FTIR spectra revealed a strong interaction between the 2-chloro-3-formyl-7-iminobenzal guinoline scaffold and Chitosan. ₁H NMR results suggested a degree of substitution (DS) ranging from 0.18 to 0.832. The chelating efficiency and selectivity towards transition metal ions, when investigated at pH ranging from 1-8, showed maximum selectivity and affinity for Cu++ as compared to Cd++, Ni++, Co++ at 1-3 pH. This selectivity appeared to be independent of the size and the hardness of the ions. This order in the selectivity was confirmed with potentiometric and spectrophotometric methods and did not depend on the physical form of quinoline-chitosan (QC) biocomposite. Our results prompted us towards further investigating the use of QC as a green depolluting agent.
2011-04-12
Technical Paper
2011-01-0427
Daniel S. Codd
Martensitic stainless steels are ideally suited for structural components and assemblies, satisfying the requirements of high strength, toughness and corrosion resistance with ease of forming in the annealed state. New developments in welding and thermal processing, coupled with increased demands for high strength lightweight structures, are positioning martensitic stainless as a cost effective alternative to conventional lightweighting materials. Several examples are shown, including the development of fully martensitic (UNS S41000) automotive subframes, door beams, B-pillars, seat rails, tow hooks and fuel rail assemblies. The excellent mechanical properties of hardened martensitic stainless allow for notable weight savings, achieving 35% or greater weight reduction relative to baseline designs.
2011-04-12
Technical Paper
2011-01-0425
Jody Shaw, Yukihisa Kuriyama, Marc Lambriks
FutureSteelVehicle’s (FSV) objective is to develop detailed design concepts for a radically different steel body structure for a compact Battery Electric Vehicle (BEV). It also will identify structure changes to accommodate larger Plug-In Hybrid (PHEV) and Fuel Cell (FCEV) vehicle variants. The paper will demonstrate seven optimised structural sub-systems that contribute to the programme's 35 percent mass reduction goals and meet its safety and life cycle emissions targets. It will explain the advanced design optimisation process used and the resulting aggressive steel concepts.
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
2011-01-0019
Kyoo Sil Choi, Ayoub Soulami, Wenning Liu, Xin Sun, Moe Khaleel
In this paper, the microstructure-based finite element modeling method is used in investigating the loading path dependence of formability of transformation induced plasticity (TRIP) steels. For this purpose, the effects of different loading path on the forming limit diagrams (FLD) of TRIP steels are qualitatively examined using the representative volume element (RVE) of a commercial TRIP800 steel. First, the modeling method was introduced, where a combined isotropic/kinematic hardening rule is adopted for the constituent phases in order to correctly describe the cyclic deformation behaviors of TRIP steels during the forming process with combined loading paths which may include the unloading between the two consecutive loadings. Material parameters for the constituent phases remained the same as those in the authors' previous study [ 1 ] except for some adjustments for the martensite phase due to the introduction of the new combined hardening rule.
2011-04-12
Journal Article
2011-01-0232
Hong Yao, Sriram Sadagopan
To improve the formability of advanced high strength steels, the interaction between steel sheet, tool material and tool coating was investigated. Square cup drawing experiments were conducted to determine the range of binder forces for forming good cups without wrinkling or splitting. Binder Span of Control (BSC) tests were conducted for DP590, TRIP590, DP780, DP780 EG and DP980 using three uncoated tool steels and two coatings on a standard tool steel substrate. The experimental results indicate that the binder span for forming good cups is sensitive to the choice of tool material and tool coating and the effect of lubricant on formability also varies with tooling material and coating. The obtained binder spans were compared and the best coating plus tool steel combinations for steels of different grades were identified. In addition, roughness of the tooling surface was measured before and after stamping.
2011-04-12
Journal Article
2011-01-0234
Gang Huang, Benda Yan, Z. Xia
The r-value is a very important parameter in the forming simulations of high strength steels, especially for steels with prominent anisotropy. R-values for sheet steels conventionally measured by extensometers were found neither consistent nor accurate due to difficulties in measuring the width strain. In this study, the Digital Image Correlation (DIC) technique was applied to determine r-values in Longitudinal (L), Transverse (T) and Diagonal (D) directions for cold rolled DP980 GI, DP780 GI, DP600 GI and BH250 GI sheet steels. The r-values measured from DIC were validated by finite element analysis (FEA) of a uniaxial tensile test for BH250. The simulation results of the load-displacement for two plasticity models were compared to experimental data, with one being the isotropic yield (von-Mises) and the other being an anisotropic model (Hill-48) using the r-value measured from DIC.
2011-04-12
Technical Paper
2011-01-0194
Pierre Santacreu, Saghi Saedlou, Laurent FAIVRE, Antoine ACHER, Johan Leseux
One way to respect the Euro 5 depollution norm is the downsizing of the engine, which leads to more severe in-use operating conditions especially an increase of the exhaust gas temperature. Consequently, the hot part of the exhaust system, i.e., from manifold to the catalytic converter, could be subjected to maximal temperature up to 1000°C. Moreover, an improved durability and longer life guaranties are also required for such parts. In this context, a new ferritic stainless steel grade has been developed, named K44X (AISI 444, EN 1.4521), which fulfills these new specifications and that could be applied for both fabricated manifold and turbocharger shells. The K44X, with a chromium content of 19% (weight), an addition of 2% molybdenum and 0.6% of niobium, offers excellent high temperature properties like cyclic oxidation, creep and thermal fatigue resistance, a low thermal expansion coefficient.
2011-04-12
Technical Paper
2011-01-0198
Masahiro Fujimoto, Atsushi Fujii, Nobuyuki Matsumiya
Since wear resistance and fatigue strength are key requirements for chassis components, induction hardening is widely used to apply compressive stress for controlling crack growth. Therefore, it is crucial that the influence of defects is examined with compressive residual stress applied to parts. In this report, the relationship between crack depth and compressive residual stress is evaluated using a cylindrical specimen and a torsional fatigue test. The test results were found to be consistent with CAE simulations performed in advance. In the future, it will be necessary to make this method applicable to product design to further improve vehicle safety performance.
2011-04-12
Journal Article
2011-01-0196
Hong Tae Kang, Abolhassan Khosrovaneh, Todd Link, John Bonnen, Mark Amaya, Hua-Chu Shih
Gas Metal Arc Welding (GMAW) is widely employed for joining relatively thick sheet steels in automotive body-in-white structures and frames. The GMAW process is very flexible for various joint geometries and has relatively high welding speed. However, fatigue failures can occur at welded joints subjected to various types of loads. Thus, vehicle design engineers need to understand the fatigue characteristics of welded joints produced by GMAW. Currently, automotive structures employ various advanced high strength steels (AHSS) such as dual-phase (DP) and transformation-induced plasticity (TRIP) steels to produce lighter vehicle structures with improved safety performance and fuel economy, and reduced harmful emissions. Relatively thick gages of AHSS are commonly joined to conventional high strength steels and/or mild steels using GMAW in current body-in-white structures and frames.
2011-04-12
Technical Paper
2011-01-0192
Hong Tae Kang, Abolhassan Khosrovaneh, Mark Amaya, John Bonnen, Hua-Chu Shih, Shahuraj Mane, Todd Link
In the North American automotive industry, various advanced high strength steels (AHSS) are used to lighten vehicle structures, improve safety performance and fuel economy, and reduce harmful emissions. Relatively thick gages of AHSS are commonly joined to conventional high strength steels and/or mild steels using Gas Metal Arc Welding (GMAW) in the current generation body-in-white structures. Additionally, fatigue failures are most likely to occur at joints subjected to a variety of different loadings. It is therefore critical that automotive engineers need to understand the fatigue characteristics of welded joints. The Sheet Steel Fatigue Committee of the Auto/Steel Partnership (A/S-P) completed a comprehensive fatigue study on GMAW joints of both AHSS and conventional sheet steels including: DP590 GA, SAE 1008, HSLA HR 420, DP 600 HR, Boron, DQSK, TRIP 780 GI, and DP780 GI steels.
2011-04-12
Technical Paper
2011-01-0057
Raj Rajendran, Tharanipathy Venkatesan, Rasu Elansezhian
Electroless Nickel (EN) coatings are used in automotive application due to its high hardness, uniform thickness and wear resistance. The study deals with the improvement of surface properties of mild steel by the deposition of Ni-P alloy. The steel specimens were EN coated for various time duration ranging from 0.5 to 3 h. The effect of coating time on thickness, structure, hardness and wear of EN coated steel are investigated. It has been found that the coating thickness is uniform and it increases as the coating time increases. There is no significant change in hardness and wear with increase in coating time. The structure of EN coated steel comprises a surface layer of Ni-P alloy deposit which is instrumental in increase in the hardness. Microhardness of EN coated steel is in the range of 500-540 Hv0.025. The wear rate and coefficient of friction of EN coated steel is found to be low compared to the base metal.
2011-04-12
Journal Article
2011-01-0475
Teresa J. Franklin, Jwo Pan, Michael Santella, Tsung-Yu Pan
Fatigue behavior of dissimilar ultrasonic spot welds in lap-shear specimens of magnesium AZ31B-H24 and hot-dipped-galvanized mild steel sheets is investigated based on experimental observations, closed-form stress intensity factor solutions, and a fatigue life estimation model. Fatigue tests were conducted under different load ranges with two load ratios of 0.1 and 0.2. Optical micrographs of the welds after the tests were examined to understand the failure modes of the welds. The micrographs show that the welds mainly fail from kinked fatigue cracks growing through the magnesium sheets. The optical micrographs also indicate that failure mode changes from the partial nugget pullout mode under low-cycle loading conditions to the transverse crack growth mode under high-cycle loading conditions. The closed-form stress intensity factor solutions at the critical locations of the welds are used to explain the locations of fatigue crack initiation and growth.
2011-04-12
Journal Article
2011-01-0473
Kamran Asim, Kulthida Sripichai, Jwo Pan
In this paper, the fatigue behavior of laser welds in lap-shear specimens of non-galvanized SAE J2340 300Y high strength low alloy (HSLA) steel sheets is investigated based on experimental observations and a fatigue life estimation model. Optical micrographs of the laser welds before and after failure under quasi static and cyclic loading conditions are examined. The micrographs show that the failure modes of laser welds under quasi-static and cyclic loading conditions are quite different. Under quasi-static loading conditions, the weld failure appears to be initiated from the base metal near the boundary of the base metal and the heat affected zone at a distance to the pre-existing crack tip, and the specimens fail due to the necking/shear of the lower left load carrying sheets.
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