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2015-09-14 ...
  • September 14-15, 2015 (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.
2015-04-22
Event
This symposium provides a forum for researchers and application engineers to disseminate the knowledge and information gained in the area of advanced high-strength and press-hardening steel development and applications in automotive structures, enabling light-weight and durable vehicles with improved safety.
2015-04-22
Event
This symposium provides a forum for researchers and application engineers to disseminate the knowledge and information gained in the area of advanced high-strength and press-hardening steel development and applications in automotive structures, enabling light-weight and durable vehicles with improved safety.
2015-04-20 ...
  • April 20-21, 2015 (8:30 a.m. - 4:30 p.m.) - Detroit, Michigan
  • October 29-30, 2015 (8:30 a.m. - 4:30 p.m.) - Troy, Michigan
Training / Education Classroom Seminars
Attendees to the seminars held in conjunction with the SAE 2015 World Congress will receive COMPLETE access to Congress activities for only $55 per day. If interested, please contact our Customer Service department at +1.877.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S. and Canada) to register for this special Congress daily rate. Preventing future problems and troubleshooting existing problems in today's stamping plants requires greater stamping process knowledge. The link between inputs and outputs isn't as clear as many think, increasing the need for detailed understanding of the variables involved.
2015-04-14
Technical Paper
2015-01-0705
Koichi Taniguchi, Hiroshi Matsuda, Rinsei Ikeda, Kenji Oi
High joint strength of resistance spot welds is necessary for high rigidity and reliability of car body using ultra high strength steel (UHSS) sheets with tensile strength over 980MPa. We developed “pulsed current pattern” consisting the combination of short cool time and short-time high-current post-heating. This new process can achieve high cross tension strength (CTS) with sufficient tensile shear strength (TSS) in shorter welding time than conventional temper pattern. This paper presents the heating pattern and the effect on the joint strength by pulsed current pattern. Finite element analysis (FEA) for post-heating patterns was conducted using SORPAS. Temperature dependent material properties of 1180MPa grade steel were taken into account. FEA shows that the short-time high-current post-heating leads to rapid heating in nugget and heat affected zone (HAZ) compared to conventional temper pattern consisting long-time low-current post-heating.
2015-04-14
Technical Paper
2015-01-0531
Hiroyuki Yamashita, Hiroaki Ueno, Hiroyuki Nakai, Takahiro Higaki
Abstract When the strain is temporarily stopped during tensile testing of a metal, a stress relaxation phenomenon is known to occur whereby the stress diminishes with the passage of time. This phenomenon has been explained as the change of elastic strain into plastic strain. A technique was devised for deliberately causing strain dispersion to occur by applying the stress relaxation phenomenon during stamping. A new step motion that pause the die during forming was devised; it succeeded in modifying the deep-draw forming limit by a maximum of 40%. This new technique was verified through tensile and actual stamping tests. It was confirmed that the use of step motion causes the strain to disperse, thereby modifying the deep draw forming limit. The degree to which the forming limit is modified is dependent on the stop time and the temperature.
2015-04-14
Technical Paper
2015-01-1347
Fiona Ruel, Pierre-Olivier Santacreu, Saghi Saedlou, Guillaume Badinier, Jean Herbelin
In order to meet new environmental regulations (i.e. mass of CO2 rejected in the atmosphere per km), car manufacturers are looking for new solutions to lighten chassis and structural parts in cars. High strength steels formed by hot stamping have proved to be good candidates for achieving better in-use performances together with a lighter structure. In particular, our martensitic stainless steel MaX fulfils the industrial targets for chassis parts in terms of mechanical and fatigue properties which could potentially lead to a 15% to 20% weight saving. However, those parts are often made of a complex assembly of different materials (high strength steels, aluminium and cast iron among others) which are subjected to aggressive environments in service. Therefore galvanic corrosion of those complex assemblies has to be evaluated.
2015-04-14
Technical Paper
2015-01-0732
Matthew Dula, Heather Eich, Nicole VanBelle, Prasanth Mohankumar, Bryan D. Arnold
Abstract A surface phenomenon associated with the localized excessive growth of phosphate crystals on electrogalvanized (EG) steel is investigated. The excessive phosphate growth (i.e., “nubbing”) is found to correspond to pitting of the EG zinc coating during the degreasing process. In an industry first, alkaline degreasers of varying type are studied using electrochemical analysis and a correlation is found between the EG steel pitting potential and nubbing severity of pre-treated EG steel. Electrochemical analysis of lab-prepared degreaser samples confirms that degreaser pH is primarily responsible for pitting severity. Pretreatment parameter changes are discussed as being able to prevent such a phenomenon.
2015-04-14
Technical Paper
2015-01-1102
Katsuhiko Ohishi, Toshihiro Uehara, Ichirou Kishigami
Abstract High fatigue strength is required for maraging steel for CVT belts. Two types of next generation maraging steels for CVT belts were studied using the following conditions, (a) increasing tensile strength, (b) increasing compressive residual stress on the nitrided surface, and (c) no addition of Ti. AlloyB (Fe-19%Ni-5%Co-5%Mo-1%Cr-0.8∼1.5%Al, %=mass%) with low Co and AlloyC (Fe-19%Ni-12.5%Co-5%Mo-0.5∼1%Cr,%=mass%) with high Co, were developed by additions of optimized amounts of Al and Cr, which are based on different strengthening ideas of Ti addition. These maraging steels showed tensile strengths and fatigue strengths equal to or better than those of conventional Ti-containing maraging steels.
2015-04-14
Technical Paper
2015-01-0565
Thomas Kurz, Gerald Luckeneder, Thomas Manzenreiter, Harald Schwinghammer, Andreas Sommer
Press-hardening steels get more and more popular for body in white applications as an approach to meet the demands of passenger safety and CO2 reduction. Unlike the larger part of the structure that is typically zinc coated the majority of the PHS parts is either uncoated or aluminum silicon coated. This paper shall give an overview of press-hardening steels with zinc coatings with detailed results for corrosion resistance, weldability and mechanical properties for strength levels of 490 to 1800 MPa. Furthermore as for zinc coated material maintaining a robust press-hardening process is of even higher importance than for uncoated or AlSi coated material, a range of different processes including indirect and direct process are shown in detail. Especially the topic of micro-cracks, mechanisms and avoidance in the direct process will be discussed. Results from industrial and semi industrial production are shown.
2015-04-14
Technical Paper
2015-01-0526
Timo Faath, Lay Knoerr
Abstract In the new ThyssenKrupp InCar®plus project, numerous solutions were developed for vehicle components and systems that contribute to increased efficiency through the use of new materials and advanced manufacturing technologies. These solutions are superior to current production applications in terms of weight, cost, performance and sustainability, while also meeting the demand for cost-effective weight reduction. This paper features structural components solutions focusing on Bumpers, and A- and B-pillars which overall attained between 8% to 19% weight reduction compared to their significant reference parts by incorporating flexible design concepts, progressive new materials, virtual analyses, and innovative manufacturing processes that have been tested and validated along the entire value chain. The prototypes developed were subjected to stringent safety assessments.
2015-04-14
Technical Paper
2015-01-0459
Vesna Savic, Louis Hector, Hesham Ezzat, Anil Sachdev, James Quinn, Ronald Krupitzer, Xin Sun
This paper presents an overview of a four-year project on integrated computational materials engineering (ICME) for third generation advanced high-strength steels (3GAHSS) development. Following a brief look at ICME as an emerging discipline within the Materials Genome Initiative, technical tasks in the ICME project will be discussed. Specific focus of the individual tasks is on multi-scale, microstructure-based material model development using state-of-the-art computational and experimental techniques, forming, assembly, design optimization, integration and technical cost modeling. The integrated approach is illustrated using a 980 grade transformation induced plasticity (TRIP) steel with a two-step quenching and partitioning (Q&P) heat treatment as an example.
2015-04-14
Technical Paper
2015-01-0527
Pierre-Olivier Santacreu, Guillaume Badinier, Jean-Benoit Moreau, Jean-Marc Herbelin
Abstract A new Ni-free martensitic stainless steel (MSS) was developed for hot stamped automotive parts, especially in order to design lightweight chassis part. After hot stamping simulation, the material exhibited a 1.2 GPa ultimate tensile strength with a minimum of 10% total elongation, in the as-quenched condition (Q) without any tempering treatment (Q+T). Moreover the material's chemical composition was optimized to improve the ductility at low temperature and during high strain rate mechanical testing. As a result, no brittle fracture in impact testing at −40°C was observed, and a good behavior in crash was recorded. To further assess the material's performances, high cycle fatigue properties of the grade have been characterized including the effects of machining and surface treatments. Results show that the fatigue limits at 2 million cycles for a stress ratio of −1, for both bare and shot peened surface are quite high and in the range of 580 MPa to 640 MPa.
2015-04-14
Technical Paper
2015-01-0554
Rafaa Esmaael, Vernon Fernandez
An accurate prediction of elasto-plastic cyclic deformation becomes extremely important in design optimization. It also leads to more accurate fatigue life prediction and hence weight savings. In paper presents a two-stage notch root prediction method. This is based on a correction expression to Neuber's rule notch strain amplitude as the first stage, and a linear interpolation scheme as the second stage. The accuracy of this method is assessed by comparing the predicted results with the results obtained from elasto-plastic finite element analysis. Various types of steels with different yield strengths were used in this study. Notch deformation behavior under cyclic variable amplitude loading conditions was monitored for a double notched flat plate and a circumference notched round bar to cover plain stress and plain strain conditions. Elastic as well as elasto-plastic finite element analyses are performed.
2015-04-14
Journal Article
2015-01-0605
Guoyu Yang, Scott Kish
Abstract Heavy stamping parts of HSLA (high strength low alloy) steel are widely used in the automotive industry for design optimization. The material properties of the heavy stamping parts however, change during the stamping process, making simulation and analysis difficult. Traditional tensile tests, used to obtain the material properties, might not be applicable due to the size of specimens required. Without reliable material properties, it is very hard for FEA simulations to predict accurate results. A method for characterizing the material properties of a heavy stamped steel part was presented in this paper. Based on monotonic and fatigue test results, gathered in cooperation with The University of Toledo, we developed specific material models for strength and fatigue analysis. Instead of employing commercial fatigue analysis software, we can perform the fatigue life prediction by using traditional static analysis in ABAQUS with more accurate results.
2015-04-14
Journal Article
2015-01-0730
Tsutomu Miyadera
Austenitic stainless steel was selected as the type of steel to be used to comply with the LEV II regulations. The fuel filler pipe requires a layout in which it is not subject to chipping or the addition of accessories like anti-chipping covers, which represented an additional cost-increasing factor. This research examined a variety of pretreatments in an attempt to increase the adhesiveness of coating to stainless steel. Wood’s Nickel Strike plating displays good adhesiveness to stainless steel, and the addition of Wood’s Nickel Strike plating to stainless steel parts helped to eliminate the tough oxide films that form on stainless steel and to prevent the films from reforming. A cation electrodeposition coating was applied to this Wood’s Nickel Strike plating, and extremely good adhesiveness between the coating and the plating was achieved without having to apply any additional films to boost adhesiveness of the coating.
2015-04-14
Journal Article
2015-01-0734
Yasuhiko Saijo, Mitsuhiko Ueki, Hirokazu Watanabe, Yoichiro Tejima
We need to have knowledge of corrosion environments that vehicles encounter to evaluate the rust prevention performance of new structures and materials during the automotive development process. Accelerated corrosion tests are conducted to predict the lifespan of materials where no market data is available, and it is important to realize a correlation between these tests and corrosion behavior. The purpose of the research discussed in this paper was to quantify automotive corrosion environments to help ensure a correlation between corrosion tests and market environments and predict the lifespan of materials, resulting in the determination of optimal anti-rust specifications. A technology to monitor automotive corrosion environments was developed using a sensor to detect the rust reduction current.
2015-04-14
Technical Paper
2015-01-1723
Dieter Gabriel, Thomas Hettich
Abstract Fuel economy legislation is requiring further improvements to piston friction reduction as well as additional gains in thermal efficiency. A piston material change from aluminum to steel is enabling advancements in both demands. Furthermore, steel material properties lead to increased piston strength, robustness and durability. All this can be achieved at a lower compression height compared to an aluminum reference piston. Therefore, piston mass can be reduced despite the increase in material density. Since steel pistons require cooling of the combustion bowl region and the ring belt just like the aluminum counterpart, MAHLE implemented a new innovative metal joining technology by using laser welding to generate a cooling gallery. The TopWeld® concept offers design flexibility which cannot be matched by any other welding process.
2015-04-14
Journal Article
2015-01-1754
Wei-Jen Lai, Jwo Pan
Abstract In this paper, the analytical stress intensity factor and J integral solutions for welds in lap-shear specimens of two dissimilar sheets based on the beam bending theory are first reviewed. The solutions are then presented in the normalized forms. Next, two-dimensional finite element analyses were selectively conducted to validate the analytical solutions based on the beam bending theory. The interface crack parameters, the stress intensity factor solutions, and the J integral solutions for welds in lap-shear specimens of different combinations of steel, aluminum, and magnesium, and the combination of aluminum and copper sheets of different thickness ratios are then presented for convenient fracture and fatigue analyses. The transition thickness ratios for critical crack locations for different combinations of dissimilar materials are then determined from the analytical solutions.
2015-04-14
Technical Paper
2015-01-0408
Jeff Conklin, Randy Beals, Zach Brown
Vehma / Cosma Engineering International, the U.S. Department of Energy and Ford Motor Company initiated the Multi Materials Lightweight Vehicle (MMLV) Project in 2012. The goal of producing a multi-material vehicle, approximately 25% mass reduction relative to the baseline has been achieved. This paper reviews the mass reduction and structural performance of aluminum high pressure vacuum die cast (hpvdc) applications for a lightweight, multi-material body in white (BIW) relative to a C/D segment production vehicle. Selected stiffness, durability and crash requirements are assessed. The structure incorporates aluminum castings, extrusions and sheet as well as steel sheet, assembled using structural adhesive bonding and a variety of joining technologies. No other body structure in high volume production incorporates this combination of materials and joining processes.
2015-04-14
Journal Article
2015-01-0519
Susumu Maeda, Atsushi Kobayashi, Yuichiro Shimizu, Masao Kanayama, Masato Yuya, Hideki Imataka
Abstract A new nitriding technology and material technology have been developed to increase the strength of microalloyed gears. The developed nitriding technology makes it possible to freely select the phase composition of the nitride compound layer by controlling the treatment atmosphere. The treatment environment is controlled to exclude sources of supply of [C], and H2 is applied as the carrier gas. This has made it possible to control the forward reaction that decomposes NH3, helping to enable the stable precipitation of γ′-phase, which offers excellent peeling resistance. A material optimized for the new nitriding technology was also developed. The new material is a low-carbon alloy steel that makes it possible to minimize the difference in hardness between the compound layer and the substrate directly below it, and is resistant to decline in internal hardness due to aging precipitation in the temperature range used in the nitriding treatment.
2015-04-14
Journal Article
2015-01-0529
Jody N. Hall, Jason Coryell, Bill Wendt, Donald Adamski
Abstract With the implementation of Advanced High Strength Steel (AHSS) becoming more common for automotive manufacturers to reduce mass and/or improve performance, special stamping considerations must be made. Certain production parts may split at trimmed edges where strain levels are well below the forming limit curve of the respective grade, which is more applicable to necking fractures/splits. Similar to the presence of hard inclusion stringers (i.e. MnS) that can cause edge fractures in high strength low alloy steels, AHSS steels most susceptible to this phenomenon typically consist of dual phase or multiphase microstructures containing both a hard phase (martensite) and a soft phase (ferrite). Specific examples of these parts will be discussed, including studies to determine the root cause of the edge fracture and to communicate the solutions for consideration in appropriate standards and specifications.
2015-04-14
Journal Article
2015-01-0530
Mikko Joonas Kähkönen, Emmanuel De Moor, John Speer, Grant Thomas
Abstract Quenching and partitioning (Q&P) is a novel heat treatment to produce third generation advanced high-strength steels (AHSS). The influence of carbon on mechanical properties of Q&P treated CMnSi-steels was studied using 0.3C-1.5Mn-1.5Si and 0.4C-1.5Mn-1.5Si alloys. Full austenitization followed by two-step Q&P treatments were conducted using varying partitioning times and a fixed partitioning temperature of 400 °C. The results were compared to literature data for 0.2C-1.6Mn-1.6Si, 0.2-3Mn-1.6Si and 0.3-3Mn-1.6Si Q&P treated steels. The comparison showed that increasing the carbon content from 0.2 to 0.4 wt pct increased the ultimate tensile strength by 140 MPa per 0.1 wt pct C up to 1611 MPa without significantly decreasing ductility for the partitioning conditions used. Increased alloy carbon content did not substantially increase the retained austenite fractions.
2015-04-14
Journal Article
2015-01-0525
Constantin Chiriac, Ming F. Shi
Abstract Automotive structural parts made out of Advanced High Strength Steel (AHSS) are often produced in a multistage forming process using progressive dies or transfer dies. During each forming stage the steel is subjected to work hardening, which affects the formability of the steel in the subsequent forming operation. Edge flanging and in-plane edge stretching operations are forming modes that are typically employed in the last stage of the multistage forming processes. In this study, the multistage forming process was simulated by pre-straining a DP980 steel in a biaxial strain path with various strain levels followed by edge flanging and in-plane edge stretching. The biaxial prestrains were obtained using the Marciniak stretch test and edge flanging and in-plane edge stretching were accomplished by the hole expansion test using a flat punch and a conical punch, respectively.
2015-04-14
Journal Article
2015-01-0528
Armin Abedini, Cliff Butcher, David Anderson, Michael Worswick, Timothy Skszek
Abstract Two different shear sample geometries were employed to investigate the elastoplastic and failure behaviour of three automotive alloy rolled sheets; a highly anisotropic magnesium alloy (ZEK100) and two relatively isotropic dual phase steels (DP600 and DP780). The performance of the so-called butterfly type specimen (Mohr and Henn 2007, Dunand and Mohr 2011) was evaluated at quasi-static conditions along with the shear geometry of Peirs et al. (2012) using in situ 3-D digital image correlation (DIC) strain measurement techniques. It was shown that both test geometries resulted in similar trends of the load-displacement response; however, the fracture strains obtained using the butterfly specimen were lower for the ZEK100 and DP780. It was demonstrated that the ZEK100 exhibits strong anisotropy in terms of the shear work hardening rate and failure strain.
2015-04-14
Journal Article
2015-01-0522
Robert Cryderman, Danielle Rickert, Kelly Puzak, John Speer, David Matlock, Michael Burnett
Abstract Fracture split forged steel connecting rods are utilized in many new high performance automotive engines to increase durability. Higher strength levels are needed as the power density increases. Fracture splitting without plastic deformation is necessary for manufacturability. Metallurgical design is a key for achieving the required performance levels. Several medium carbon steels containing 0.07 wt pct P, 0.06 wt pct S and various amounts of Mn, Si, V, and N were produced by vacuum induction melting laboratory heats and hot working the cast ingots into plates. The plates were cooled at varying rates to simulate typical cooling methods after forging. Microstructures were generally ferrite and pearlite as evaluated by light optical and scanning electron microscopy. Mechanical properties were determined by standard tensile tests, high strain rate notched tensile tests, and Charpy V-notch impact tests to assess “splittability”.
2015-04-14
Journal Article
2015-01-0570
Horst Lanzerath, Markus Tuerk
Abstract Hot-formed steels, also called “Boron steels” or Ultra-High Strength Steels-UHSS, offer a great weight saving potential versus conventional cold-formed high strength steels used for crash relevant structural parts. Boron steels allow complex shaped parts due to the hot-forming process. In the hot forming process first the sheet metal with initial yield strength of around σy=400 MPa is blanked and then heated in an oven up to ∼950° Celsius. In the next step the “hot” sheet metal is stamped and at the same time rapidly cooled down and quench hardened in the stamping die. During this process the yield and ultimate tensile strength increase up to approximately σy>1100 MPa and UTS∼1500 MPa in the final stamped part. The enormous strength and the very good dimensional tolerances with nearly no springback result in the use of more and more hot-formed parts in the body, especially for crash relevant parts like structural reinforcements.
2015-04-14
Journal Article
2015-01-0567
Kenji Takada, Kentaro Sato, Ninshu Ma
Abstract In order to reduce automobile body weight and improve crashworthiness, the use of high-strength steels has increased greatly in recent years. An optimal combination of both crash safety performance and lightweight structure has been a major challenge in automobile body engineering. In this study, the Cockcroft-Latham fracture criterion was applied to predict the fracture of high-strength steels. Marciniak-type biaxial stretching tests for high-strength steels were performed to measure the material constant of the Cockcroft-Latham fracture criterion. Furthermore, in order to improve the simulation accuracy, local anisotropic parameters based on the plastic strain (strain dependent model of anisotropy) were measured using the digital image grid method and were incorporated into Hill's anisotropic yield condition by the authors. In order to confirm the validity of the Cockcroft-Latham fracture criterion, uniaxial tensile tests were performed.
2015-04-14
Technical Paper
2015-01-0584
HaiYan Yu, JiaYi Shen, Gang He
Abstract The yield locus of a cold-rolled transformation-induced plasticity (TRIP780) steel sheet was investigated using a biaxial tensile test on a cruciform specimen. The effect of the key dimensions of the cruciform specimen on the calculation error and stress inhomogeneity was analyzed in detail using an orthogonal test combined with a finite element analysis. Scanning electron metallography (SEM) observations of the TRIP780 steel were performed. The yield curve of the TRIP780 steel was also calculated using the Von Mises, Hill '48, Hill '93, Barlat '89, Gotoh and Hosford yield criteria. The experimental results indicate that none of the selected yield criteria completely agree with the experimental curve. The Hill '48 and Hosford yield criteria have the largest error while the Hill '93 and Gotoh yield criteria have the smallest error.
2015-04-14
Journal Article
2015-01-0706
Zheng-Ming Su, Pai-Chen Lin, Wei-Jen Lai, Jwo Pan
Abstract In this paper, failure modes of dissimilar laser welds in lap-shear specimens of low carbon steel and high strength low alloy (HSLA) steel sheets are investigated based on experimental observations. Micro-hardness tests across the weld zones of dissimilar laser welds were conducted. The hardness values of the fusion zones and heat affected zones are significantly higher than those of the base metals. The fatigue lives and the corresponding failure modes of laser welds as functions of the load ranges are then examined. Optical micrographs of the laser welds before and after failure under quasi-static and cyclic loading conditions are then examined. The failure modes and fatigue behaviors of the laser welds under different loading conditions are different. Under quasi-static loading conditions, a necking failure occurred in the upper low carbon steel sheet far away from the laser weld.
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