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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
2015-01-0526
Timo Faath, Lay Knoerr
In the new ThyssenKrupp InCar®plus project, numerous solutions were developed for body parts and systems that contribute to increased efficiency through the use of new materials and manufacturing technologies. They are superior to current production solutions in terms of weight, cost, performance and sustainability, while also meeting the demand for cost-effective weight reduction. One example is the front bumper: This part offers major weight reduction potential in the front end of the car. Both steel and aluminum versions are currently in serial production. In the ThyssenKrupp InCar®plus project, a highly efficient steel solution was developed that matches the weight level of current aluminum solutions at much lower cost. The hot-formed lightweight steel crash beam is around 20% lighter than conventional steel solutions. The latest safety requirements such as the new R-CAR barrier test and the IIHS Small Overlap Test were taken into account during development.
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
2015-01-1102
Katsuhiko Ohishi, Toshihiro Uehara, Ichirou Kishigami
In recent years, fuel economy improvement of automobiles is required to reduce emissions of carbon dioxide (CO2) which is a greenhouse gas and is well known as one of the factors of global warming. Therefore, continuously variable transmissions (CVT) have been used increasingly, because they are light, compact and contribute to better fuel consumption. Metal belt CVTs are the most popular system in use today. 18mass%Ni maraging steel is used for CVT belts because it has good weldability, good formability and high fatigue strength. Maraging steels strengthened by Ti have high fatigue strength, but TiN particles, which are the main non-metalic inclusions inside steels, might cause fatigue cracks in high cycle regions over 107 cycles. At present there is a special melting process to minimize TiN particle size, but we need further technological innovations to improve fatigue strength.
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
2015-01-0527
Pierre-Olivier Santacreu, Guillaume Badinier, Jean-Benoit Moreau, Jean-Marc Herbelin
A new Ni-free martensitic stainless steel was developed for hot stamped automotive parts, especially in order to design lightweight chassis. After hot stamping simulation, the material exhibits 1.2 GPa ultimate tensile strength with 8% total elongation, in the as-quenched condition (without any tempering treatment). Moreover the material’s chemical composition was optimised 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 behaviour in crash was recorded. To further assess the material’s performance, high cycle and low-cycle fatigue properties of the grade were characterized and the effects of machining and surface were studied. Results show that the fatigue limits at 2 million cycles for a stress ratio of -1 for rough bare surface and shot peened surface are quite high at 0.45 and 0.55 times the ultimate tensile strength (in the range of 540 MPa to 640 MPa).
2015-04-14
Technical Paper
2015-01-1723
Dieter Gabriel, Thomas Hettich
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
Technical Paper
2015-01-0732
Matthew Dula, Heather Eich, Nicole VanBelle, Prasanth Mohankumar, Bryan D. Arnold
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, degreasers of varying type are studied using electrochemical analysis and a correlation is found between the EG steel pitting potential in various degreasers 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
2015-01-0706
Zheng-Ming Su, Pai-Chen Lin, Wei-Jen Lai, Jwo Pan
Failure mode and fatigue behavior of dissimilar laser welds in lap-shear specimens of low carbon steel (LC) and high strength low alloy (HSLA) steel sheets was investigated. Micrographs show that the failure modes of laser welds under quasi-static and cyclic loading conditions were quite different. Under quasi-static loading conditions, the upper sheet was separated at the base metal region. Under low-cycle loading conditions, the weld failure appeared to be initiated from the pre-existing crack tips and then failed by the ductile fracture through the upper right (LC) sheet. Under high-cycle loading conditions, the weld failure appeared to be initiated from the left pre-existing crack tip and then failed by the kinked fatigue crack propagating through the lower left sheets (HSLA). In general, the fatigue lives are longer for the specimens failed through the HSLA steel sheets than those failed through the LC steel sheets.
2015-04-14
Journal Article
2015-01-1482
Bisheshwar Haorongbam, Anindya Deb, Clifford Chou
Hat-sections, single and double, made of steel are frequently encountered in automotive body structural components. These components play a significant role in terms of impact energy absorption during vehicle crashes thereby protecting occupants of vehicles from severe injury. However, with the need for higher fuel economy and for compliance to stringent emission norms, auto manufacturers are looking for means to continually reduce vehicle body weight either by employing lighter materials like aluminum and fiber-reinforced plastics, or by using higher strength steel with reduced gages, or by combinations of these approaches. Unlike steel hat-sections which have been extensively reported in published literature, the axial crushing behavior of hat-sections made of fiber-reinforced composites may not have been adequately probed.
2015-04-14
Journal Article
2015-01-0529
Jody N. Hall, Jason Coryell, Bill Wendt, Donald Adamski
Several production parts have been randomly splitting from trimmed edges even at strains well below the forming limit and hole expansion capabilities of the material. These parts are all Dual Phase (DP) steel with one exception of a multiphase version of a DP980 grade. The fractures were not limited to a specific strength, supplier, or stamping plant. Each part was studied to determine the root cause of failure for each edge fracture and to document the solutions in appropriate standards and specifications. As typical for dual phase steel, the edge fractures involved a stretch condition. However, these fractures are unexpected at such low strains. This paper will review the importance of the trimmed edge condition that must be maintained to eliminate fractures at low strains. A comparison will be made between good and poor trim quality along with an updated specification for a good trimmed edge.
2015-04-14
Technical Paper
2015-01-0531
Hiroyuki Yamashita, Hiroaki Ueno, Hiroyuki Nakai, Takahiro Higaki
Stress relaxation, where stress decreases over time occurs when straining is temporarily stopped during a metal tension test. This is elastic strain becoming plastic strain. We proposed applying stress relaxation to press forming with the aim of strain dispersion. A step motion temporarily stopped the die during forming, and successfully increased the deep draw forming limit. We verified this step motion by a tension test in addition to an actual press-forming test. We concluded that the mechanism increasing the deep draw forming limit is attributed to the dispersion of stress by the step motion, and the effects depended on the stop time and the temperature.
2015-04-14
Journal Article
2015-01-0604
Jibrin Sule, Supriyo Ganguly
In a multi-pass weld, the development of residual stress to a large extent depends on the response of the weld metal, heat affected zone and parent material to complex thermo-mechanical cycles during welding. Most researches used either mechanical tensioning or heat treatment to modified residual stresses in the weld. In this research, creation of a refined and recrystallized microstructure with modified residual stress state was attempted by applying post weld rolling followed by laser processing. The hardening of the weld metal due to multiple pass and subsequently rolling followed by laser processing was evaluated. The residual stress has been investigated non-destructively by using neutron diffraction. Hardness results show evidence of plastic deformation up to 4 mm below the weld surface.
2015-04-14
Journal Article
2015-01-0601
Madhavan Manivannan, Vesselin Stoilov, Derek O. Northwood
Ferritic nitrocarburizing offers excellent wear, scuffing, corrosion and fatigue resistance by producing a thin compound layer containing ε (Fe2-3(C, N)), γ’ (Fe4N), cementite (Fe3C) and various alloy carbides and nitrides on the material surface. It is a widely accepted surface treatment process that results in smaller distortion than carburizing and carbonitriding processes. However this smaller distortion has to be further reduced to prevent the performance issues, out of tolerance distortion and post grinding work hours/cost in an automotive component. A numerical model has been developed to calculate the nitrogen and carbon composition profiles of SAE 1010 torque converter pistons during nitrocarburizing treatment. The nitrogen and carbon composition profiles are modeled against the part thickness and nitrocarburizing time to predict the distortion pattern.
2015-04-14
Journal Article
2015-01-0530
Mikko Joonas Kähkönen, Emmanuel De Moor, John Speer, Grant Thomas
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 compositions. Two step Q&P treatments following full austenitization were conducted using varying partitioning times and a fixed partitioning temperature of 400 °C and the results were compared with literature data for 0.2C 1.5Mn 1.5Si Q&P treated steels. The comparison shows that increasing the carbon content from 0.2 wt pct to 0.4 wt pct increases the ultimate tensile strength by 140 MPa/0.1 wt pct C up to 1610 MPa without significantly decreasing ductility. Increased alloy carbon content did not substantially increase retained austenite fractions. The best combinations of UTS and TE were obtained using short partitioning times.
2015-04-14
Journal Article
2015-01-0528
Armin Abedini, Cliff Butcher, David Anderson, Michael Worswick, Timothy Skszek
The development of stress state dependent fracture surfaces and damage models to predict failure in automotive forming and crash simulations has created great interests in developing experimental tests to characterize failure in constant stress states. The stress state is defined by the three invariants of the stress tensor that are typically expressed in terms of the stress triaxiality and lode parameters. The shear loading condition is critical to the development of the fracture surfaces since it corresponds to the origin of the surface with a stress triaxiality and lode parameter of zero. Numerous types of in-plane shear tests have been proposed in the literature that are suitable to automotive sheet materials with the butterfly-like specimens becoming popular in recent years. The butterfly shear test involves through-thickness machining of the specimen to create a reduced section where fracture will initiate.
2015-04-14
Journal Article
2015-01-0522
Robert Cryderman, Danielle Rickert, Kelly Puzak, John Speer, David Matlock, Michael Burnett
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.
2015-04-14
Journal Article
2015-01-0525
Constantin Chiriac, Ming F. Shi
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
2015-01-0605
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
Journal Article
2015-01-1754
Wei-Jen Lai, Jwo Pan
The analytical stress intensity factor and J integral solutions for welds in lap-shear specimens of two dissimilar sheets are presented in the normalized forms. The analytical solutions were selectively validated by two-dimensional finite element analyses. 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. The transition weld widths for applicable ranges of the weld widths for the analytical solutions based on the beam bending theory are also presented.
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
Technical Paper
2015-01-0554
Rafaa Esmaael, Vernon Fernandez
An accurate prediction of elasto-plastic cyclic deformation becomes extremely important in design optimization. Which lead to a more accurate fatigue life prediction and weight savings. In this project a two-step notch root prediction method based on interpolation between linear and Neuber’s notch strain amplitude solutions is proposed. The accuracy of this method is assessed by comparing the results with the results obtained from elasto-plastic finite element analysis. Different types of steels with different yield strengths were used in this study. Notch deformation behavior under cyclic 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
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
Journal Article
2015-01-0567
Kenji Takada, Kentaro Sato, Ninshu Ma
In order to reduce the automobile body weight and to improve the crashworthiness, the use of high strength steels is greatly increasing these years. An optimal combination of both the crash safety performance and a lightweight structure has been an important challenge in automobile body engineering. The application of high strength steel to automobile body structures has been considered to be an efficient solution because of a lower cost in volume production in the automotive industry. With the improvement of the formability of high strength steels by optimizing the metallic microstructure, the range of applications of high strength steels has been expanding in the automobile body structures. Recently, advanced high strength steels with strength from 980MPa to 1500MPa used in automobile bodies have being playing a crucial role in crash safety performance.
2015-04-14
Journal Article
2015-01-0570
Horst Lanzerath, Markus Tuerk
Tubular designs for the body structure enable a significant weight saving versus the conventional, stamped sheet metal designs. There are several manufacturing processes on the market than can deliver tubular structures, e.g. hydroforming. But currently the processes are limited to material grades up to 1000MPa UTS for body structure parts. Similar to the development in stamping, the target is the have tubular designs available with Ultra High Strength Steel (UHSS) properties (1500MPa) that are known from hot-stamping parts. Within stamping the development was going from Mild Steels (MS) to Advanced High Strength Steels (AHSS) and finally to hot-formed steels with 1500MPa UTS, enabling a significant weight saving potential compared to MS or AHSS. Analogous to this there are some new processes upcoming which are able to produce tubular designs with 1500 MPa strength.
2015-04-14
Technical Paper
2015-01-0584
HaiYan Yu, JiaYi Shen, Gang He
The yield locus of a cold-rolled transformation-induced plasticity (TRIP780) steel sheet was investigated using cruciform biaxial tension. Effect of the key dimensions of the cruciform specimen on the calculation error and stress inhomogeneity was analyzed in detail using orthogonal test combined with finite element analysis. Scan electric metallography (SEM) observations of TRIP780 steel were performed. The theoretical yield curve of TRIP780 steel were calculated with Hill’48, Hill’93, Barlat’89, Gotoh and Hosford yield criteria. Experimental results indicate that none of the selected yield criteria can totally agree with the experimental curve. Among which, Hill’48 and Hosford yield criteria have the largest error while Barlat’89 yield criterion has the smallest error especially near the biaxial tension. Besides Barlat’89 criterion, Hill’93 and Gotoh anisotropic yield criteria are the second choices for TRIP780 steel.
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