Past GDIS™ Presentations

The Inter-Industry Conference on Auto Collision Repair (I-CAR), is a not-for-profit education, knowledge, and solutions organization whose vision is that “Every person in the collision repair industry has the information, knowledge, and skills to perform complete, safe, and quality repairs for the ultimate benefit of the consumer”. As more automakers develop alternative joining methods for attaching various materials, the collision repair industry cannot recreate these joining methods completed at the factory during repairs. Alternative attachment methods designed with available collision repair equipment is crucial to safely restore the vehicle to the original specifications during repair. The collision repair industry’s only source for this information on the correct joining method comes from the OEM engineering departments.

To help the collision repair industry understand these complex repair challenges I-CAR initiated a research project to identify the required information, knowledge, and skills required to restore these vehicles to the OEM specifications that meets crash worthiness design requirements. As we performed this research, we looked at a cross section of the collision repair information available today from various manufacturers. Identifying key pieces of information, tool requirements, techniques, and skills vital to correctly repair these vehicles.

This session provides an opportunity to share the findings of our research with vehicle material engineers, in hopes that as vehicles are being designed and built, the collision repair industry is considered when determining the types of repair information that is needed and how it’s presented to allow for a complete, safe, quality repairs. With the support of material engineers, vehicle makers can adopt the best-in-class repair information for the ultimate benefit of the consumer.

The battery electric vehicle (BEV) enclosure (battery pack) represents an important subsystem. With increased focus on safety, affordability and sustainability of future BEV for mass automotive market, steel offers the best flexibility with solutions to address these key challenges. In this study, using an existing aluminum battery enclosure design as the baseline, a battery enclosure design using advanced high-strength steel (AHSS) is completed which meets all the requirements.

Previously developed coating-free press-hardening steel (CFPHS) had an ultimate tensile strength of about 1.7 GPa and a tensile elongation of 8-9% after hot stamping and simulated paint baking. This combination of strength and ductility, along with its adequate bendability, enables a significant improvement in energy absorption compared to the existing Alsip-coated 22MnB5 grade of 1.5 GPa tensile strength. To investigate potential application beyond a monolithic stamped component, laser welding of the 1.7 GPa coating-free PHS was conducted. Microhardness and tensile properties of the welds were evaluated. Microstructure of the weld seam is also analyzed. Two exemplary applications are explored. The first is a miniaturized door ring of 1:4 scale with similar sheet thickness. The second is a hot air blow formed tubular structure mimicking a hollow twist beam component. In both cases, the weld seam remains crack-free during the hot forming process, and the surface is still shiny which indicates a very thin oxide layer.

A study was performed on the ability to laser weld DP600 material to USIBOR 2000 material using a mode shaping laser. The Alsip coating and as-quenched material properties resulted in numerous defects using conventional fiber lasers that would not meet the quality requirements.

Metallurgical and mechanical testing on coupons with varying gap was performed to validate the process and process window. Additional metallurgical testing was performed on a series a production intent parts to ensure that successful weld could be made in a simulated manufacturing environment.

Using a combination of independent power modulation of the ring and core of the mode shaping laser and beam oscillation with a scanner the quality requirements were achieved. The mode shaping laser was able to achieve the quality requirements by ensuring mixing of the Al from the AlSi coating and controlling the cooling rate of the molten pool.

Automotive manufacturers are faced with the necessity to produce vehicles that have less effect on the environment. The environmental assessment must look at the amount of energy and emissions over the lifecycle of the vehicle and include Production, Use, and End of Life factors. Tools have been developed that enable environmental assessment on a vehicle component basis.

The main structural component of the Bumper System is the front and rear bumper beam. Most automotive bumper beams are manufactured out of steel or aluminum. Steel is the lowest cost material, where aluminum enables mass savings. In the past, the decision to use aluminum bumpers was focused on mass savings only. Decisions based on mass savings consider the energy consumption and CO2 emissions from the Use portion only of the lifecycle assessment and ignore the other two factors of component Production and End of Life.

The University of California – Santa Barbara has developed a life cycle environmental assessment tool which includes all three factors of Production, Use, and End of Life for automotive vehicle applications. This enables vehicle manufacturers to assess steel versus aluminum bumpers with all three factors and make decisions that would lower the impact on the environment. Results have shown steel bumper beams have a favorable environmental impact over aluminum when using this assessment tool.

The failure behavior of resistance spot welds (Button pull-out vs. Interfacial) in ultra-high strength hot stamped steels plays a vital role in overall performance of safety components in automotive body structures. Spot weld failure analysis under shear and normal load is usually performed using standard lap-shear and cross-tension tests which provide some information on the strength and failure mode. However, the standard tests may not be used to investigate through thickness damage progression and failure mechanism due to the fact that failure in spot weld occurs in an enclosed space and cannot be directly observed during the test. In this work, a novel testing geometry design is coupled with digital image correlation technique for in-situ damage analysis of spot welds. The results show the actual sequence of damage progression in spot welds under normal and shear loading for hot-stamped Usibor®1500-AS and Ductibor®1000-AS alloys. Spot welds within the transient softened zone at the fusion boundary fail by Corona debonding, then shearing at the fusion boundary, followed by rapid crack propagation towards the surface. For the interfacial mode, failure is initiated by crack propagation into the fusion zone followed by global shearing.

A microstructure-mapping technique is used to simulate pull-out and interfacial failure using meso-scale finite element methods. The developed models are able to capture failure modes and the predicted force-displacement responses match with the experiments. The simulation results showed that the state of stress for pull-out failure can be much more severe (triaxiality higher than unity), compared to the typical triaxiality range that is used for sheet metal fracture characterization.

Results from a recent Auto/Steel Partnership (A/SP) project were presented on the topic of laser hardening process development for 3 different tool and die materials.

Samples were hardened using D2, TS7 and S2333 (Caldie) die materials which were machined to replicate typical trim and forming die tool finishes. Fraunhofer USA successfully developed a laser process for locally hardening of the trim edges and forming radii of the supplied samples.

A laserline diode laser was used with a specialized zoom optic for adjusting the laser focus spot size in order to further optimize the hardening results for each material type. Pyrometer based process control was used to optimize the heat input consistency during hardening by closed loop control of the laser power to achieve more consistent hardening results.

All 3 materials were successfully hardened and micro hardness measurement results showing sufficient depth and level of hardness increase were presented. Details of new technology recently developed by Fraunhofer IWS in Germany for scanner based laser hardening with Thermal Field Control (TCF) and close loop pyrometer and EMAQS camera based monitoring which will facilitate improved hardening of complex tool geometries were presented.

Mark Mikolaiczik discussed Ford’s 2021 Mustang Mach-E.

Youngtaeck Kim discussed General Motors’ 2021 Chevrolet Trailblazer.

Jeff McCormick discussed General Motors’ 2021 Cadillac Escalade.

Mobility Service providers seek to provide transportation services in densely populated cities that meet customers’ needs for comfort, reliability, safety, and connectivity. Future mobility will be defined by unique powertrains, technologies and architectures that ensure these attributes are met – but there are materials challenges in these designs. Fleet owners must offer products and solutions that also deliver a profitable business model, and the supply chain must deliver on these needs.

This presentation will share details of our newest vehicle program, Steel E-Motive, where we are exploring steel solutions to address Mobility as a Service (MaaS) challenges for fully autonomous and connected electric vehicles. The presentation will showcase the vehicle technical specifications and expectations for steel innovations.

Jeremy Lucas discussed Honda’s 2021 Acura TLX.

There is a growing need to efficiently and accurately characterize next generation advanced high-strength steels (AHSS) 3rd Gen for virtual prototyping and to predict the response of automotive structural components in crash events. The focus of the present study is to consider several 3rd Gen steels of 980 and 1180 MPa strength to develop the experimental test methodologies to efficiently and accurately characterize the material behavior for forming and crash applications. To provide a performance benchmark for the proposed CAE methodology, the geometry, tooling and forming process for a full-size B-pillar for a mid-size SUV were virtually designed in collaboration with Bowman Precision Tooling and Honda R&D Americas. The tooling was then fabricated and the B-pillar forming trials were successful for both 980 and 1180 3rd Gen AHSS with springback after trimming accurately predicted. Assessment of the forming process using a conventional FLC for the 1180 3rd Gen was found to be overly conservative and erroneously predicted significant splitting that did not occur in the forming trials.

Niobium microalloying was originally introduced to dual-phase (DP) steels for the improvement of local and global formability balance through microstructural refinement. Recently developed TRIP-assisted DP steel variants contain retained austenite for enhanced work hardening and provide increased ductility and global formability. Niobium microalloying of these newly developed PD variants, in addition to well-known effects of microstructural refinement, produces a non-trivial strength increment through dispersion of nanometer-sized carbide precipitates in the steel matrix. This study investigates both the microstructural evolution and progress of niobium precipitation during industrial processing of a TRIP-assisted DP 980 steel in which an intermediate batch annealing process is employed to optimize precipitate influence on recrystallization kinetics. Remarkable reductions in structural heterogeneity are observed between the hot rolled and final products. These observations are interpreted considering the solubility and precipitation kinetics of niobium. Pronounced refinement of the cold rolled and annealed TRIP-assisted DP microstructure is observed due to a strong recrystallization delay of the cold rolled ferrite matrix by niobium carbide precipitates in the final annealing cycle. The influences of associated microstructural characteristics on strength and formability are elucidated.

The VDA 238-100 tight-radius bend test provides excellent plane-strain conditions for fracture characterization and has proven to be valuable for material ranking and selection for forming and crash applications where material folding is paramount for energy absorption. The custom inverted V-Bend test frame at the University of Waterloo facilitates full-field DIC strain measurements and thus provides failure strains for calibration of fracture models in addition to the conventional bend angle. The VDA specification recommends the use of a load threshold for unique identification of material failure that has been found to systematically underpredict the performance of many grades of automotive steel. Three simple alternative methodologies for fracture detection are proposed based upon: the bending moment, nominal principal stress, and the strain rate for a range of representative automotive steels. The novel fracture detection methodologies were evaluated for seven automotive steels with strength levels from 270 to 1500 MPa that included hot-stamped, third generation advanced high strength, dual phase, and mild steels. The proposed metrics for fracture detection can be readily implemented using the current test data available in the VDA test to efficiently and accurately characterize bend performance for forming and crash.

The purpose of this study is to investigate the effects of both steel gauge and punch radius on the bend performance metrics in three point bending. Current sharp-radius bend test methodologies, e.g., VDA238-100, will be evaluated and compared to proposed bend test variants to determine testing parameters that provide maximum test result delineation for crashworthiness evaluation. Results of focus will be peak load, bending angle at peak load, pre- and post-peak energy absorption, and total energy absorption. Additionally, the effects of steel gauge on the above-mentioned properties will be evaluated to determine expected variation for specification development. Correlation to component level testing may be performed as a secondary task to verify applicability of sharp radius three-point bending for crashworthiness evaluation.

3rd Gen advanced high-strength steel (AHSS) are extensively considered for usage in Body-In-White (BIW) with lower thickness to reduce the vehicle weight and increase fuel efficiency. To improve strength and ductility in 3rd Gen. AHSS, the materials design concept can be different from Gen 1 and Gen 2 AHSS. Hence, it is necessary for the automotive industry to evaluate these materials properly for manufacturing. Resistance spot welding (RSW) continues to be a major joining process in BIW, and that is common for 3rd Gen AHSS as well.

Liquid metal embrittlement (LME) has been recognized as one of phenomena sometimes observed during welding. However, LME depends on several factors, but not only materials design but also welding condition and industrial noise factor. In Auto/Steel Partnership (A/SP), it has been aimed to understand LME behavior using Gleeble to find the proper temperature and deformation is required to form LME. A/SP has conducted a deep investigation to develop a procedure Gleeble procedure and analyzing of data for LME susceptibility level. In continuity of this effort, A/SP has developed a more lab based RSW protocol for LME evaluation which can be used for LME level evaluation of 3rd Gen AHSS. In meantime, to minimizing LME through welding parameters, the effect of different welding parameters is investigated.

To complete the loop for fully understanding the post-weld performance of 3rd Gen. AHSS in design, A/SP also investigate on weld performance during quasi-static and dynamic, through different type of mechanical tests, and a short overview will be presented.

Resistance spot welding (RSW) is the most common joining process in car body manufacturing and is frequently used to join components made of advanced high-strength steels (AHSS). These steels are typically applied with a zinc coating to improve their resistance against corrosion. During the RSW-process liquefied zinc can infiltrate the grain boundaries of the steel substrate, causing a phenomenon referred to as liquid metal embrittlement (LME). In cases where LME is especially severe, joint performance might be affected; therefore, prevention or mitigation of LME is desirable.

This study investigates methods suitable for the practical avoidance of liquid metal embrittlement during the resistance spot welding of AHSS. At first, the effect of an electrode geometry variation is investigated by utilizing a progressively elongated weld time. Occurring effects are analyzed in detail and correlated with a FE-simulation to generate a better understanding of the mechanisms causing LME in RSW. The importance of adapted hold-times depending on the welding boundary conditions is shown and the general effect of excessive energy input by high weld currents and elongated weld times is discussed. Finally, the robustness of the proposed methods is validated in a more complex welding scenario.