Current Vehicle Examples

Current Vehicle Examples

Manufacturers embrace Advanced High Strength Steels as a cost-effective way to satisfy functional and regulatory requirements. The following are just a few examples where automakers have attributed improved performance and lightweighting due to the use of these advanced steels.

KIA EV9

The Kia EV9, Kia’s first three-row electric flagship SUV, is based on the Electric Global Modular Platform (E-GMP).K-59 Kia EV9 won the 2024 North American Utility Vehicle of the Year™ (NACTOY) AwardK-60, and was named a 2024 Top Safety Pick by IIHS, the Insurance Institute for Highway Safety.K-61 Kia deployed hot stamped parts in the passenger safety cage for enhanced passenger protection and crash energy management.K-62

Figure 1: Hot stamped parts increase the average tensile strength in the 2024 Kia EV9K-62

 

Tesla Cybertruck and Model Y

Much press has been given to the “ultra-hard stainless steel” used on the Cybertruck skin panelsT-46, but there are several high strength and advanced high strength steel parts on the vehicle as well. According to the Cybertruck Collision Repair Manual,T-47 Tesla defines mild steel as having a tensile strength less than 270 MPa. The tensile strength of high strength steels ranges from 300 MPa to 700 MPa. Ultra high strength steels are those with a tensile strength greater than 800 MPa.  Figure 2 presents a breakdown of materials used in the body structure.

 

Figure 2: Cybertruck Body Materials. Dark blue = mild steel; yellow = high strength steel; red = ultra high strength steel; orange = stainless steel.T-47

 

A video by Munro Live with Lars Moravy, Tesla’s Head of Vehicle Engineering, shows that the Cybertruck body side inner is formed from a laser welded press hardened steel.M-65-2  An interview with Thomas Ausmann, former global advanced manufacturing technical advisor at Tesla, confirms that Tesla hot stamps the double-door rings, which represents the first hot-stamped part that Tesla had ever produced internally at any of its plants.B-78 Figure 3 shows a Cybertruck hot-stamped body side inner.

Figure 3: The Cybertruck double door ring made from a laser welded blank is the first hot stamped part that Tesla ever produced internally at any of its plants M-65-2 B-78

The Model Y Collision Repair Procedures ManualT-48 highlights that there are several ultra high strength steel parts in the body structure.   Another video from Munro LiveM-70 confirms that the ultra high strength steel in the body side aperture is press hardened, hot stamped steel.  Simwon NA is the likely supplier of these hot stamped parts.Y-15

Figure 4: Press Hardened Hot Stamped Steel in the Model Y Body Side Outers and Inners. Dark blue = mild steel; yellow = high strength steel; red = ultra high strength steelT-48

Li Auto L8

The Li L8 is a luxury range-extended battery electric SUV equipped with an autonomous driving system produced by Chinese manufacturer Li Auto.  Hot-formed steel is used in safety-critical areas such as the A-pillar, B-pillar, C-pillar, door sills, and door intrusion beams, accounting for 28.9% of the entire body-in-white, with high strength steels accounting for over 75% of the body structure. Hot-formed steel parts are shown in red in Figure 5, with ultra high strength steel shown in yellow, high strength steel shown in dark gray, and mild steel parts colored in blue.X-2

Figure 5: Nearly 30% of the Li Auto L8 body-in-white is made from Hot Stamped Press Hardened Steels.X-2



Honda Civic

The 2025 Honda Civic Hybrid, based on the 11th Generation Honda Civic platform launched for the 2022 model year, uses high strength and advanced high strength steel throughout their Next-Generation Advanced Compatibility Engineering™ (ACE™) body structure.  Honda defines high-strength steel (HSS) as any steel with a tensile strength of 340 MPa or higher.  Ultra-high-strength steels (UHSS) are those with a tensile strength of 980 MPa or higher.H-68

Figure 6: The body construction of the 2025 Honda Civic uses high-strength steel and advanced high-strength steel for enhanced passenger protection.H-67

Nissan Rogue

The 3rd Generation Nissan Rogue, launched for the 2021 Model Year, makes extensive use of advanced high strength steels, including 3rd Gen AHSS.

Nissan deploys AHSS grades for 35% of the body structure, an increase of more than 10% compared to the prior version.L-67  Hot stamped press hardened steels, not used in the prior model, helps this Nissan Rogue achieve improved safety, fuel efficiency, and customer satisfaction.  Figure 7 shows how various steel grades are deployed in the body structure.

Figure 7: Nissan Rogue Body-in-White Uses Press Hardened Steels and 3rd Generation Advanced High Strength Steel Grades.L-67

The Rogue’s B-pillar is cold stamped from a tailor welded blank of super high formable 980 (SHF 980) and super high formable 1180 (SHF 1180) steel, allowing Nissan to realize the same benefits of hot stamping at a much higher productivity, as highlighted in Figure 8 L-67. Both of these super high formable grades can be considered 3rd Generation Advanced High Strength Steels. (See the information on the 2018 Infinity QX50 SUV here) .

Figure 8: The Nissan Rogue uses a laser welded blank formed from two 3rd Generation Advanced High Strength Steels. L-67

A critical enabling technology in the use of SHF 980 and SHF 1180 is the development of design guidelines for welding stacks that include those materials. These guidelines use weld gun control and panel positioning to prevent unneeded additional tensile stress in the weld stack.L-66  Minimizing the tensile stress in the weld stack helps address the risk of liquid metal embrittlement as does extending the hold time portion of the spot weld cycle in order to lower the temperature prior to releasing the electrodes.L-67 

Chevrolet Blazer EV

The Chevrolet Blazer EV is built on the same architecture as the Chevrolet Equinox EV, Cadillac Lyriq, Honda Prologue, Acura ZDX EV, among others.E-14

Fifteen percent of the body structure are ultra high strength steels, including multiphase, martensitic, and 3rd Generation Steels having a tensile strength of at least 980 MPa. An additional 11% are stamped from press hardened steels. The breakdown of the Blazer EV body structure is shown in Figure 9.

Regarding the battery pack, part of the General Motors battery management system known as the Rechargeable Energy Storage System (RESS), 43% of the all-steel construction is made from grades with tensile strength of at least 980 MPa. (Figure 10).

Instead of using press hardening steels for the B-pillar, General Motors stated that there was a cost savings in addition to a mass savings by using 3rd Generation AHSS in this application. This required development of a material grade specification capable of use globally, along with forming and welding practices for robust production. (Figure 11).

Figure 9: 35% of the Chevrolet Blazer EV body structure is made from Advanced High Strength Steels with a tensile strength of at least 590 MPa. E-14

 

Figure 10: 43% of the Chevrolet Blazer EV Rechargeable Energy Storage System structure is made from Advanced High Strength Steels with a tensile strength of at least 980 MPa. E-14

 

Figure 11: Use of 3rd Generation Advanced High Strength Steels in the B-Pillar of the Chevrolet Blazer EV led to cost savings and mass savings while maintaining crash and safety performance. E-14

 

 

The Need for Powertrain Models

The Need for Powertrain Models

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Dr. Donald Malen, College of Engineering, University of Michigan, reviews the use of two recently developed Powertrain Models, which he co-authored with Dr. Roland Geyer, University of California, Bren School of Environmental Science.

The use of Advanced High-Strength Steel (AHSS) grades offer a means to lightweight a vehicle. Among the benefits of this lightweighting are less fuel used over the vehicle life, and better acceleration performance. Vehicle designers as well as Greenhouse Gas analysts are interested in estimating these benefits early in the vehicle design process. G-13

Models are constructed for this purpose which range from the use of a simple coefficient, (for example fuel consumption change per kg of mass reduction), to very detailed models accessible only to specialists which require knowledge of hundreds of vehicle parameters. Draw backs to the first approach is that the coefficient may be based on assumptions about the vehicle which do not match the current case. Drawbacks to the detailed models are the considerable expense and time needed, and the lack of transparency in the results; It is difficult to relate inputs with outputs.
A middle way between the simplistic coefficient and the complex model, is described here as a set of Parsimonious Powertrain Models. G-10, G-11, G-12  Parsimony is the principle that the best model is the one that requires the fewest assumptions while still providing adequate estimates. These Excel spreadsheet models cover Internal Combustion powertrains, Battery Electric Vehicles, and Plug-in Electric Vehicles, and predict fuel consumption and acceleration performance based on a small set of inputs. Inputs include vehicle characteristics (mass, drag coefficient, frontal area, rolling resistance), powertrain characteristics (fuel conversion efficiency, gear ratios, gear train efficiency), and fuel consumption driving cycle. Model outputs include estimates for fuel consumption, acceleration, and a visitation map.

 

Physics of the Models

Fuel consumption is determined by the quantity of fuel used over a driving cycle. The driving cycle specifies the vehicle speed vs. time. An example of a driving cycle is the World Light Vehicles Test Procedure (WLTP) cycle shown in Figure 1.

 

Figure 1: Fuel Consumption Driving Cycle (WLTP Class 3b).

Figure 1: Fuel Consumption Driving Cycle (WLTP Class 3b).

 

Given the velocity history of Figure 1, the forces on the vehicle resisting forward motion may be calculated. These forces include inertia force, aerodynamic drag force, and rolling resistance. The total of these forces, called tractive force, must be provided by the vehicle propulsion system, see Figure 2.

 

Figure 2. Tractive Force Required.

Figure 2. Tractive Force Required.

 

Once vehicle speed and tractive force are known at each point of time during the driving cycle, the required torque and rotational speed may be determined for each of the drivetrain elements, as shown in Figure 3 for an Internal Combustion system, and Figure 4 for a Battery Electric Vehicle.

 

Figure 3. Internal Combustion Powertrain.

Figure 3. Internal Combustion Powertrain.

 

Figure 4. Battery Electric Vehicle Powertrain.

Figure 4. Battery Electric Vehicle Powertrain.

 

In this way, the required torque and speed of the engine or motor may be determined. Then using a map of efficiency, shown to the right in Figures 3 and 4, the energy demand is determined at each point in time. Summing the energy demand over time yields the fuel used over the driving cycle. The reader is referred to References 1 and 2 for a much more in depth description of the models.

Example Application

As an example application, consider the WorldAutoSteel FutureSteelVehicle (FSV).W-7   The FSV project, completed in 2011, investigated the weight reduction potential enabled with the use of AHSS, advanced manufacturing processes and computer optimization. The resulting material use in the body structure is shown in Figure 5.

 

Figure 5. FutureSteelVehicle steel grade application.

Figure 5. FutureSteelVehicle steel grade application.

 

This use of AHSS allowed a reduction in the vehicle curb mass from 1200 kg to 1000 kg. What are the effects of this mass reduction on fuel consumption and acceleration performance?  The inputs required for the powertrain model are shown in Table 1 for the base case.

 

Table 1: Model Inputs for Base Case

Table 1: Model Inputs for Base Case.

 

The results provided by the powertrain model are summarized in the acceleration-time vs. fuel consumption graph of Figure 6. Point A is the base case at 1200 kg curb mass. The lightweight case with same engine is shown as Point B. Note the fuel consumption reduction and also the acceleration time reduction. Often the acceleration time is set as a requirement. For the lighter vehicle, the engine size may be reduced to achieve the original acceleration time and an even greater reduction in fuel consumption as shown as Point C.

 

Figure 6. Summary of results of base vehicle and reduced mass vehicle.

Figure 6. Summary of results of base vehicle and reduced mass vehicle.

 

Using the parsimonious powertrain models allows such ‘what-if’ questions to be answered quickly, with minimal data input, and in a transparent way. The Parsimonious Powertrain Models are available as a free download at worldautosteel.org.