Contrary to popular belief, mass reduction does not automatically equal fuel savings, especially when it comes to urban driving. There are other factors that determine the fuel efficiency of a vehicle such as driving cycle, vehicle size and its powertrain. Until recently, there was a  lack of variety in engine types and powertrains, so even though automakers reduced the weight of car frames, they could not apply a complementary engine or powertrain to the lighter parts.

So, have automakers been lightweighting for nothing?

Of course not, in the past decade alone, engines and powertrains have also become extremely efficient through advancements in start-stop-systems and downsizing, and newer options including hybrids, electric batteries and range extenders that now allow automakers to capitalize on their lightweight materials.

Although there are several lightweight materials, below are 5 reasons why AHSS continues to be the lightweight material of choice for automakers:

1. Decision Makers Care About the Environment

Well, not everyone, but many countries around the world have started the process to phase out gasoline and diesel-fueled cars, including India and China, the two largest automotive markets in the world. Governments are taking serious action against climate change and it will reflect in their policies. Automakers are choosing to lightweight their vehicles for lower emission rates with AHSS, because not only is AHSS lightweight, there are no trade-offs with other vital features such as safety and cost-effectiveness.

2. Everyone’s Going Electric

Globally, automakers are investing in electric vehicles (EVs) in line with national and international environmental policies. However, EVs still have a ways to go before they become the norm. EVs will face the same safety requirements as regular cars, but with the added responsibility of protecting the battery and its flammable components during a crash.

In 2016 there were several car accidents involving the Tesla Model S, where leaked battery fluids caused fires. Automakers need to find a solution to make EVs as safe, and eventually, safer than traditional cars. As an innovative automotive material, AHSS was built for safety.

3. Safety is Always First

Safety is and should always be the number one priority for automakers, material providers and policymakers alike. Even with all the hype about autonomous driving and sensors, there is very little chance that policymakers will reverse the stringent safety regulations in place today. People want to feel safe, no matter what type of car they are getting into.  

2016 Smart Fortwo and the Mercedes S Class take part in a crash test (Source: Green Car Reports)

One possible material solution is Complex Phase (CP) steel, a type of POSCO GIGA STEEL for the vehicle’s side panels, bumper rails and door impact bars- the parts that determine the safety ratings of the vehicle. It has superior strength and shock-absorbing qualities, without the added weight of traditional high-strength materials, and that’s why carmakers such as GM Korea, Ssangyong Motors and Renault Samsung Motors all use POSCO GIGA STEEL.

4. Cost is Always Second

This goes for automakers as well as drivers on the consuming end. Drivers want lower costs without compromising safety and performance ratings, and desire fuel efficiency- a major reason why automakers are lightweighting.

Some automakers choose alternative materials such as aluminum and carbon fiber to meet lightweight requirements to find that not only are the materials more costly over steel, factories need an equipment overhaul to work with them. Moreover, there are additional costs related to training employees to work with new materials, whereas all auto manufacturers are familiar with welding and forming steel.  

Take a look at this infographic and see how AHSS stacks up against other lightweight materials in terms of cost and performance.  

5. It’s Not Over Till It’s Over

No two lightweight materials are the same when observed under the life-cycle approach, a comprehensive life cycle assessment of a material’s automotive carbon emissions from production to disposal. Often times, the process of manufacturing lightweight materials and improved powertrains result in more carbon emissions than they are saving.

The life cycle assessment can be used to determine the carbon output of a vehicle. (Source: World Auto Steel)

At the end of the day, steel has the lowest production-related emissions and can be recycled at the end of its lifecycle. Steel remains the most recycled material because it can be reapplied in different forms almost infinitely.

Automakers are increasingly incorporating lightweight materials to their new models. Although competition for the greatest market share of lightweight materials is fierce, AHSS is by far the leading material when it comes to lightweight solutions. According to McKinsey & Company’s Lightweight, Heavy Impact report, the percentage of high-strength materials used for cars will increase to 38 percent by 2030, compared to 15 percent in 2010. Steel continues to evolve according to the changing demands of the auto market, and for now, there is no other multi-solution material that can compete.

Cover photo courtesy of Hyundai.

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Auto Industry’s Challenge to Meet Consumer Demands

Mileage, design, and emissions. Which do you consider the most when purchasing a car? It is difficult to say that one is more important than the others, and fortunately, POSCO GIGA STEEL offers unique benefits for each one to meet the needs of today’s auto industry as it faces increasingly strict demands on safety and fuel efficiency.

More than ever, the industry is requiring that a vehicle goes longer distances with less fuel, which means the car must be lighter.  Also, technological advances have enabled cars with more power, requiring them to be safer. Consumers also want a car that represents their personality, demanding vehicles with more sophisticated and elegant designs.

Cars now need to drive smoothly, burn less fuel, and ensure safety, all while boasting an elegant design (Image courtesy of Mercedes-Benz AG).

While there are other conditions that need to be considered, it is paramount that cars meet the following three conditions in order to satisfy consumers: fuel efficiency, safety, and design. But these demands are becoming increasingly difficult to meet, and the only solution is to discover a technology that enables all of the above. For safety considerations, in the event of a collision, parts of the car also need to absorb the kinetic energy and protect the passengers inside.

In addition to having a battery and electric motor, the electric car is different from standard cars because the battery is a part of the frame itself.

6 Types of POSCO GIGA STEEL Tailored for Different Auto Parts

A car’s body frame requires different steel products for specific parts (Image courtesy of Renault)

POSCO GIGA STEEL is an advanced high-strength steel (AHSS) that can meet these various demands. Let’s take a look at the different types of POSCO GIGA STEEL products and how each one is being used in different parts of the car.

Complex Phase (CP) Steel

Complex Phase (CP) steel is often used to make reinforced auto parts that require high crashworthiness ratings, such as sill side panels, bumper rails, and door impact bars. It plays an extremely important role in the car frame as it is highly resistant to dents or bumps. In the past, the side panels of race cars were purposely made to be thicker in order to prevent dents and protect the driver inside and this naturally led to the vehicle becoming considerably heavier. However, CP steel minimizes these disadvantages. In the event of an impact, cars made with CP steel retain its original shape considerably better than other car frames due to its high strength and also has an exceptional ability to absorb all of the energy while still exhibiting an impressive thinness. It is often incorporated into the sill side panels and door impact bars to allow for a more spacious design.

Dual Phase (DP) Steel

Dual Phase (DP) steel can be easily welded and deformed and boasts a high level of total elongation (the rate at which the material is stretched without snapping). DP steel is commonly used in seat rails or other lower body reinforcements that run underneath the passenger seat. The tensile strength is at least 980MPa, but because it also exhibits impressive ductility, it can easily be used for random spare parts.

Transformation Induced Plasticity (TRIP) Steel

Transformation Induced Plasticity (TRIP) steel first made its way into the auto industry about six years ago. As the auto industry is beginning to value lightweight cars more and more, TRIP steel has received more attention. It is mainly used in the inner parts of the car body. This part of the car needs to absorb shock and impact and also be flexible enough to be fitted around the complex inner structure of the car. With TRIP steel’s outstanding combination of strength and ductility, it is one of the most commonly used high-strength automotive steels in the auto industry today.

Martensite Steel (MART)

Because Martensite steel is naturally high in strength, thinner sheets produced from roll forming (a metal forming process in which steel is continuously shaped or formed until it reaches a desired cross-section) still retain the same level of performance as conventional parts. Thinner parts also have the added benefit of reducing the weight.

Hot Press Forming (HPF) Steel

Hot Press Forming (HPF) steel is a different class of steel made with a unique steel production process. Typically, as steel becomes higher in strength, it is more difficult to mold into the desired shape through conventional processes. However, through the HPF process, the steel is heated to 950℃ before press forming. At high deformation temperatures, steel sheets are very soft so that difficult shapes can be obtained easily. During forming, the heated steel sheet cools down rapidly in the die block, so that the resulting pressed parts have a very high strength level. Due to its combination of high strength and formability, HPF steel is often used in the B-pillar of a car which requires intricately shaped parts as well as the A-pillar roof side rails which are prone to damage.

Post Heat Treatment (PHT) Steel

The chassis that supports the car frame needs to be extremely durable and resistant to impacts or shocks on the road as its main function is to improve the ride quality of the vehicle.
In order to increase the durability and torsional resistance, the material needs to be quenched and tempered. Before going through the heat treatment portion of the process (quenching), the material can be easily molded into spare parts due to its reduced strength. After being molded, it is heated up to 950°C and then rapidly cooled by water. This is why PHT is called “post-heat treatment steel”. Due to its ultra-high strength, it also has lightweighting benefits and is typically used in a vehicle’s chassis, stabilizer bars in a suspension system, and torsion beams.

These six types of POSCO GIGA STEEL each have their unique advantages in terms of processability & strength, production cost, and ease of application. Compared to conventional materials, thinner pieces can be used while still retaining the same level of performance and strength. Due to these incredible characteristics, POSCO GIGA STEEL is able to meet the increasingly stringent requirements of the auto industry for safety and efficiency.  

Image courtesy of Renault

Researchers in the auto industry are constantly looking for a stronger, more formable material. As the auto industry undergoes another paradigm shift, POSCO GIGA STEEL will continue to offer unique solutions that can satisfy both automakers and consumers.

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