The automotive industry is always seeking innovation, striving for lighter, stronger, and safer vehicles that meet both sustainability targets and consumer expectations. Materials with a high strength-to-weight ratio are at the heart of this evolution, and steel S690 is increasingly being adopted thanks to its superior mechanical performance compared to conventional steels.
Steel S690 is a high-strength low-alloy steel (HSLA) that belongs to the family of quenched and tempered steels. It is engineered to deliver excellent structural strength, toughness, and weldability, making it suitable for demanding industries such as automotive, construction, and heavy machinery.
S690 Properties
The exceptional S690 properties come from its specialized heat treatment process (quenching and tempering), which optimizes both strength and toughness. Key properties include:
- Yield strength: typically 690 MPa, up to 960 MPa depending on the grade
- Tensile strength: between 770 and 940 MPa, ensuring excellent load-bearing capacity
- Good weldability: achievable with advanced techniques and controlled parameters
- Improved toughness: even under dynamic loads and challenging environments
- Reduced weight: allows lighter structures without compromising safety or performance
These features make steel S690 one of the most reliable options when balancing performance, safety, and lightweight design.
The automotive industry is always looking for the next step ahead. Continuously seeking for new innovations and looking for materials meeting high safety standards and consumer demands. Steel has a central role in this. The use of steel S690 has gained in popularity thanks to its mechanical properties.
Steel S690 belongs to the family of high-strength low-alloy steels (HSLA) characterized by its excellent strength-to-weight ratio, toughness and weldability. In order to achieve its superior properties, the material is processed through heat treatment (quench and temper – QT).
The differences between carbon steel S355 and S690 are many:
| S355 Steel | S690 Steel |
| Yield strength: S355 has a Yield strength of 355 MPa | S690 has a yield strength ranging from 690 to 960 MPa, making it significantly stronger than conventional mild steels. |
| Tensile strength: its value for S355 ranges from 470 to 630 MPa | S690’s range is between 770 and 940MPa. This superior value allows for lighter structures and increased load-bearing capacities. |
| Impact Toughness: due its lower strength S355 can absorb more impact energy before fracturing | S690 has a slightly lower impact level. However, its high-strength-to-weight ration still makes it advantageous in structural designs. |
| Cost and availability: Being widely used, S355 is generally more available and less expensive | S690 requires less maintenance over time decreasing the cost in its life cycle |
What are the benefits of using steel S690 in racing and sports car sector?
- Lightweight design: steel S690’s high strength allows the design of lighter components without compromising their structural integrity. Additionally, this also helps to achieve reduced emissions, thus addressing sustainability concerns
- Enhanced crashworthiness: besides the high strength, S690 also presents superior energy absorption capabilities, making it an ideal material for safety components. The purpose of these components is to effectively dissipate crash forces and to protect the drivers and occupants in case of impact.
- Cost efficiency: despite its higher material costs compared to traditional mild steels, the use of S690 can lead to cots savings in the long run. First, its lighter weight reduces fuel consumption of the entire vehicle’s lifespan, while its improved durability reduces maintenance and repair expenses.
Where specifically is used S690 in this industry?
- Body-in-white components (BIW), i.e. basically the car body’s sheet. This helps to increase crash performance while reducing weight.
- Safety systems like side impact bars or bumper reinforcements, door reinforcements and front-end structures, that can benefit from the energy absorption characteristics of S690, thus enhancing the vehicles’ safety standards.
- Suspension and chassis parts, where lightweight designs again plays a crucial role in improving the vehicle’s handling and dynamics.
What are the challenges of using S690?
First, manufacturing complexity, processing and forming this material require specialized equipment and expertise. After undergoing manufacturing processes, proper heat treatments are essential to avoid material degradation and the loss of its mechanical properties. Even welding this material is not easy. This steel requires a very precise control of heat input and welding parameters to prevent the formation of large heat-affected zones and to maintain its mechanical properties. This is why traditional welding may be too critical, while advance welding techniques such as laser welding can help obtain optimal results. Finally, the high material costs compared to mild steels may pose a barrier to its widespread adoption, particularly in cost-sensitive market segments.
Driving Innovation with Steel S690
Steel S690 has many potentials for enhancing the automotive design, performance and safety with its exceptional mechanical properties, however It is a challenging material to work with and only specialized manufacturers as Montanstahl can process it properly.
Please feel free to contact us to learn more about this material and how it can be used in your next project!