Standards for steel grades according to BMW standards GS 93032
Bayerische Motoren Werke (BMW) has defined specific requirements for steels used in its vehicles. These requirements have been standardized in the company’s own GS 93032 standard. It ensures that the materials used meet the highest quality standards and are optimally adapted to the production processes and functional requirements in automotive engineering.
BMW divides its steel specifications into different categories, each covering different applications and requirements. The following sections provide a detailed overview of the individual standards and the associated steel grades.
GS 93032-2: Deep drawing steels
The deep-drawing steels in accordance with GS 93032-2 are specially developed for use in car body construction. They offer excellent formability, which makes them ideal for the production of components with complex geometries. These include cold-rolled grades such as CR2, CR3 and CR4 as well as hot-rolled grades such as HR2.
These steels offer an impressive combination of economy and quality and are suitable for various forming processes on a large industrial scale.
GS 93032-3: Microalloyed steels
Microalloyed steels combine high strength with good formability. The GS 93032-3 standard specifies these steel grades, which are available both cold-rolled and hot-rolled. Cold-rolled: Grades such as CR210LA to CR460LA offer a wide range of strength properties, making them particularly suitable for components with high strength and weight-saving requirements. Hot-rolled: The hot-rolled variants (e.g. HR300LA to HR500LA) are cost-effective solutions for large-area structural components.
This category also includes hot-rolled fine-grain steels such as HR300MC to HR500MC, which offer additional advantages in terms of strength and machinability thanks to their precisely controlled microstructure.
| Cold rolled | Hot rolled | Hot-rolled fine-grained steels |
|---|---|---|
| CR210LA | ||
| CR240LA | ||
| CR270LA | ||
| CR300LA | HR300LA | HR300MC |
| CR340LA | HR340LA | HR340MC |
| CR380LA | HR380LA | HR380MC |
| CR420LA | HR420LA | HR420MC |
| CR460LA | HR460LA | HR460MC |
| HR500LA | HR500MC |
GS 93032-4: Bake-hardening steels
Bake-hardening steels (BH) offer increased yield strength after heat treatment. This makes them ideal for body parts where high final strength is required in addition to good formability. The standard includes variants such as CR180BH to CR270BH, which are mainly used for outer skin components.
GS 93032-5: IF steels
Interstitial-free steels (IF) are characterized by outstanding deep-drawing properties. This property is achieved by an extremely low content of interstitial elements such as carbon and nitrogen. Steel grades such as CR180IF and CR210IF meet the requirements for maximum formability.
GS 93032-7: Dual-phase steels (DP)
Dual-phase steels combine high strength and elongation, which makes them ideal for safety components and structural applications. The range extends from CR250Y440T-DP to CR700Y980T-DP. These steels are available both cold and hot rolled and are valued for their superior crash absorption properties.
GS 93032-8: Complex phase steel (CP)
Complex-phase steels (CP) offer an outstanding combination of strength and formability. They are suitable for components with high energy absorption, such as reinforcements or sills. The standard includes CR570Y780T-CP and HR660Y760T-CP for various production requirements.
GS 93032-9 – TRIP steel
Transformation Induced Plasticity (TRIP) steels are characterized by an exceptional combination of high ductility and strength. They are often used in areas where high energy absorption is required, such as CR400Y690T-TR.
GS 93032-10: Martensitic steels (MS)
The martensitic steels achieve maximum strength thanks to their specific microstructure. Examples include CR950Y1200T-MS and HR900Y1180T-MS, which are used for heavy-duty components such as side impact protection and B-pillars.
Cold-rolled dual-phase steels according to GS 93032-11
Dual-phase steels (DP) combine high tensile strength with excellent formability and are particularly suitable for safety-relevant components that have to withstand high loads. They are based on a microstructure of martensitic islands embedded in a ferritic matrix, which achieves optimum properties for deformation and energy absorption.
Uncoated cold-rolled dual-phase steels
The uncoated steels such as HC260X, HC300X and HC450X offer flexibility for applications where no special corrosion resistance is required. They are often used in structural internal parts that are not directly exposed to the environment.
Electrolytically galvanized cold-rolled dual-phase steels
The variants with zinc coating (HC260X+ZE to HC540X+ZE) offer improved corrosion resistance combined with high formability. The electrolytic coating provides a precisely controlled protective layer that is suitable for applications in the outer body.
Hot-dip galvanized cold-rolled dual-phase steels
Hot-dip galvanized steels(HC260XD+Z to HC540XD+Z) are ideal for body parts that are exposed to extreme weather and environmental influences. The zinc coating effectively protects against corrosion and at the same time offers good welding properties.
Galvannealed cold-rolled dual-phase steels
The galvannealed variants (HC260XD+ZF to HC380XD+ZF) are characterized by their improved weldability and painted surface adhesion. These properties make them ideal for use in outer skin and visible body parts.
Hot-rolled complex-phase steels according to GS 93005-14
Complex-phase steels (CP) combine high strength with good ductility, which is achieved through their complex microstructural composition. They consist of several metallurgical phases, such as ferrite, bainite and martensite, which guarantee both strength and crash resistance.
Uncoated CP steels
HD680C offers high strength for structural components where increased corrosion resistance is not required. Typical applications include beams and reinforcement components in vehicles.
Electrolytically galvanized CP steels
HD680C+ZE is used for components that require controlled corrosion resistance, especially in areas with limited exposure to moisture and salt.
Hot-dip galvanized CP steels
HD680CD+Z offers maximum corrosion protection for structurally relevant applications in exposed environments, such as load-bearing parts in the underbody area or exterior structural components.
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Alex Bachmann
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Alex.Bachmann@ESB-Group.com