CR420LA - Cold-Rolled Micro-Alloyed Steel according to VDA 239-100

Quality	Standard	Possible coatings
CR420LA	VDA 239-100	UC, EG, GI, GA, AS, ZM

Quality

Testing direction	Yield Point R_e (MPa)	Tensil Strength R_m (MPa)	Elongation type 1 _A50 (in %)	Type 2 A₈₀ (in %)	Type 3 A₅₀ (in %)
L	420 – 520	480 – 600	≥ 18	≥ 17	≥ 18

Mechanical Properties

C %	Si %	Mn %	P %	S %	Al %	Ti %	Nb %	Cu %
≤ 0,12	≤ 0,50	≤ 1,65	≤ 0,030	≤ 0,025	≥ 0,015	≤ 0,15	≤ 0,09	≤ 0,20

Chemical properties

With CR420LA grade, you enter the realm of high-strength, cold-rolled thin sheets, designed for the most demanding applications in modern automotive manufacturing. Within the VDA 239-100 standard, CR420LA represents a significant leap in strength compared to lower grades, while still maintaining residual formability. This specific combination of properties makes the material a crucial element in the passive safety structure of vehicles. The development and standardization of this grade are a direct result of the steadily increasing demands for energy absorption during collisions. CR420LA is therefore not a general-purpose steel, but rather a highly specialized material whose application is explicitly limited to the automotive industry, where its mechanical performance characteristics are maximized.

Properties

Its mechanical properties are impressive, reflecting its role as a high-performance steel. The minimum yield strength (Rp0.2) is 420 MPa, and the minimum tensile strength (Rm) is 480 MPa. These values clearly demonstrate the material’s load-bearing capacity. As a direct effect of its increased strength, the elongation at break is reduced compared to lower grades like CR340LA or CR380LA, but still remains at a minimum of 17%. This ductility reserve is crucial because it allows for a certain degree of cold forming, even though the part geometry needs to be designed more carefully. The chemical composition is similar to other LA grades with a very low carbon content, typically below 0.12%. The high strength is achieved through optimized micro-alloying with elements like niobium and titanium, which strengthen the microstructure through precipitation hardening and grain refinement. This ensures excellent weldability, which is of utmost importance for the automated series production of body components. Formability in the deep-drawing process is good, but it requires precise tool design to prevent cracking.

Applications

CR420LA is typically used where high static and dynamic forces occur and significant energy absorption is required in the event of a crash. The main areas of application are:

Bumper beams and reinforcements: Here, the material must deform in a controlled manner during a collision to absorb energy and protect the vehicle structure.

Side impact beams in doors: These beams are designed to absorb impact energy during a side collision and protect the passenger cell from intrusions.

Reinforcements in A and B-pillars: These components must exhibit high rigidity to support the roof structure in the event of a rollover.

Crossmembers and reinforcements in the floor structure: The high strength here allows for a reduction in material cross-section, which lowers vehicle weight while simultaneously improving crash performance.

The use of CR420LA is a clear sign of a targeted material selection, where safety is the top priority.

Conclusion

CR420LA according to VDA 239-100 represents a milestone in the development of cold-rolled steels for automotive manufacturing. Its combination of high strength and sufficient formability makes it an ideal material for safety-critical structural parts that must function reliably under extreme loads. For engineers and technicians working on the development of next-generation car bodies, CR420LA offers the opportunity to reconcile the goals of lightweight construction and passive safety. It’s a material that pushes the technological boundaries of cold forming to enable more robust, lighter, and efficient vehicles.