Hydro introduces S-grade™ aluminum alloys for safety critical components

An aluminum alloy designed for side impact crush loads that can help OEMs further reduce the weight and carbon footprint of their vehicles has been made available to the market by Hydro.

Hydro’s S-grade™ fills the gap left by the widely used C-grades, which are designed to undergo axial crush loads on short, not very complex, light and easy to quench parts such as engine carriers and crush boxes, but not for complex, heavy and long length parts with tight assembly tolerances that require damage tolerance in side impact crush such as side sills and side members.

C-grades, with their high quench sensitivity, also require post-extrusion processing to meet stringent shape control on large, complex, and long extrusions, which S-grades can avoid, owing to a reduced quench sensitivity while retaining their high crash performance.

Hydro says the S-grade™ portfolio has been built to offer higher design flexibility, especially shape tolerances, as well as increased strength levels, damage tolerance, durability and joinability, from S24

(minimum yield strength 240 MPa) to S37. OEMs would find the greatest benefits with S24 and S28 on sill type products, while the higher-strength S32, S34 and S37 alloys are better suited for bumper beams and side impact beams.

The S-grade™ portfolio is also achievable with high recycled content – over 75% end of life scrap. Its design also allows for increased recyclability through the exclusion of peritectic elements such as vanadium, which is frequently used in high-strength C-grades.

S-grades™ were designed to meet the highest OEM requirements at component level rather than just at material level, mainly to account for adjustments to profile design and any resulting process adjustments, as well as part-specific damage tolerance requirements in crash. All this without compromising on design flexibility and process ability.

S-grades™ are compatible with existing industry standards facilitating their introduction and usage by automotive engineers whether at Tier 1s or OEMs, to build better and safer vehicles, according to Hydro.

Automotive Industries (AI) asked Alexis Skubich, Innovation & Technology Director – Extrusion Europe at Norsk Hydro, how the company’s collaborative approach to research and development is expanding the use of aluminum in vehicles.

Skubich: It is essential for all our partners to continuously challenge our knowledge. Our academic partners provide fresh ideas, the OEM partners set continuously moving targets, and our internal partners ensure the Hydro Group delivers consistent value proposals.

AI: How has alloy development contributed to making aluminum a key material choice for structural parts requiring low weight, high strength, and crash performance?

Skubich: Exploring alloy designs beyond basic EN/AA standards has allowed to make aluminum alloys and especially 6xxx alloys and extrusions solutions of choice for automotive body structures.

AI: What separates S-Grade from other alloys in the market?

Skubich: It delivers high performance on key functions for side impact crush parts, such as lightweight, damage tolerance (high energy absorption), ease of assembly (precision extrusion), ease of recycling and compatibility with low CO₂/ high recycled content supply chains.

AI: Is it suitable for complex profiles and components?

Skubich: It allows the extrusion of complex profiles with excellent damage tolerance in side impact crash with precision tolerances that allow efficient component production from the resulting ease of assembly.

It is also important to note that lightweighting is also achieved by reduced variability in tolerances that allows nominal values such as thicknesses to be offset.

AI: What are the most suitable applications for the S-Grade?

Skubich: Side sills, side sill inserts, door guard beams, battery side members in the case of structural enclosures. Bumper reinforcements can also benefit from their damage tolerance under pole impact.

AI: How does S-Grade contribute to decarbonization and circularity ambitions of OEMs?

Skubich: The most efficient means of decarbonizing is to reduce material usage. S-grade precision extrusions, due to their high damage tolerance, significant reductions in weight, which translate into CO₂ and cost savings.

AI: Do you collaborate with OEMs in order to identify opportunities for S-Grade and further develop alloys and materials based on individual needs?

Skubich: We continuously collaborate with OEMs because increasing performance, reducing weight and CO₂ and cutting costs are never-ending endeavors.

One of the focus areas is the provision of crash protection for electric vehicle batteries. OEMs use either a battery side member for protection or a side sill, but not both.

Utilizing our range of high-strength and energy-absorbent alloys, we can produce complex extruded components for automotive

sill assemblies. Benefiting from aluminum’s light weight, as well as the strength of the metal, sill assemblies can provide side impact protection while improving running efficiency.

In the case of the battery side member, the battery casing is primarily an enclosure that requires leak-proofness, ease of assembly, NVH but little crash resistance. Hydro has developed a cost-efficient remote laser welded concept enabled by proprietary alloy Al-lean to meet this demand.

AI: What is next for Hydro Extrusions?

Skubich: To continue growing our portfolio of low CO₂, high performance solutions for our customers and reduce barriers to introducing them. We will also continue to push for more game-changing developments, whether they be alloys or processes, with a keen focus on sustainability and automation within our specialist manufacturing solutions. We will continue to build our relationships with OEMs, including being positioned as an integral part of the supply chain.