Inside JLR and ArcelorMittal's off-cycle study to rethink steel vs aluminium
An open-brief engineering exercise shows how advanced steels, coatings and multi-part integration can rival aluminium on cost, mass and carbon – without compromising crash and battery safety
When Jaguar Land Rover set out to challenge its long-standing reliance on aluminium-intensive body structures, the exercise was never intended as a simple materials swap. Instead, JLR approached the study as an open engineering challenge: keep vehicle attributes intact, look for commercial sense in cost and weight, and use the opportunity of an off-cycle programme to generate fresh ideas unconstrained by the pressures of an active launch.
The team was not given a hard mass or cost target; instead, the key constraint was that attribute delivery should not be degraded...When it comes to cost and weight, we're looking for good business sense on opportunities
Discussing this project and the collaboration with Olena Hudimova, Global Technical Coordinator at ArcelorMittal, and James Morrad, Senior Manager for HV Battery Enclosures and Subframes at JLR, Morrad explained that the resulting work was an exercise in co‑engineering and pragmatism, marrying JLR’s requirements with advanced steels, coatings and manufacturing thinking to produce options that made sense at a full‑vehicle level.
Materials change: no compromise on attribute delivery
JLR’s remit for the study was deliberately broad rather than prescriptive. Morrad said, “The team was not given a hard mass or cost target; instead, the key constraint was that attribute delivery should not be degraded,” adding that “When it comes to cost and weight, we're looking for good business sense on opportunities.” That stance reflected JLR’s dual heritage: a premium brand where aluminium has been a signature of its architectures, and a recognition that steel remains competitive in areas where cost or manufacturability call for it. The project focused on a mature, pre‑launch platform so the team could leverage existing correlations between virtual models and physical test data, enabling more confident iteration in simulation before committing to physical validation.
ArcelorMittal was selected as a partner because it brought raw‑material expertise and an engineering-first mentality to the table. Morrad explained that raw‑material suppliers can be less influenced by particular downstream technology solutions and therefore help keep the conversation focussed on material selection and vehicle‑level optimisation. For ArcelorMittal, the programme moved quickly from commercial negotiation to technical collaboration. As Hudimova, Global Technical Coordinator for ArcelorMittal Europe, recalled, “Within a few weeks after the initial discussions, Body Director at JLR, Dr. David Weir, came to our global R&D centre to assess our capabilities, meet our specialists, and to understand if we could deliver this ambitious study.” That visit established a working rhythm and a level of trust that allowed both organisations to share detailed bill‑of‑materials (BOM) and CAE data, enabling a genuine co‑engineering approach.
The most pressing and non‑negotiable requirements for JLR were centred on safety and battery integrity. Crash performance, battery sealing and battery thermal safety were repeatedly flagged as critical. “We'll always end up talking about crash being a challenge… vehicle safety, sealing batteries, the car, and then battery thermal safety,” Morrad said, pointing to the battery lid and the battery seal as components that make outsize contributions to those performance areas. Given those demands, any material or design change had to preserve or improve the baseline attributes while also offering a credible route to cost reduction or manufacturing simplification.
ArcelorMittal’s technical proposition combined advanced high‑strength steels, specialised coatings and multi‑part integration concepts. Hudimova emphasised that their value proposition went beyond simply offering a commodity steel grade “We bring extensive engineering experience, material knowledge, processing know-how, and technical support that can create significant value at the vehicle level.” In crash‑critical regions, martensitic steels were a central part of the conversation. “For anti‑intrusion application, we offer martensitic steel solution with extremely high strength and excellent formability. It enables lightweight design while enhancing passenger safety,” Hudimova said, stressing that the combination of strength and ductility made these grades particularly suited to intrusion protection while still being manufacturable.
By sharing their BOM and CAE data, JLR enabled our team to analyse the vehicle architecture and to identify opportunities to optimise cost, weight, manufacturing complexity, and CO2 performance
Another strand of ArcelorMittal’s offer covered corrosion and thermal performance in the battery environment. The supplier applied advanced zinc‑magnesium coatings for corrosion‑critical parts, recognising that mixed‑material joints and battery enclosures demand durable surface protection. Hudimova pointed to specific coating solutions that provided age protection and corrosion resistance, an important reassurance for battery‑adjacent components where longevity and safety are combined requirements.
Cost reduction through multi-part integration approach
From a manufacturing and cost perspective, ArcelorMittal pushed the benefits of multi‑part integration. By consolidating several components into larger stampings, the number of welds and joining operations can be reduced, simplifying the body shop footprint and lowering assembly complexity. That potential to offset raw‑material price differentials through manufacturing simplification became a central theme of the business case discussions. Hudimova noted that such consolidation can “translate into the bodyshop footprint, tooling, assembly line, manufacturing complexity,” and that the total business case often looks more favourable when these manufacturing impacts are captured rather than focusing solely on per‑kilogram material prices.
The assessment and validation approach was pragmatic and iterative. JLR and ArcelorMittal shared CAE data and BOMs, allowing the supplier’s R&D team to propose areas where advanced steel grades and modified architectures could yield meaningful vehicle‑level benefits. “By sharing their BOM and CAE data, JLR enabled our team to analyse the vehicle architecture and to identify opportunities to optimise cost, weight, manufacturing complexity, and CO2 performance,” Hudimova said. Most of the study remained in the virtual domain, using ArcelorMittal’s material data cards to accelerate early analysis. Morrad acknowledged this compromise “We've used material data cards from Arcelor rather than redo our own for the sake of this project… in normal course, we would move on to recharacterise them ourselves.” The approach allowed the teams to iterate quickly while reserving physical testing for the most promising candidates.
Targeted physical validation was used where virtual methods were insufficient to fully de‑risk an idea. Morrad noted that subsystem testing, notably for the battery lid, progressed beyond simulation and produced positive outcomes, giving the programme tangible validation points and a pathway for later deployment into production programmes. The partnership’s ability to move between virtual and physical validation, backed by the maturity of the chosen architecture, created confidence in the results without forcing a mass‑neutral outcome at all costs. “We were not held exclusively to mass neutral,” Morrad added. “We're looking for good business case decisions.”
Several substitution opportunities stood out in the study. Battery enclosure components and lids were obvious targets because of their influence on crash containment and thermal safety, and because their design evolution can unlock consolidation benefits. Door rings and multi‑part consolidation delivered one of the more significant wins in the programme; Morrad pointed to the door ring study as a clear example of where a steel solution and revised architecture could outperform a simple materials substitution. Anti‑intrusion sills were another area where martensitic grades provided a way to preserve or enhance crash performance while enabling simpler assemblies.
In programme development and in launch of activities, you inevitably drive decisions based on delivery timing and not necessarily cost and weight optimisation. So, it's nice to do a retrospective review with a fresh eyes engineering group
Factoring in sustainability
Sustainability formed a parallel lens to cost and mass in the evaluation. JLR has explicit ambitions on its journey to net zero, and both partners treated low‑carbon credentials as an integral part of the business case. Morrad framed the discussion succinctly “We always try and focus on the right material in the right place… lower carbon, high strength steels can offer competitive alternatives to aluminium basically.” ArcelorMittal underlined that greener steels need not imply manufacturing compromises; Hudimova described successful stamping trials using X‑Carb lower‑carbon steels for Range Rover door beams and tunnel toppers and reported that their partner Gestamp had “confirmed that there is no difference between stamping performance of conventional and green steel.” For ArcelorMittal, the broader trend is to treat cost, mass and carbon as co‑optimisable objectives rather than isolated constraints noted Hudimova.
Perhaps the most striking outcome of the collaboration was not a single definitive design, but the demonstration of how open data sharing and genuine co‑engineering can produce richer, more deployable options than either partner could have developed alone. Hudimova described the programme as “the best example of genuine OEM‑supplier synergy,” while Morrad emphasised the value of doing the work off‑cycle so that the team could surface ideas for later implementation without being forced into delivery timelines that bias decisions to speed rather than optimisation. “In programme development and in launch of activities, you inevitably drive decisions based on delivery timing and not necessarily cost and weight optimisation. So, it's nice to do a retrospective review with a fresh eyes engineering group,” he said.
The study does not herald an immediate, wholesale switch from aluminium to steel at JLR. Instead, it provides a framework for how advanced steels, smart coatings and architectural consolidation can be applied in the right places to deliver competitive outcomes across performance, cost and sustainability metrics. With subsystem validation already producing positive results in areas like the battery lid and door ring, and with stamping trials showing no penalty for greener steel, the collaboration lays out solid options for future programmes.
FIND OUT MORE ABOUT ARCELORMITTAL'S HIGH-STRENGTH STEELS AND VEHICLE STRUCTURE SOLUTIONS HERE
