Automotive Engineering - September 2024 - 24

MATERIALS FEATURE
BLAZER EV
IS A
STEELINTENSIVE
SHOWCASE
GM
elevates the ferrous
state-of-art with new
body and battery
structures.
by Lindsay Brooke
Blazer EV white body showcases innovative materials solutions to balance
mass, structural performance, cost and occupant safety.
C
hevrolet Blazer EV customers are likely to cite the Ultium battery
and dual-motor driveline as their vehicle's most advanced
technologies. But in doing so, they'd miss an equally key aspect
of GM's sporty midsize electric SUV: its steel-intensive
body structure featuring a broad mix of alloys and an impact-defying
battery enclosure.
The words 'steel' and 'BEV' seem incongruent, given the widely
forecasted trend toward aluminum architectures based on two or
three large castings. GM itself has invested heavily in the Teslapioneered
'gigacasting' tech and will deploy it first in Cadillac's new,
ultra-exclusive (and much-delayed) Celestiq flagship. But GM's electrification
strategy depends on a variety of material and body-structure
solutions. It's a horses-for-courses approach aimed at balancing
performance and product affordability, explained Blazer EV's chief
engineer Hoda Eiliat.
" In GM's materials position, steel is obviously the most cost-effective
approach, " Eiliat declared in her keynote at the 2024 Great
Designs in Steel conference. Innovations in new alloys, metal forming
and joining technologies continue to drive steel's competitiveness,
she told SAE Media following her presentation, adding that " obviously,
we have to look elsewhere when we have mass and parts-consolidation
priorities. "
The breakdown of Blazer EV's body materials shows increased
adoption of tougher, more mass-efficient steels. Forty-five percent of
the 5,337-lb (2,421 kg) all-wheel drive vehicle's total materials composition
is in medium-high-strength alloys boasting a yield strength
of 180-580 MPa. Thirty percent of the total is split evenly between
24 September 2024
mild steel (mainly body outers) and ultra-highstrength
alloys, the latter including multi-phase,
Martinsitic and Gen-3 products rated at 980 MPa or
above. Dual-phase advanced high-strength steels
(590-780 MPa) constitute 9% of the total.
The most prominent use of aluminum is in the extruded
side rockers in 6082 alloy with a T6 heat treatment.
Managing mass and impact load
Beyond steel's cost superiority, GM considers the ferrous
metal to be vital for optimizing product diversity,
rapid refreshes, and achieving production scale. All are
essential for democratizing EVs, Eiliat said. The Blazer
EV is one of eight vehicle programs that are currently
on GM's so-called BEV Crossover platform, with more
in development. The basic architecture accommodates
two major variants serving Buick, Cadillac, Chevy,
Honda and Acura nameplates. They're differentiated
by long and short distances measured from the driver's
ball-of-foot to the front axle centerline. Blazer's
all-new steel upper body structure also has two variants:
base roof and sunroof. Much of the lower structure
carries over parts from the Cadillac Lyriq.
Blazer's underbody structure is engineered to accommodate
front- or all-wheel drive and two different
battery enclosures, depending on whether the vehicle
AUTOMOTIVE ENGINEERING
LINDSAY BROOKE
Automotive Engineering - September 2024

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