November_December_2021_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 1 2 1 to American Industrial Partners, a pri- vate equity firm. AMAG Austria Metall AG continues on its own independent path away from the merger turmoil, slowly growing its share of the European ABS market. In China, European carmakers needed aluminum ABS to support their growing local production, so both Kobe and Novelis opened new ABS heat treat and finish lines in 2017, supplied with cold rolled coils from Japan and Korea, respectively. Kobe started an expansion aimed at doubling its Moka Plant ca- pacity, all to support the growing ABS market in China. Kobe and Novelis later formed a joint venture in Ulsan, Korea, to feed their respective Chinese finish- ing lines, with Novelis breaking ground for a second line at its Changzhou plant in October 2018. All of this activity at- tests to the growth of the Chinese alu- minum ABS market. Domestic Chinese suppliers have not ignored the opportu- nity and have begun offering their first samples to prospective customers. Growth has taken place entire- ly using conventional direct chill cast- ing technology, as the long-anticipated switch to continuous casting has not materialized. The most serious exper- iment, Alcoa’s San Antonio Micromill, was a narrow production line built to demonstrate its new continuous casting and heat treating technology. Despite its width limitations, Alcoa and Ford successfully converted several produc- tion parts to the newmaterials, until the plant closure in late 2019. To date, there are no known plans to produce modern aluminum ABS using continuous cast- ing, although a few specialty producers such as Golden Aluminum in Colorado supply limited quantities of 5xxx sheet to some automotive customers. The separation between primary aluminum producers and rolling mills is now virtually complete, partly a re- sult of the relentless cost pressures on primary aluminum from China. The re- sponse of the Western primary suppli- ers has been to emphasize their green credentials and focus on their lower car- bon footprint. Several new technology projects have resulted in significant ad- vances, some driven by nontraditional customers. For example, Apple an- nounced in December 2019 that it had bought the first-ever carbon-free alu- minum from Elysis, an Alcoa-Rio Tinto joint venture. The emergence of credible 6xxx ABS sheet capability from China is bound to inflict similar cost pressures on the current Western suppliers, who find themselves operating in a world very much removed from the technol- ogy-driven aerospace sphere or recy- cling-dominated beverage can market. And unlike them, ABS is the subject of both cost and CO 2 footprint pressures. The rationale for using aluminum ABS began in pursuit of improved fuel con- sumption and performance. A maturing regulatory environment has replaced lower fuel consumption targets with reductions in CO 2 emissions. Classic life cycle analysis models based on in- ternal combustion engines show that aluminum-intensive solutions support- ed by direct stamping scrap recycling, such as Ford’s F-Series enterprise, have a net positive carbon footprint. The growth of aluminum ABS in closures and selected parts in mixed body solutions is a testa- ment to its effectiveness for lightweighting. But the in- creased acceptance of low- er-cost Chinese products and their higher CO 2 foot- print leave aluminum ABS vulnerable to doubts of its CO 2 reducing credentials, especially without prompt scrap recycling from the stamping plants (Fig. 1). As this article series shows, all of today’s alumi- num sheet-intensive prod- ucts use technology that flows directly from the de- velopments by Alcan and Ford in the early 1990s. But the progress of high volume, aluminum-intensive body- in-white (BIW) vehicles has stalled in a business that is by definition risk averse, ow- ing to the large investments required and small profit margins. New weight saving alternatives have become available as other technologies have matured, such as forged aluminum suspension com- ponents. Improved alloys and high-pressure die casting (HPDC) tech- nologies have yielded high perfor- mance thin-walled automotive body and chassis components. Tesla and other manufacturers have started to invest in HPDC capabilities as an alter- native to formed and joined sheet body structure. As of this writing, Tesla has purchased several of the largest pres- sure die casters in the world that it calls Giga Press to make very large structural components for its cars. The first one on the Model Y consolidated 70 parts into a single casting (Fig. 2). The press uses a non-heat treatable alloy specially de- veloped by Tesla to accept the prompt scrap from its collocated stamping op- eration, an elegant financial and oper- ational solution that also improves the CO 2 footprint. The future of sheet structures, al- ternative wrought products, and die castings will undoubtedly be written to- gether as the industry moves toward a Fig. 1 — 2018 world average and example power mix cradle-to-gate emissions intensity of primary aluminum (tons CO 2 emissions per ton of aluminum). Courtesy of world-aluminium.org . Fig. 2 — Diagram of Tesla Model Y with cast rear floor highlighted.