Materials and Corrosion. 2019;1–8. www.matcorr.com © 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim | 1 Received: 22 July 2019 | Accepted: 14 August 2019 DOI: 10.1002/maco.201911166 ARTICLE Numerical simulation of the aluminum–zinc–steel galvanic system for new designs of automotive chassis Allan Ruiz‐Garcia 1 | Rodrigo Mayen‐Mondragon 1 | Joan Genesca 1 | Esteban Morales‐Murillo 2 | Jaime Taha‐Tijerina 2,3 | Rodrigo Montoya 1 1 Facultad de Química, Departamento de Ingeniería Metalúrgica, Polo Universitario de Tecnología Avanzada, Universidad Nacional Autónoma de México, Apodaca, México 2 Tecnologías de Materiales avanzados, Metalsa S.A. de C.V., Apodaca, México 3 Engineering Department, Universidad de Monterrey, San Pedro Garza García, Nuevo León, México Correspondence Rodrigo Montoya, Facultad de Química, Polo Universitario de Tecnología Avanzada, Universidad Nacional Autónoma de México, Apodaca, 66629 Nuevo León, México. Email: rmontoyal@unam.mx Funding information Consejo Nacional de Ciencia y Tecnología, Grant/Award Number: 2018‐000012‐01 NACF‐11734; Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Grant/Award Number: TA100318 Abstract The requirement for lighter vehicles in the automotive industry promotes designs based on the combination of different metallic alloys. Such an approach, however, leads to galvanic‐corrosion risks, which compromise the durability of vehicles. One proposal to minimize such risks is to separate some of the chassis components by a Zn washer. The present work uses the finite element method to evaluate such an innovative design. The capacity of the washer to protect its aluminum alloy and carbon steel neighbors is assessed. As a worst‐case scenario, the bare metals are in contact with NaCl solution. Two electrolyte layer thicknesses are assumed: in the micrometer and in the millimeter range. Each case requires different mathematical models. For the thin film case, the zinc washer is able to protect its neighbors from corrosion. However, it sustains large corrosion rates, and thus its protection is effective only during short periods. Furthermore, as the Zn surface degrades and thus recesses, the “protective field” is blocked by the neighboring metal‐walls. The thicker the electrolyte layer, the weaker the Zn protective capability and, at some point, the corrosion of the aluminum alloy is unavoidable. KEYWORDS galvanic couples, modeling, thin electrolyte films 1 | INTRODUCTION Environmental laws regulating pollutant emissions as well as fuel consumption are becoming more strict nowadays. In accordance with this, the automotive industry has started a technological race to design lighter vehicles. The main challenge is, however, the identification of materials that could substitute the current steels being used for vehicles chassis. Different approaches in this direction have been taken. For example, the development of advanced high‐strength steels has allowed assembling thinner structural components without affecting mechanical performance. Another approach is the substitution of steel by lower density materials. However, mechanical requirements allow neither substitution of every structural component nor the use of all material classes. Plastics and ceramics are unfortunately not suitable candidates in most cases. Thus, the only practical possibilities remaining are to combine steel parts with lighter metal parts made of, for example, aluminum alloys (AAs). Such heterogeneous designs lead however to one of the main technological challenges regarding vehicles' durability: galvanic corrosion. The phenomenon originates when metals with different corrosion potential come in contact with