Abstract Scope |
The use of dissimilar materials to the body-in-white design in the automotive industry has dramatically increased in the last decade due to its impact on weight and energy economy. By applying a low-density aluminum alloy and higher strength steel, automakers can reduce energy consumption for both fossil fuel- and battery-powered vehicles. However, joining these materials using conventional technologies has been challenging due to the formation of brittle intermetallic phases at the steel-aluminum interface. The use of interlayers to facilitate the joining of metallurgically incompatible materials has been used for decades. In most applications, the interlayer prevents and minimizes the intimate contact between the two materials, thus avoiding low-temperature melting or the formation of undesirable phases. However, in some cases, interlayers react with one or two of the materials joined, contributing to the welding itself, as in the case of transient liquid-phase joining or as in the case here presented.
There is limited knowledge concerning interlayer composition's role on intermetallic phase formation and resultant mechanical performance when reactive interlayers are used. This work addresses the use of Cr-containing alloys as intermediate interlayers to improve the joinability of Al-alloys to Advanced High-Strength Steels. The findings have shown that interlayer alloys with specific Cr content effectively mitigate the intermetallic phases layer formation and improve mechanical performance. Fundamental metallurgy, including thermodynamic and kinetic studies, has clarified Cr's effect, paving the path for the science-based development of cost-efficient interlayer technology for aluminum to steel joining within the transportation industry. |