A357

A357 is a designation used for multiple, unrelated things, including an aluminum casting alloy and a United Kingdom road, and the two uses are not related beyond sharing the code.

Aluminum alloy A357 is an Al-Si-Mg casting alloy standardized for die casting and precision components. It typically contains about 7–9% silicon with small additions of magnesium and other trace elements to enable precipitation hardening. The silicon improves castability and fluidity, while magnesium provides potential for heat-treatable strengthening. A357 is selected for components that require complex shapes, good surface finish, and relatively high strength after heat treatment. It is commonly processed by die casting and then subjected to solution treatment and artificial aging (such as T6 temper) to develop strength. The alloy offers good corrosion resistance and dimensional stability, and it is machinable with conventional tooling, though silicon-rich alloys can require careful cutting parameters. Applications include automotive and industrial parts such as engine housings, pump housings, and other complex castings.

A-road in the United Kingdom: In the UK, A357 denotes a primary road in the national road network. As with other A-roads, it serves as part of the regional transport spine, connecting towns and linking with other major routes. The exact route, length, and termini vary along its course, but the designation indicates its role as a significant roadway within its region.