Development of a New High Strength Aluminum Casting Alloy for the Production of Suspension Components 2014-01-0999
The Counter Pressure Casting (CPC) process is particularly suited for the production of aluminum suspension components like wheel carriers or steering knuckles. Using a typical AlSi7Mg alloy such as A356 or EN AC-42100, yield strength above 260 MPa and elongation rates above 8% are possible in a high volume production. Although these are very good values for aluminum castings, the yield strength has to be improved to increase the light weight potential of such components.
The present work shows how this goal can be achieved by the development of a new aluminum casting alloy. Besides the modification of Si and Mg content, the addition of Cr leads to an additional dispersion hardening effect. In this way, yield strength above 310 MPa combined with an elongation of 7% can be assured in the CPC process after a T6 heat treatment. Fundamental microstructural investigations are shown as well as the results of tensile tests, high temperature strength, corrosion behavior and static and dynamic component testing. All presented results were achieved on existing components like steering knuckles and not on casted test bars.
To demonstrate the weight reduction potential of the presented alloy, the product development of a steering knuckle for a rear driven premium car was performed and prototypes were produced in the CPC process. All static and dynamic testings of the resulting components fulfilled the requirements and the series-production readiness was approved.