Mechanical Properties Gradient Existing in Real Castings Taken Into Account During Design of Cast Components

摘要

The problem concerns the structure and properties heterogeneity of cast products, on the example of the Al-Si (A356) alloy. The trends of usage of this knowledge by constructors of that kind of products are described in this paper. It is well known that soundness of cast products is a postulate formulated by designers and users of machines and devices, where castings are among important parts. It is often forgotten though, that perfect soundness (density) of the cast material in ready for use parts simply does not exist. The gas and shrinkage porosities, present in semi-finished casting products, obtained from a liquid state of an alloy is the result of phenomena occurring during multiphase metallic system crystallization. Still, general introduction of the tolerance of damage rule requires knowledge about casting technology, inspection of the state of discontinuity of casting structure. The use of coupled experimental researches (including NDT - non-destructive testing and local mechanical properties of castings) and simulation tests (Procast, ANSYS) have shown how the properties gradient influences on the safety factor distribution in the casting subjected by chosen load.