foreign classification of cast aluminum alloys subdivides them according to the main alloying elements into eight series:
1hh.h series - Aluminum, no less 99,00 %
2hh.h series - Copper
series 3xx.x - silicon (with copper and magnesium)
4hh.h series - silicon
5hh.h series - Magnesium
7hh.h series - Zinc
series 8hh.h - lead
other elements - 9hh.h series.
Castings from cast aluminum alloys are produced by virtually all casting methods: in sand molds, chill, the low and high pressure, and so on. Most aluminum casting is heat treated. The quality control of cast aluminum products play an important role to control their microstructure.
Microstructure of cast aluminum alloys series 2hh.h
Usually the aluminum alloys of this series have the worst casting properties, particularly low fluidity. castings continuity control light microscope on polished samples without etching. Structural components are essentially the same, that of wrought alloys 2xxx series.
Microstructure of cast aluminum alloys series 5hh.h
Alloys of this series are known for high corrosion resistance, good machinability and attractive appearance after anodizing. Identify the structure of the casting 0,5 %-a saline solution of hydrofluoric acid.
Microstructure of silicon aluminum casting alloys (series 3xx.x and 4xx.x)
Casting aluminum alloys with silicon as a main alloying element are the most popular. They have the best casting performance when compared with other aluminum alloys. Moreover, These alloys have high corrosion resistance, weldability and low density. Their microstructure consists essentially of silicon particles mesh, interdendritic are formed from aluminum-silicon eutectic. This structure is etched 0,5 %-a saline solution of hydrofluoric acid. After the solution-annealed products appear spheronization and isolation of the aging process.
Microstructure of cast aluminum alloys series 7hh.h and 8hh.h
Typically 7hh.h series alloys have good mechanical machinability and high melting point. Therefore, they are used for parts, who are going to solder. These alloys during casting often susceptible to cracking. Casting aluminum alloys 8hh.h series, containing silicon, commonly used for bearings. Etching patterns produce 0,5 %-a saline solution of hydrofluoric acid.
A source: TALAT 1202