Heat treatment of aluminum alloy castings is to choose a certain heat treatment standard, control heating speed to conduct heat preservation for a period of time when heating temperature rises to a certain corresponding value, then cool down at a certain speed to change alloy structure of aluminum alloy castings. The main purpose is to improve alloy mechanical property, corrosion resistance property and processing property to ensure dimensional stability. As every knows, the steel containing higher carbon content can immediately have quite high hardness but low plastic property after quenching. However, after aluminum alloy is quenched, its strength and hardness will not increase at once and its plastic property will increase to some extent instead of decreasing. But as for this kind of quenched aluminum alloy, its strength and hardness will increase significantly with plastic property decreasing obviously instead after storage for a period of time (4¡«6 days and nights). The phenomenon of aluminum alloy¡¯s significant increase in strength and hardness as time goes on is called aging. Aging can occur either at normal temperature which is called natural aging or within a certain temperature range (for example, 100¡«200¡æ) higher than ambient temperature, which is called artificial aging. Solid solution treatment (quenching) plus artificial aging upon aluminum alloy is generally called T6 heat treatment technology by people. |
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