1, Annealing treatment
The function of annealing treatment is to eliminate casting stress and internal stress caused by machining of castings, stabilize the shape and size of the processing parts, and make part of the Si crystalglobulization of the Al-Si alloy, and improve the plasticity of the alloy. Its process is: the aluminum alloy casting suture to 280-300 degrees C, insulation 2-3h, with the furnace cooling to room temperature so that the solid solution slowly decomposes, the second point of aggregation, so as to eliminate the internal stress of the casting, to achieve a stable size, improve plasticity, reduce deformation, warping purposes.
2, Quenching
Quenching is to heat aluminum alloy castings to a higher temperature (generally close to the melting point of the common crystal, more than 500 degrees C above), and keep warm 2h or more, so that the soluble phase in the alloy is fully dissolved. Then, quickly quench into the water at 60-100 degrees C, so that the casting swerved cold, so that the reinforced components in the alloy to maximize dissolution and fixed to room temperature. This process is called quenching, also known as solid-soluble or cold treatment.
3, Aging treatment
Aging treatment, also known as low temperature tempering, is the hardened aluminum alloy castings heated to a certain temperature, keep warm for a certain time out of air cold until room temperature, so that the oversaturated solid sepsis decomposition, so that the alloy substrate tissue stable process.
The aging treatment is divided into two categories: natural aging and artificial aging. Natural aging refers to the aging of aging at room temperature. The labor aging is divided into three kinds of incomplete labor aging, complete labor aging and overaging.
1) Incomplete artificial aging: heating the casting to 150-170 degrees C, keep warm for 3-5 hours, in order to obtain better tensile strength, good plasticity and toughness, but less corrosion resistance heat treatment process.
2) Full artificial aging: Heat the casting to 175-185 degrees C and keep warm for 5-24 hours to obtain sufficient tensile strength (i.e. maximum hardness) but low elongation of the heat treatment process
3) Overage: heating the casting to 190-230 degrees C, keeping warm for 4-9 hours, so that the strength is reduced, plasticity has been improved, in order to obtain better stress resistance, corrosion resistance process, also known as stabilization tempering.