According to GB / T 1173-1995, the cast aluminum alloy code is composed of the letters “Z” and “L” (they are the first letters of Chinese Pinyin of “cast” and “aluminum” respectively) and three Arabic numerals after them. The first number after ZL indicates alloy series, in which 1, 2, 3 and 4 indicate Al Si, Al Cu, Al Mg and Al Zn series alloy respectively, and the second and third numbers after ZL indicate sequence number.
High quality alloy with the letter “a” after the number.
The alloy casting method and modification code are as follows:
J — metal mold casting;
R — investment casting;
K — shell casting;
B – metamorphic treatment.
The alloy status code is:
F — as cast;
T1 – artificial aging;
T2 – annealing;
T4 — solution treatment plus natural aging;
T5 — solution treatment plus incomplete artificial aging;
T6 — solution treatment plus complete artificial aging;
T7 — solution treatment plus stabilization treatment;
T8 — solution treatment plus softening treatment.
See GB / t1173-1995 for the chemical composition of cast aluminum alloy and GB / t1173-1995 for the allowable content of impurities.
The Al Si alloy which needs to be modified is treated with sodium (containing sodium salt). Under the premise of not reducing the service performance of the alloy, other modifiers or modification methods are allowed. W (Cu) in ZL101 alloy is less than 0.1% when it is used in marine environment. The silicon content of ZL203 alloy is allowed to be 3.0% in metal mold casting.
When the w (FE) of ZL105 alloy is more than 0.4%, the mass fraction of manganese should be more than half of iron. When ZL201 and zl201a alloys are used to make the parts working at high temperature, w (Zr) should be added = 0.05% ~ 0.20%.
In order to improve the mechanical properties, ZL101 and ZL102 alloy are allowed to contain y = 0.08% ~ 0.20%; ZL203 alloy is allowed to contain w (TI) = 0.08% ~ 0.20%. At this time, their iron content w (FE) < 0.3%.
Aluminum alloy products in contact with food: not allowed to contain beryllium; w (as) < 0.015%; w (Zn) < 0.3%; w (PB) < 0.15%.
When the impurity content is expressed by the sum of impurities, the mass fraction of each unlisted element shall not be greater than 0.05% unless otherwise specified.
See GB / t1173-1995 for the mechanical properties of cast aluminum alloy. Single cast sample is used to test the mechanical properties. The diameter of the sample is (12 ± 0.25) mm, and the gauge distance is five times of the diameter. One or three body samples can also be cut from the same furnace casting for testing.
Solution heat treatment of cast aluminum alloy
See Table 11 for solution treatment specifications of cast aluminum alloy.
During solution treatment, the charging temperature is generally below 300 ℃, and the heating rate (rising to solution temperature) should be 100 ℃ / h. In the solution treatment, if the stage insulation is needed, it is not allowed to stay cooling between the two stages, and it needs to be directly raised to the second stage temperature. After solution treatment, the quenching transfer time is controlled between 8 s and 30 s (depending on the type of alloy and parts). The water temperature of quenching medium is determined by the manufacturer according to the type of alloy and parts. The cooling medium after aging is room temperature air.