Annealing treatment involves heating the aluminum alloy castings to a relatively high temperature, typically around 300 degrees Celsius, holding for a certain time, and then cooling with the furnace to room temperature. This process is referred to as annealing. During annealing, the solid solution undergoes decomposition, secondary phase particles aggregate, internal stresses are eliminated, dimensional stability is ensured, deformation is reduced, and moldability is increased.

Solution treatment entails heating the castings to between 300 and 500 degrees Celsius, holding for approximately two hours, fully dissolving the soluble phases within the alloy, followed by quenching in water to achieve maximum dissolution of strengthening phases in the alloy and locking them in place to the test. This process is called quenching, also known as heat treatment or cold treatment.

Aging treatment, also known as low-temperature tempering, involves heating the previously quenched aluminum alloy castings to a specific temperature, holding for a certain time, and then cooling to room temperature outside the room, stabilizing the structure of the alloy. Under aging refers to using a lower aging temperature or shorter holding time to achieve optimal comprehensive mechanical properties, higher strength, good plasticity, and toughness. Complete artificial aging refers to using a higher aging temperature and longer holding time to achieve higher hardness.

Over-aging refers to heating for aging treatment at a higher temperature to achieve good stress corrosion resistance, stable structure, and geometric dimensions. Cyclic treatment refers to cooling the aluminum alloy castings to minus 50 degrees Celsius or minus 70 degrees Celsius, or lower, and holding for two to three hours, then heating the castings to below 350 degrees Celsius, causing repeated contraction and expansion of the solid solution lattice in the alloy, causing slight displacement of the crystal grains of various elements to achieve a stable state. This repeated heating and cooling heat treatment process is called cyclic treatment, mainly used in the manufacture of precision parts, and general castings do not undergo such treatment.

*Code T1, artificial aging, aims to increase hardness, improve processing performance, and enhance the strength of alloys such as ZL104 and ZL105.

*Code T2, annealing, aims to eliminate internal stresses, remove work hardening caused by machining, improve dimensional stability, and increase alloy plasticity.

*Code T4, solution treatment, aims to increase strength and hardness, achieve maximum plasticity, and good corrosion resistance.

*Code T5, solution treatment + under aging, used to achieve sufficiently high strength while maintaining high plasticity, but with decreased corrosion resistance.

*Code T6, solution treatment + full aging, used to achieve maximum strength, but with reduced plasticity and corrosion resistance.

*Code T7, solution treatment + stabilization tempering, aims to improve dimensional stability and corrosion resistance while maintaining high mechanical performance.

*Code T8, solution treatment and softening tempering, aims to achieve dimensional stability, improve plasticity, but reduce strength.

     Inadequate Mechanical Properties: Exhibits as low elongation in annealed state; inadequate tensile strength and elongation in solution-treated state; inadequate tensile strength and elongation after aging.

1,During annealing, low annealing temperature or insufficient holding time, or too rapid cooling.

2,During solution treatment, temperature too low, insufficient holding time, excessive transfer time for quenching, or excessively high quenching water temperature.

3,Under aging or over aging due to high temperature or excessive time leading to high tensile strength but inadequate elongation, or low temperature and short time resulting in low tensile strength but excessive elongation.

4,Deviation in alloy chemical composition, such as exceeding upper limits of major components.

Re-annealing at higher temperature, or extending holding time, or strict cooling with the furnace.

Increase solution treatment temperature to upper limit range, or extend holding time, minimize transfer time for quenching while ensuring no deformation or cracking, lower quenching water temperature, or change quenching medium to "CL-1" organic quenching medium.

Adjust aging temperature and time after re-solution treatment.

E: lydia@welongchina.com.