Aluminum is a chemical element. Its chemical symbol is al and its atomic number is 13. Aluminum is the most abundant metal element in the earth's crust, ranking third only to oxygen and silicon. Among the metal varieties, it is the second largest type of metal after steel. It is a competitive metal in engineering applications. Aluminum alloys used in aircraft have high requirements for strength, hardness, toughness, fatigue resistance, and plasticity.In addition to the Aluminum Seat series,...