The Types Of Aluminum And Aluminum Alloys

อลูมิเนียมบริสุทธิ์

The characteristic of pure aluminum is its low density, which is 2.72g/cm ³, only about one-third of the density of iron or copper. Good conductivity and thermal conductivity, รองจากเงินและทองแดงเท่านั้น. คุณสมบัติทางเคมีของอะลูมิเนียมมีความว่องไวมาก.

ในอากาศ, the surface of aluminum can combine with oxygen to form a dense Al2O3 protective film, which prevents further oxidation of aluminum. ดังนั้น, อลูมิเนียมมีความต้านทานการกัดกร่อนในอากาศและน้ำได้ดี, but it cannot resist acid, ด่าง, และการกัดกร่อนของเกลือ.

Aluminum has a face centered cubic lattice and good plasticity (ง=50%, ψ=80%). It can be processed into profiles such as wires, จาน, แถบ, and pipes through cold or hot pressure, but its strength is not high, σb＝80MPa， After cold processing, σb＝(150～250)MPa。 So pure aluminum is mainly used to make wires, สายเคเบิล, แผ่นระบายความร้อน, and daily necessities or alloys that require rust and corrosion resistance but low strength requirements.

Commercial purity aluminum is not as pure as chemical purity aluminum, as it contains impurities such as Fe, และ, เป็นต้น. to varying degrees. The more impurities are present in aluminum, the lower its conductivity, การนำความร้อน, resistance to atmospheric corrosion, and plasticity.

The grades of industrial pure aluminum in our country are formulated based on the limit of impurities, such as L1 L2、L3……。 L is the first Chinese Pinyin character for “อลูมิเนียม”, and the higher the sequence number attached after it, the lower its purity.

อลูมิเนียมอัลลอยด์

Pure aluminum has low strength and is not suitable as a structural material. To improve its strength, the most effective method is to add alloying elements such as Si, ลูกบาศ์ก, มก, ล้าน, เป็นต้น. เพื่อทำอลูมิเนียมอัลลอยด์ (แอโรไลต์). These aluminum alloys have high strength, but still have ความหนาแน่นต่ำ, มีความแข็งแรงจำเพาะสูงเป็นพิเศษ (i.e. อัตราส่วนของขีดจำกัดความแข็งแรงต่อความหนาแน่น), as well as good thermal conductivity and corrosion resistance.

Classification of Aluminum Alloys

ตามองค์ประกอบและลักษณะกระบวนการผลิตของโลหะผสมอลูมิเนียม, they can be divided into two categories: อลูมิเนียมอัลลอยด์ที่มีรูปร่างผิดปกติและโลหะผสมอลูมิเนียมหล่อ.
When the composition of the alloy is less than D/point, it can form a single-phase solid solution structure when heated, with good plasticity and suitable for pressure processing, hence it is called deformed aluminum alloy.

Aluminum alloys with a composition smaller than the F-point in deformation, whose solid solution composition does not change with temperature and cannot be strengthened by heat treatment, are called heat treatment unreinforced aluminum alloys; An alloy with a composition between F and D/, whose solid solution composition changes with temperature, can be strengthened by heat treatment, hence it is called an aluminum alloy that can be strengthened by heat treatment.

Alloys with a composition greater than D/point, low melting point eutectic structure, good flowability, suitable for casting, are called cast aluminum alloys, but not suitable for pressure processing.

Deformable aluminum alloys can also be classified into rust proof aluminum, hard aluminum, ultra hard aluminum, and forged aluminum according to their main performance characteristics.
Casting aluminum alloys can also be classified according to the different main alloying elements: Al Si, Al Cu, Al Mg, Al Zn, เป็นต้น.

ลักษณะการอบชุบด้วยความร้อนของอลูมิเนียมอัลลอยด์

Aluminum alloys can not only improve their strength through cold deformation work hardening, but also further enhance their strength through heat treatment – “อายุที่แข็งตัว” วิธี.
กลไกการรักษาความร้อนของอลูมิเนียมอัลลอยด์แตกต่างจากเหล็กกล้า. หลังจากดับแล้ว, the hardness and strength of steel immediately increase, ในขณะที่ความเป็นพลาสติกลดลง. Aluminum alloys with components between F and D/can be heated to the alpha phase region, insulated, and quenched by water cooling to obtain supersaturated alpha solid solutions at room temperature. Their strength and hardness cannot be immediately increased, but their plasticity is significantly improved. กระบวนการนี้เรียกว่าการชุบแข็งหรือการบำบัดด้วยสารละลาย.

Due to the instability of the supersaturated solid solution obtained after quenching, there is a tendency to precipitate a second phase (ขั้นตอนการเสริมสร้างความเข้มแข็ง). After being left at room temperature for a period of time or heated at low temperatures, atoms have the ability to move within the lattice and gradually transition to a stable state, resulting in a significant increase in strength and hardness, while plasticity decreases. The phenomenon of further strengthening of the alloy after solid solution treatment over time is called “อายุที่แข็งตัว” หรือ “อายุที่แข็งตัว”. The aging process carried out at room temperature is called natural aging, while the aging process carried out under heating conditions is called artificial aging.

Deformable aluminum alloy

1. Anti rust aluminum alloy

องค์ประกอบการผสมหลักคือ Mn และ Mg. This type of alloy is a single-phase solid solution after forging and annealing, so it has good corrosion resistance and plasticity. The rust proof aluminum grade is represented by the Chinese Pinyin prefix “LF” followed by a sequential number. เช่น LF5, แอลเอฟ11, แอลเอฟ21, เป็นต้น. โลหะผสมประเภทนี้ส่วนใหญ่จะใช้สำหรับการรีด, การเชื่อม, or corrosion-resistant structural components with low loads, such as oil tanks, ท่อ, สายไฟ, light load skeletons, and various household appliances. All kinds of anti rust aluminum alloys are aluminum alloys that cannot be strengthened by heat treatment. To improve the strength of the alloy, cold pressure processing can be applied, ซึ่งสามารถทำให้เกิดการแข็งตัวของงานได้.

2. อลูมิเนียมอัลลอยด์แข็ง

Duraluminum is basically an Al Cu Mg alloy with a small amount of Mn. Various types of duralumins can be strengthened by aging, แต่ความต้านทานการกัดกร่อนไม่ดี, โดยเฉพาะในน้ำทะเล. ดังนั้น, hard aluminum components that require protection are wrapped with high-purity aluminum on the outside to make aluminum coated hard aluminum materials. Hard aluminum grades use the Chinese Pinyin prefix “ลี” followed by a sequential number, เช่น LY1 (หมุดย้ำอลูมิเนียมแข็ง), LY11 (อลูมิเนียมแข็งมาตรฐาน), และ LY12 (อลูมิเนียมแข็งที่มีความแข็งแรงสูง).
Hard aluminum is a structural material with high specific strength, which has been widely used in the aviation industry and instrument manufacturing.

3. อลูมิเนียมอัลลอยด์ที่แข็งเป็นพิเศษ (SD อัลลอยด์)

It is an Al Cu Mg Zn alloy, which is made by adding Zn to hard aluminum. This type of alloy is currently the strongest aluminum alloy, with higher specific strength, hence it is called superhard aluminum. The disadvantage is also poor corrosion resistance, which can increase the artificial aging temperature or aluminum coating.
The grade of ultra hard aluminum alloy is represented by the Chinese Pinyin prefix “ลค” followed by a sequential number. LC4, LC6, เป็นต้น. are commonly used to manufacture important components with high stress, such as aircraft beams.

4. Forged aluminum alloy

It is an Al Cu Mg Si alloy with a variety of alloying elements, but the content of each element is relatively low, thus it has good thermoplastic and corrosion resistance, and its strength is comparable to that of hard aluminum. After quenching and aging, the strength can be improved.
The grade of forged aluminum alloy is represented by the Chinese Pinyin prefix “แอล.ดี” followed by a sequential number, เช่น LD5, แอลดี7, เป็นต้น. Due to its excellent forging performance, it is mainly used for forging or forging parts that bear heavy loads on aircraft or diesel locomotives.

Cast aluminum alloy

อลูมิเนียมอัลลอยด์หล่อมีหลายประเภท, among which aluminum silicon alloys have good casting performance, ความแข็งแรงเพียงพอ, และความหนาแน่นต่ำ, and are widely used, บัญชีมากกว่า 50% of the total production of cast aluminum alloys. Al Si alloys containing Si (10-13)% are the most typical aluminum silicon alloys, belonging to eutectic composition, commonly known as “silicon aluminum alloys”.

The grade of cast aluminum alloy is represented by the Chinese Pinyin prefix “Z”+Al+other major element symbols and percentage content of the word “cast”. ตัวอย่างเช่น, ZAlSi12 represents cast Al Si alloy containing 12% และ.

The code for the alloy is represented by the Chinese Pinyin prefix “ซล” ของ “อลูมิเนียมหล่อ” followed by three digits. The first digit represents the alloy category, while the second and third digits indicate the sequence number of the alloy.

Example ZL102 represents the casting aluminum alloy of Al Si series No. 2.
Casting aluminum alloy is generally used to produce parts that are lightweight, ทนต่อการกัดกร่อน, have complex shapes, and have certain mechanical properties. Such as aluminum pistons, instrument housings, water-cooled engine cylinder components, crankcases, เป็นต้น.