Alloy classification and generality
Classification of alloys
According to the name of the main metal with a large content in the alloy, it is classified as a certain alloy. For example, a copper alloy with a high copper content is mainly used to maintain the properties of copper.
Depending on the structure, the main types of alloys are:
(1) a mixture alloy (eutectic mixture), an alloy formed by crystallizing the components of the alloy when the liquid alloy is solidified, such as solder, cadmium-cadmium alloy, etc.;
(2) a solid solution alloy, an alloy forming a solid solution when the liquid alloy solidifies, such as a gold-silver alloy;
(3) An intermetallic compound, an alloy in which each component forms a compound with each other, such as brass composed of copper or zinc (β-brass, γ-brass, and ε-brass).
Many properties of alloys are superior to pure metals, so alloys are mostly used in applied materials (see Ferroalloys, Stainless Steels).
Alloy passability
All types of alloys have the following general characteristics:
(1) Most alloys have a melting point lower than the melting point of any of the constituent metals of the composition;
(2) The hardness is generally greater than the hardness of any of the components; (Special case: the sodium-potassium alloy is liquid, used for the thermal conductivity agent in the atomic reactor)
(3) The electrical conductivity and thermal conductivity of the alloy are lower than those of any component. With this property of the alloy, high resistance and high thermal resistance materials can be produced. It is also possible to manufacture materials with special properties.
(4) Some have strong corrosion resistance (such as stainless steel), such as 15% chromium and 9% nickel in iron to obtain a corrosion-resistant stainless steel, suitable for the chemical industry.
2. Common alloys
Ductile iron, manganese steel, stainless steel, brass, bronze, white copper, solder, hard aluminum, 18K gold, 18K white gold.
The mechanical screw was the first parallel threaded drive screw used in ancient clocks and firearms. In 1900s, it was the king of small, inexpensive, low end Screws and fasteners. Machine screws have changed a lot over the past 100 years; unless the screws are very small or small in number and not optimized, the threads are rolled up and will not be cut. In addition to the miniature screws, the screw head and driver are cold-forged again.
Head and drive type machine screws have a variety of drives and heads to choose from. The most popular heads are Pan and Countersunk, although there are various types of heads to choose from. These include slotted, Phillips, Pozi, hexagon wrench, hexagon wrench, Torx hexagon star, square drive socket head and safety head, easy to assemble but difficult to disassemble.
Mechanical Screws Application Mechanical screws are used to attach parts to machines, mechanical tools, and have many functions in telephones, electrical appliances, electronic equipment, and vehicles.
Mechanical screws low-strength steel, brass, aluminum and stainless steel.
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