Metallic materials include:
1, ferrous metals: also known as iron and steel materials, including the total impurity content & lt; 0.2% and carbon content of no more than 0.0218% of the industrial iron, carbon 0.0218% to 2.11% of the steel, carbon greater than 2.11% of cast iron. Broadly speaking, ferrous metals also include chromium, manganese and their alloys.
2, non-ferrous metals: is in addition to iron, chromium, manganese, all metals and their alloys, usually divided into light metals, heavy metals, precious metals, semi-metals, rare metals and rare earth metals, non-ferrous alloys are generally higher than the strength and hardness of the pure metal, and the resistance of resistance temperature coefficient is small.
3, special metal materials: including different uses of structural metal materials and functional metal materials. Among them are amorphous metal materials obtained through rapid condensation process, as well as quasi-crystalline, microcrystalline, nanocrystalline metal materials, etc.; and stealth, hydrogen, superconductivity, shape memory, wear-resistant, vibration damping and other special functional alloys, as well as metal-based composite materials.
Extended information
Performance:
1, physical properties
The physical properties of metal materials are mainly density, melting point, thermal expansion, thermal conductivity, electrical conductivity and magnetism. Due to the different uses of machine parts, the physical properties of its requirements are different. For example, aircraft parts often choose the density of aluminum, magnesium, titanium alloy to manufacture; design of motors, electrical parts, often to consider the conductivity of metal materials.
The physical properties of metal materials sometimes have a certain impact on the processing technology. For example, the thermal conductivity of high-speed steel is poor, forging should be used at a low rate to heat up the temperature, otherwise it is easy to produce cracks; and the thermal conductivity of the material has a significant impact on the temperature rise of cutting tools. Another example, tin-based bearing alloys, cast iron and cast steel melting point is different, so the selected melting equipment, casting materials are very different.
2, chemical properties
The chemical properties of metal materials mainly refers to the room temperature or high temperature, resistance to a variety of media erosion, such as acid, alkaline, oxidation resistance.
For corrosive media or machine parts working at high temperatures, due to corrosion than in the air or at room temperature is more intense, so in the design of such parts should pay special attention to the chemical properties of metal materials, and the use of good chemical stability of the alloy. Such as chemical equipment, medical appliances are often used to manufacture stainless steel, while the internal combustion engine exhaust door and power station equipment, some parts are often used to manufacture heat-resistant steel.
3, process performance
Process performance is the physical and chemical properties of metal materials and mechanical properties in the processing of a comprehensive reflection of whether it is easy to cold, hot processing performance. According to the different methods of technology, can be divided into casting, malleable, welding and cutting and processing.
In the design of parts and selection of process methods, should consider the process performance of metal materials. For example, gray cast iron casting performance is excellent, is widely used in the manufacture of castings is an important reason, but their malleability is extremely poor, can not be forged, and its weldability is also poor. Another example, mild steel has excellent weldability, while high carbon steel is poor, so welded structures are widely used mild steel.
Baidu Encyclopedia-Metallic Materials