On 2018-08-08 14:48:54
On 2018-08-08 14:47:24
On 2018-08-08 11:45:46
Metal: material having opaque, metallic luster, good heat and electrical conductivity, ductile and malleable properties, and whose conductivity decreases with increasing temperature. A solid (that is, a crystal) in which the atoms are arranged regularly.
Alloy: a substance of metallic properties formed by melting or otherwise combining a metallic element with another or more elements.
Phase: homogeneous components of an alloy that are of the same chemical composition, in the same state of aggregation, and separated from each other by an interface.
Solid solution: a solid metal crystal in which the atoms (compounds) of one (or more) constituent dissolve into the lattice of another constituent while retaining the lattice type of the other constituent.
Solid solution strengthening: because solute atoms enter the gap or junction of the solvent lattice, the lattice distortion, the hardness and strength of the solid solution increased, this phenomenon is called solid solution strengthening phenomenon.
Metal heat treatment process can be divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment. According to the difference of heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. With different heat treatment processes, different tissues can be obtained for the same metal, which has different properties. Steel is a widely used metal in industry, and the microstructure of steel is complex, so there are many kinds of heat treatment processes.
Integral heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at an appropriate rate to change its overall mechanical properties. There are four basic processes for the heat treatment of steel: annealing, normalizing, quenching and tempering.
Annealing is to heat the workpiece to the appropriate temperature, according to the material and the size of the workpiece with different holding time, and then slow cooling, the purpose is to make the metal inside the tissue to achieve or close to the equilibrium state, to obtain good process performance and service performance, or for further quenching for the organization preparation. Normalizing is to heat the workpiece to a suitable temperature and then cool it in the air. Normalizing is similar to annealing, but the obtained microstructure is relatively fine. It is often used to optimize the cutting performance of low-carbon materials, and sometimes it is also used for the subsequent heat treatment of some parts with low requirements.