Metal heat treatment service
Heat treatment center
Development and research of high technology, high technology and high quality heat treatment industrialization process is the goal. Adopt advanced and flexible operation mechanism, strict enterprise management, quality management, with a variety of practical personnel. Continuous innovation of traditional heat treatment process, quality testing based on the national heat treatment table Committee standards, constantly improve! The use of international advanced testing equipment, strict control of the quality of heat treatment, so that the quality of further assurance and improvement! Advanced 1300mm vacuum high pressure gas quenching furnace, controllable atmosphere multi-purpose furnace, 6000mm super large quenching and tempering furnace, and dozens of conventional well furnace and other equipment! It can provide various processing service items such as vacuum quenching, vacuum carburizing, conventional carburizing, hard nitrogen, soft nitrogen, annealing and normalizing for various mechanical parts, spare parts, dies and dies.
Metal heat treatment process
Heat treatment process generally includes heating, insulation, cooling three processes, sometimes only heating and cooling two processes. These processes are interconnected and uninterrupted. Heating is one of the most important processes in heat treatment. There are many heating methods for heat treatment of metals. Charcoal and coal were used as heat sources, and then liquid and gas fuels were used. The application of electricity makes heating easy to control without environmental pollution. These heat sources can be directly heated, or indirectly heated by molten salts or metals, or even floating particles. When the metal is heated, the workpiece is exposed to the air and often oxidizes and decarbonizes (i.e. the carbon content on the surface of the steel parts decreases), which has a very adverse effect on the surface properties of the parts after heat treatment. Therefore, metals should usually be heated in controlled or protective atmosphere, molten salt and vacuum, or by coating or packaging. The heating temperature is one of the important technological parameters in the heat treatment process. Selecting and controlling the heating temperature is the main problem to ensure the quality of heat treatment. The heating temperature varies with the object of heat treatment and the metal material being treated, but it is generally heated above the phase change temperature to obtain high temperature microstructure. In addition, the transformation takes a certain time, so when the surface of the metal workpiece reaches the required heating temperature, it must be kept at this temperature for a certain period of time, so that the internal and external temperatures are consistent, so that the microstructure of the transformation is complete, this period is called holding time. When high energy density heating and surface heat treatment are used, the heating speed is very fast, and there is no heat preservation time in general, but the heat preservation time of chemical heat treatment is often longer.
Cooling is also an indispensable step in the process of heat treatment. Cooling methods vary with the process, mainly controlling the cooling rate. The cooling rate of general annealing is slow, normalizing cooling rate is faster, quenching speed is faster. But there are different requirements for different grades of steel, such as air-hardened steel can be normalized with the same cooling rate for hardening.
Metal heat treatment technology can be broadly divided into three categories: integral heat treatment, surface heat treatment and chemical heat treatment. According to the different heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. Different microstructure and properties can be obtained by different heat treatment processes for the same metal. Steel is widely used in industry, and the microstructure of steel is also complex, so there are many kinds of heat treatment process of steel. Integral heat treatment is a metal heat treatment process in which the workpiece is heated as a whole and then cooled at an appropriate rate to change its overall mechanical properties.
The overall heat treatment of steel consists of four basic processes: annealing, normalizing, quenching and tempering. Annealing is to heat the workpiece to a suitable temperature, according to the material and workpiece size with different holding time, and then slow cooling, the purpose is to make the internal structure of the metal to achieve or close to equilibrium, to obtain good technical performance and service performance, or to prepare for further quenching microstructure. Normalizing is to heat the workpiece to a suitable temperature and then cool it in the air. Normalizing effect is similar to annealing, but the obtained microstructure is fine, often used to improve the cutting performance of materials, and sometimes used as heat treatment for some parts with low requirements.
Quenching is the rapid cooling of the workpiece in water, oil or other inorganic salts, organic water solution and other quenching media after heating and holding. Hardened steel hardens but becomes brittle at the same time. In order to reduce the brittleness of steel, the quenched steel is kept for a long time at a suitable temperature above room temperature but below 650 C, and then cooled. This process is called tempering. Annealing, normalizing, quenching and tempering are the "four fires" in the whole heat treatment, in which quenching and tempering are closely related, often used together, indispensable. With the difference of heating temperature and cooling mode, the "four fires" have evolved different heat treatment processes. In order to obtain a certain strength and toughness, the quenching and high temperature tempering process is called quenching and tempering. Some alloys are quenched to form over-saturated solid solutions, which are kept for a long time at room temperature or at a slightly higher appropriate temperature to improve the hardness, strength or electrical magnetism of the alloys. Such a heat treatment process is called aging treatment.