Zhejiang Ruifeng Machinery Equipment Co., Ltd.
Contact person: Mr. Ma
Mobile phone: 18905728938
Address: 88 Tianxin Road, Xinshi Town, Deqing County
Three Processes in Electroplating Surface Treatment
Nowadays, an advanced plating surface treatment process generally includes three processes: heating, heat preservation and cooling, sometimes only heating and cooling. These processes are interlinked and uninterrupted. There are many heating methods for metal heat treatment. The earliest method is to use charcoal and coal as heat sources, and then to use liquid and gas fuels. The application of electricity makes heating easy to control and no environmental pollution. These heat sources can be directly heated or indirectly heated by molten salts or metals or even floating particles.
When metal is heated, the workpiece is exposed to air, and oxidative decarbonization (i.e. the carbon content on the surface of steel parts decreases) often occurs, which has a negative impact on the surface performance of the parts after heat treatment. Therefore, metals should be heated in controllable or protective atmosphere, molten salt and vacuum. Coatings or packaging can also be used for protective heating.
Heating temperature is one of the important technological parameters of heat treatment process. Selecting and controlling heating temperature is the main problem to ensure the quality of heat treatment. The heating temperature varies with the treated metal materials and the purpose of heat treatment, but it is generally heated to a characteristic transition temperature above, in order to obtain high temperature structure. In addition, the transformation takes a certain time, so when the surface of the metal workpiece reaches the required heating temperature, it must also maintain a certain time at this temperature, so that the internal and external temperatures are consistent, so that the transformation of the microstructures 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. Generally, there is no heat preservation time, while 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 according to different processes, mainly controlling the cooling rate. Generally, the cooling speed of annealing is the slowest, normalizing is faster and quenching is faster. But there are different requirements for different kinds of steel. For example, air-hardened steel can be hardened at the same cooling rate as normalized steel. Degree and toughness, the process of combining quenching and high temperature tempering, is called tempering. After quenching some alloys to form supersaturated solid solution, they are kept at room temperature or at a slightly higher appropriate temperature for a longer time to improve the hardness, strength or electrical magnetism of the alloys. Such a heat treatment process is called ageing treatment.
The method of combining pressure processing deformation with heat treatment effectively and tightly is called deformation heat treatment, which can make the workpiece get a good combination of strength and toughness. The heat treatment in negative pressure atmosphere or vacuum is called vacuum heat treatment. It can not only make the workpiece non-oxidized and non-decarbonized, keep the surface of the workpiece clean after treatment, improve the performance of the workpiece, but also penetrate into the infiltrating agent to carry out chemical heat treatment. Li.