What are the steps of hardware parts heat treatment process.
The cnc processing of hardware parts often requires heat treatment. Different materials have different heat treatment processes, and the effect is different. How many processes for heat treatment? Following let SWKD describle to you:
The heat treatment process generally includes three processes, which are heating, heat preservation, and cooling. Sometimes there are only heating and cooling two processes These processes are connected and uninterrupted.
Heating is one of the important processes of heat treatment. There are many heating methods for metal parts. The first was to use charcoal and coal as the heat source, and then use liquid and gas fuels. The application of electricity makes heating easy to control without environmental pollution. These heat sources can be used for direct heating, and can also be indirectly heated by molten salt or metal, and even floating particles.
The metal is often oxidize and decarburize during heated, because the workpiece is exposed to the air,(the carbon content of the surface decreases), which has a very unfavorable effect on the parts surface after heat treatment. Therefore, metals should generally be heated in a controlled atmosphere or maintenance atmosphere, molten salt and vacuum, and maintenance heating can also be performed by coating or packaging methods.
The heating temperature of the high vacuum sintering furnace is one of the important process parameters of the heat treatment process. The selection and control of the heating temperature is the primary issue to ensure the quality. The heating temperature varies with the metal material and the purpose of the heat treatment, but it is generally heated above the phase transition temperature to obtain a high temperature arrangement. Other transformations require a certain time. Therefore, when the surface of the metal workpiece reaches the required heating temperature, it must be maintained at this temperature for a certain time, so that the internal and external temperatures are common, and the microscopic arrangement is completely transformed. This time is called the heat preservation time. When high-energy density heating and surface heat treatment are used, the heating speed is extremely fast, and there is generally no heat preservation time, while the heat preservation time of chemical heat treatment is often longer.
Cooling is also an indispensable process in the heat treatment process. The cooling method varies with the process. The first is to control the cooling rate. Generally, annealing has the slowest cooling rate, normalizing cooling rate is faster, and quenching cooling rate is faster. However, there are different requirements due to different steel grades. For example, hollow hard steel can be quenched with the same cooling rate as normalizing.
Metal heat treatment processes can be roughly divided into three categories: overall 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 heat treatment processes are selected for the same metal to obtain different arrangements and then have different properties. Steel is the most widely used metal in industry, and the microscopic arrangement of steel is also the most messy, so the variety of steel heat treatment processes is complicated.
