What is the spring heat treatment process? Some people should know that the spring heat treatment is a metal heat treatment process that uses heating, cooling, heat preservation and other means to arrange and function the arrival of materials. The heat treatment process can be divided into four types. The Guoyang Xiaobian of Dongguan spring factory will take us to know what the heat treatment process of metal springs is!?
1、 Classification of spring heat treatment process
The spring heat treatment process can be generally 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. The same spring adopts different heat treatment processes to obtain different structures and thus have different properties. Steel is a metal used in industry, and the microstructure of steel is complex, so there are many kinds of heat treatment processes for steel.
Integral heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at an appropriate speed to obtain the required metallographic structure to change its overall mechanical properties. There are four basic processes for the overall heat treatment of steel: annealing, normalizing, quenching and tempering.
2、 Spring heat treatment process
The spring heat treatment process generally includes three processes: heating, heat preservation and cooling, and sometimes only two processes are heating and cooling. These processes are interconnected and cannot be interrupted.
Spring heating is one of the important processes of heat treatment. There are many heating methods for spring heat treatment. Charcoal and coal are used as heat sources, and liquid and gas fuels are used recently. The application of electricity makes heating easy to control and no environmental pollution. These heat sources can be used for direct heating or indirect heating by molten salt or metal or even floating particles.
When the spring is heated, the workpiece is exposed to the air, and oxidation and decarburization often occur (that is, the carbon content on the surface of steel parts is reduced), which has a very adverse effect on the surface performance of the parts after heat treatment. Therefore, the metal should usually be heated in a controlled atmosphere or protective atmosphere, molten salt and vacuum, and can also be protected by coating or packaging.
Heating temperature is one of the important process 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 metal material to be treated and the purpose of heat treatment, but it is generally heated to above the phase transformation temperature to obtain a high-temperature structure. In addition, the transformation takes a certain time. Therefore, when the surface of the metal workpiece reaches the required heating temperature, it must be kept at this temperature for a certain time to make the internal and external temperatures consistent and complete the transformation of the microstructure. This time is called the holding time. When high-energy density heating and surface heat treatment are adopted, the heating speed is very fast, and generally there is no holding time, while the holding time of chemical heat treatment is often long.
Cooling is also an indispensable step in the heat treatment process. The cooling method varies with different processes, mainly by controlling the cooling speed. Generally, the cooling speed of annealing is slow, the cooling speed of normalizing is faster, and the cooling speed of quenching is faster. However, there are different requirements due to different steel types. For example, air hardened steel can be quenched at the same cooling rate as normalizing.
