With the continuous development of social economy, many industries gradually rise, cast steel gear is an indispensable part of all machinery. The quality and hardness of cast steel gears have a crucial influence on the overall performance of mechanical equipment. The quality of mechanical equipment directly affects the smooth operation of various projects. There are many factors that affect the quality and hardness of cast steel gears, among which heat treatment is one of the most important. Heat treatment can be divided into preheating treatment and post heat treatment.
Preheat treatment can change the properties of cast steel gears, while later heat treatment can fix the shape of gears. Through two kinds of heat treatment, the surface structure of cast steel gear can be more perfect, the hardness and wear resistance can be improved to a certain extent.
With the continuous development of science and technology, mechanical equipment also put forward higher requirements for gear performance. Cast steel is the most commonly used material for gear manufacturing in China. Each material has different performance after heat treatment. Therefore, further analysis should be made on the heat treatment effect of cast steel gear to improve the performance of cast steel gear to a certain extent and better serve the operation of mechanical equipment.
Explore the influence of heat treatment on the surface structure and hardness of cast steel gears
At present, the quality of cast steel gear is not up to standard in the mechanical equipment of our country, and the mechanical failure caused by gear failure often occurs. Cast steel gears can break due to insufficient tensile stress or damage due to overuse. The main reason for this phenomenon is the problem of surface structure and core hardness. Generally speaking, with the improvement of the hardness of the cast steel gear, its wear resistance and tensile strength can be enhanced, and the service life of the cast steel gear will be longer, so the operation effect will be better . At the same time, cast steel gears also have higher requirements for surface structure. Even if the hardness of the core part of the gear meets the requirements, the surface structure and properties of the gear are not up to the standards. It is very easy to have fatigue operation of cast steel gears. The tensile stress and the overall toughness of the gear are reduced, which further deepens the fatigue process of the gear. Heat treatment can effectively solve this problem. It can be seen that the importance of heat treatment process, the relevant workers should pay attention to this process.
In recent years, great progress has been made in the research of cast steel gears in China, but there are still many deficiencies in the practical application process, which need to be improved in practice. Before and after heat treatment, the surface structure of cast steel gear will change greatly, and the internal elements will be rearranged to achieve better performance and reduce mechanical equipment failure. Heat treatment needs to ensure a certain temperature. In the process of heat treatment, once the temperature is lower than the limit value, the temperature should be supplemented. Through the standard heat treatment process, the performance of cast steel gears can be improved, the hardness of gears can be increased, and abnormal influence can be avoided. The whole heat treatment process needs to be standardized, including operation specification and equipment selection.
Before heat treatment, the surface structure of cast steel gear is ferrite and pearlite, and the distribution is uniform.
After heat treatment, another form of martensite is formed on the surface, and its hardness is also improved, so as to reduce the wear and damage of cast steel gears in use. After the heat treatment, it is necessary to use ultrasonic to detect the cast steel gear to ensure that the quality of the gear can meet the use requirements of mechanical equipment.
Experimental results and analysis
The surface structure of the cast steel gear is a part of martensite and a small amount of austenite. In the experiment, the closer to the surface of the gear, the less austenite, while the martensite is strip. The closer to the core of the gear, the more obvious the shape of the martensite strip is, and it becomes coarser and larger. Martensite and austenite are important indexes to measure the hardness of cast steel gears. By measuring the content of martensite and austenite on the surface of cast steel gears, the hardness of cast steel gears can be effectively analyzed. The hardness change of cast steel gear in the experiment is shown in the figure.
It can be seen from the figure that the surface structure hardness of cast steel gear decreases with the increasing distance from the surface. Within a certain range, the hardness value tends to be stable. Through heat treatment, the element content and properties of cast steel gears will change. In cast steel gears, the steel content is large. If the steel content suddenly decreases, the hardness of gears will be affected.
The properties of cast steel gears are more stable through heat treatment, and the structure and properties are shown in Table 1.
After heat treatment, the surface structure and hardness of the cast steel gear will change greatly. Compared with the cast steel gear without heat treatment, the wear resistance, fatigue resistance and service life of the cast steel gear can be increased by about one third.
At the same time, the surface structure of cast steel gear will also change to avoid cracking and aging. Most of the traditional processes only focus on increasing the riser to supplement the hot spot between the heavy spoke plate and the rim, which greatly reduces the technological yield of the cast steel gear. Strictly control the original structure and heat treatment parameters of gear to minimize the generation of cracks and the pollution of quenching oil.
Cast steel is a new material. Because of its unique characteristics, cast steel gears are widely used in many industries. In mechanical equipment, if the cast steel gear is damaged suddenly, it is likely to bring huge property loss .
In order to ensure the quality of cast steel gears, deep processing and heat treatment should be carried out. In this way, the surface structure of cast steel gears is more stable and the hardness is also improved. Reduce the maintenance and remanufacturing of cast steel gear, save cost and provide higher guarantee for the operation of mechanical equipment.