One. What is heat treatment quenching medium
Heat treatment quenching medium refers to the medium used to rapidly cool metal materials for quenching. During the heat treatment process, through rapid cooling, the organizational structure of the metal can be changed to obtain the required physical and mechanical properties. Different metals and quenching requirements often require different quenching media.
Two. Common heat treatment quenching media
Different types of metals and quenching requirements require different media. The following are several common quenching media:
1. Water: Water is one of the most commonly used quenching media. Its cooling rate is very fast, which is its most significant feature. Rapid cooling can cause the metal to quickly change from a high-temperature state to a low-temperature state, thereby forming a higher hardness. organizational structure. This makes aqueous media particularly suitable for quenching applications where high hardness is required. But due to the rapid cooling rate of water, water-quenched metals generally have a higher hardness, but may also become relatively brittle. This makes water quenching suitable for some tool steels, spring steels, and other materials that require high hardness but can accept lower toughness.
2. Oil: Oil is another commonly used quenching medium. Oil cools more slowly than water, resulting in higher toughness and tensile strength. The cooling rate of oil is slower than that of water and is relatively mild, so the quenching speed can be controlled to produce a structural structure with appropriate hardness and toughness. Oil's moderate cooling rate makes it suitable for many different types of metallic materials. The slower cooling rate of oil relative to water reduces the risk of deformation and cracking of metal materials during quenching. Therefore, oil media is suitable for workpieces that need to reduce deformation and cracking.
3. Polymer solutions: Polymer solutions can provide moderate cooling rates. Because polymers have high viscosity, they can slow down the cooling rate of metal materials. This moderate cooling rate allows the polymer solution medium to provide moderate hardening capabilities while maintaining some toughness. In addition, the cooling rate of polymer solutions can be adjusted by changing the concentration and properties of the polymer in the solution. By adjusting the concentration and additives, the quenching speed of metal materials can be precisely controlled to meet different application needs.
4. Air: The heat treatment air medium cools relatively slowly compared to water, oil, or polymer solutions. Air has poor thermal conductivity and cannot absorb heat quickly like liquid media. Therefore, air quenching is milder and the cooling rate is slower. Air quenching can produce higher toughness and tensile strength due to the slower cooling rate. Metallic materials generally have a lower hardness after air cooling compared to water or oil quenching. Air media is therefore suitable for applications requiring toughness and low hardness, such as some mild steels.
5. Salt bath: Heat treatment salt bath medium is a heat treatment method in which metal materials are immersed in a heated salt solution for quenching. In salt bath quenching, the metal is rapidly cooled by contact with a hot salt solution. The cooling rate of salt bath quenching can be controlled by adjusting the temperature and composition of the salt solution. Increasing the temperature of the salt solution can increase the cooling rate, while adjusting the composition of the salt solution can change the cooling rate within a certain range. Use salt bath media to achieve an even cooling effect. Due to the good thermal conductivity of salt, the metal material can be cooled evenly across the entire surface, reducing deformation and internal stress caused by uneven cooling.
6. Gas: Heat treatment gas medium refers to a heat treatment method that uses inert gases such as nitrogen and argon as the quenching medium. The cooling rate of the heat treatment gas medium is relatively fast. Metal materials can be rapidly cooled by purging an inert gas directly onto the heated metal surface. The speed of cooling can be adjusted by adjusting gas flow and pressure. The gas medium provides an oxygen-free environment and prevents oxidation reactions on the metal surface. Compared with liquid media, the cooling rate of heat treatment gas media is relatively fast, which can reduce the risk of deformation and cracking of metal materials.
