Currently more than water as the heat-treated steel hardening agent, this is because the quenching medium, water is most economic, security, environmental pollution. However, rapid cooling of the water. When hardened steel prone to distortion, seamless severe deformation due to inability to perform the next procedure scrapped. Therefore, the choice of quenching way to reach both to make steel hardening requirements, but also to control the deformation within the allowable range. According to the above analysis, the first pipe is quenched in rotation is ideal, while internal and external cooling. In the cold water is injected into the nozzle tube, water flow rate Efficiency Heating
Cooling
of not less than 10M / s better. External cooling using spray or immersion quenching tank can be, but there must also quench tank agitation nozzle. In short, seamless quench cooling capacity to meet the requirements should be cooled as even as possible, this is the way the election antimony hardened guiding ideology. Hardening agent is preferably a high temperature zone in the cooling rate is faster, in order to avoid decomposition of austenite to enhance the hardenability of the steel in the low temperature region i slower cooling rate to reduce the stress when the martensitic transformation, reducing deformation or cracking. Ideal hardening agent does not exist, but the choice of quenching agent should consider two factors. Select hardening agent according to many factors should be considered varieties of steel, technical conditions and composition of the steel and so on. Oil pipe, for example, high-grade steel (strength) of steel heat treatment is used in quenching process, ie quenching and tempering. Steel multi-use low carbon content of the carbon alloy steel, the effective thickness of seamless steel pipe (wall thickness) are basically the same, the stress distribution throughout the quenching difference is small, causing cracking and relatively low risk of some Therefore, you can use water as a hardening agent priority. Advantages of water is cooling fast. Can improve the hardenability of steel, steel can reduce the alloy content, reduce production costs. Also water as the quenching agent. On safety, the economy. The same situation due to water cooling speed, resulting in a large seamless steel pipe deformation, and there are some imperfections in the surface of the steel pipe, will expand the quenching of defects and scrap. If the carbon content of the steel is high, in order to reduce distortion or cracking, the slower cooling rate should be selected rapidly quenching oil, or water-quenching liquid quenching agent is hardened.
