Tempering process of trolley type heat treatment furnace
1. What is tempering? Tempering is to heat the metal material parts after quenching heat treatment to a certain temperature. After a certain time of heat insulation heat preservation, it is a necessary yoga style cold heat treatment processing technology. Tempering is a practical operation after quenching, it is also a process flow before the end of workpiece heat treatment punishment, so as to increase the connection between quenching tempering Technology is called the middle late processing punishment.
2. The key objectives of quenching tempering are as follows: 1) to improve the thermal stress ductility, the quenched parts have very large in-situ stress ductility, if tempered immediately, it will often cause deformation even cracking. 2) Negotiate the physical properties of the workpiece. After quenching, the workpiece has high strength ductility. In order to meet the requirements of various parts, it can go through the tempering process to negotiate the strength, compressive strength, plastic deformation ductility. 3) Stable workpiece specification. The composition of the alloy can be kept stable after tempering, no deformation will occur during the subsequent tempering. 4) Tempering process can improve the machinability of some carbon steels.
3. The contamination of tempering process depends on: (1) the reliability of lifting mechanism makes the workpiece to be modified in the process of performance, so that the geometric specifications characteristics of workpiece can be connected smoothly. ② Cutting off the thermal stress is convenient to improve the performance characteristics of the workpiece stabilize the geometric specifications of the workpiece. ③ Negotiate the physical properties of the steel to meet the performance requirements. Tempering often has this kind of contamination, because the temperature is reduced, the ability of molecular fitness exercise is improved, the molecules of iron, carbon other aluminum alloy elements in steel can quickly stop spreading, the molecules are arranged combined again, so that the unstable imbalance mechanism is gradually modified into a stable equilibrium mechanism. The removal of thermal stress is also related to the decrease of temperature the decrease of compressive strength of metal materials. When the steel is tempered, the strength compressive strength drop, the plastic deformation increases. The higher the tempering temperature, the greater the modification of the physical properties. Some carbon steels with high element composition of aluminum alloy will precipitate some fine metal compounds during limited tempering at a certain temperature, which will increase the compressive strength strength. This kind of scene is called secondary hard bottom. The punishment regulation of hot processing in trolley type heat treatment furnace: the workpiece whose main purpose does meet the requirements shall be tempered at the temperature that does meet the requirements in the performance. ① NC blade, rolling bearing, nitrided quenched parts, inner quenched parts are usually tempered at ultra-low temperature below 250 ℃. After ultra-low temperature tempering, the strength is changed much, the thermal stress is reduced, the ductility is slightly improved. ② High ductility necessary ductility can be obtained by tempering at 350-500 ℃. ③ The parts made of medium carbon alloy structural steel are usually tempered at 500 ~ 600 ℃ at ultra-low temperature, so as to obtain the suitable excellent combination of compressive strength ductility. When steel is tempered at 300 ℃, its ductility is usually high, which is called a kind of tempering ductility. Shallow can be tempered in this temperature range. After ultra-low temperature tempering, some medium carbon alloy tool steels are supposed to cool slowly to room temperature, which is also easy to become brittle. This kind of scenario is called type II tempering ductility. Adding molybdenum in steel cooling in oil water during tempering can prevent the second kind of tempering ductility. This kind of ductility can be removed by reheating the steel with type II tempering ductility to the original tempering temperature. In manufacturing, it is often based on the specification of workpiece characteristics. According to the inconformity of heating temperature, tempering is divided into ultra-low temperature tempering, medium temperature tempering ultra-low temperature tempering. Quenching subsequent ultra-low temperature tempering phase of the heat treatment process known as heat treatment, that is, in addition to high aspect ratio compressive strength, good plastic deformation ductility. 1) Ultra low temperature tempering: 150-250 ℃, m cycles, improve thermal stress ductility, improve plastic ductility, have high strength wear resistance. For the construction of measuring instruments, CNC blades roller bearings. 2) Medium temperature tempering: 350-500 ℃, t-cycle, with high ductility, inevitable plastic deformation strength. It is used to build spring yellow, forging die, etc. 3) Ultra low temperature tempering: 500-650 ℃, s cycle, with excellent comprehensive physical properties. Used to build transmission gear, engine crankshaft, etc.
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