1 The basic process of heat treatment of metal materials

The heat treatment process can be divided into three categories: overall heat treatment, chemical heat treatment and surface heat treatment. Depending on the heating medium, heating temperature and cooling method, each great beauty can be divided into different heat treatment processes.

1. Overall heat treatment is a metal heat treatment process that heats the entire workpiece and then cools it at a suitable speed to change its overall mechanical properties. 2. The overall hot treatment process of steel is classified into normalizing, annealing, floating fire and interfire. Basic 1. Annealing of steel. Annealing of steel is to heat the steel to a temperature above the critical humidity point Ae1, keep the temperature for a period of time and then slowly cool it down. It is said that a kind of heat treatment process to obtain a structure close to the equilibrium state. Yes: By reducing the degree of steel to change the machinability, it can also eliminate stress and add 1 hardening, resulting in plasticity, which is beneficial to the forming and adding of dry steel. 1. Eliminates the contribution of the steel and enhances the process performance and use performance. It can also refine the grains, change the shape and distribution of carbides, and prepare for post-heat treatment. In other words, the annealing of steel bars is actually a preliminary preparation process for other heat treatment processes. Good process performance and use performance, for the preparation of batch weaving for improving quenching, the quenching or demanding of steel is to heat the steel to A3 or above 30-50℃. After maintaining a certain temperature, it is cooled to room temperature in the air A hot plastic process, the effect of normalizing is similar to annealing, but the resulting structure is finer. Changyang improves the cutting performance of the material, and is sometimes used as the final heat treatment for some parts with high requirements, that is, for ordinary general structures. It can be used as a final heat treatment, and for dry, ammonia-carbon steel, it is used as a kind of pre-heat treatment to obtain suitable hardness from the surface. The floating fire of cutting and processing steel refers to heating the temperature to the critical point. Temperature Ac3 or a certain temperature above Ac1, after holding for a period of time, cooling at a cooling rate greater than the critical cooling rate, the structure of the quenched steel will change, and the steel will become even harder after quenching, but at the same time, The floating fire coolants commonly used in our production and life are: oil, salt water, water, nitrates, etc. The metal parts that we will burn in red in the film and television cuts will be burned into the water, which is the process of steel floating fire. The effect of quenching of steel in F significantly increases the hardness and strength of steel, and the use of the net fire process can obtain different comprehensive mechanical properties, so as to meet the requirements of different workpieces. The tempering of tempered steel refers to the After the floating fire, the steel is heated to a suitable temperature below Ae1 and kept for a period of time, and then cooled to the heat treatment method of poetry. The role of steel tempering is to reduce the brittleness of steel after floating fire, reduce or directly eliminate internal stress, thereby preventing the occurrence of cracking and deformation of steel parts. Tempering is divided into low temperature, medium temperature, and high temperature tempering. Its classification The basis is the difference in temperature during tempering. Low temperature tempering refers to the heating temperature of 150-250 ℃, low temperature tempering is widely used in the manufacture of various molds and bearings. Medium temperature tempering is heating temperature 350-500℃, medium temperature national fire is mainly used in some rigid structural steels and springs, and high temperature tempering means heating temperature reaches 500600℃. It is worth mentioning that people in production The heat treatment process that combines quenching and high-temperature national fire processes is often called word quality treatment. Quenching and tempering treatment is extremely important in the production process of various important mechanical parts, such as parts gears and crank wheels that work under alternating loads.