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The type of high-frequency annealing process and the role of annealing

Types of high frequency annealing processes and effects of annealing

In the high-frequency quenching process, annealing to the machine is an indispensable process. In it, high-frequency annealing is used. Have we ever seen the real high-frequency annealing process? Do we understand high? What are the types of frequency annealing processes?

1. What is annealing?
Haituo Electromechanical pointed out that annealing is a kind of metal material heat treatment process, which refers to slowly heating the metal material to a certain temperature, maintaining the time, and then cooling at a suitable speed. The role is to reduce hardness, improve machinability; remove residual stress, stabilize the size,

Reduce the tendency of deformation and cracks; further refine the grain size, adjust the structure, and eliminate tissue defects. Accurately, annealing is a heat treatment process for raw materials, including metallic materials and non-metallic materials. Moreover, the annealing of new materials is also different from the annealing of traditional metal materials.

High frequency annealing

2, high-frequency annealing process types
1, fully annealed
It is used to further refine the coarse superheated structure of medium and low carbon steel which has poor mechanical properties after casting, forging and welding. Heating the workpiece to a temperature above 30 to 50 ° C above the temperature at which all of the ferrite is transformed into austenite, and then holding it for a while, then cooling slowly with the furnace, after cooling

Once the austenite changes again, the microstructure of the steel can be thinned.
It is used to reduce the high hardness of tool steel and bearing steel after forging. The workpiece is heated to a temperature of 20 to 40 ° C above the temperature at which the steel begins to form austenite, and is slowly cooled after the heat preservation. During the cooling process, the lamellar cementite in the pearlite becomes spherical, thereby lowering the hardness.
3. Isothermal annealing
It is used to reduce the high hardness of certain alloy structural steels with high nickel and chromium content for cutting. Generally, it is cooled to the most unstable temperature of austenite at a relatively rapid rate, and the austenite is transformed into torsite or sorbite at a suitable temperature for a suitable period of time, and the hardness can be lowered.
4. Recrystallization annealing
It is used to remove the hardening phenomenon (hardness increase and plasticity decrease) of metal wires and sheets during cold drawing and cold rolling. The heating temperature is generally 50 to 150 ° C below the temperature at which the steel begins to form austenite. Only in this way can the work hardening effect be removed to soften the metal material.
5. Graphitization annealing
It is used to make cast iron containing a large amount of cementite into a malleable cast iron with good plasticity. The processing operation is to heat the casting to about 950 ° C, and after proper cooling for a certain period of time, the cementite is decomposed to form a group of flocculent graphite.
6. Diffusion annealing
It is used to homogenize the chemical composition of alloy castings and improve their performance. The method is to heat the casting to the highest possible temperature without melting, and to keep the steel for a long time, and the various elements in the alloy tend to be uniformly distributed and then slowly cooled.
7, stress relief annealing
Used to eliminate the internal stress of steel castings and welded parts. For the steel products to be heated after the formation of austenite temperature below 100 ~ 200 ° C, after cooling in air, can eliminate internal stress

The type of high-frequency annealing process and the role of annealing

3. The role of annealing
Haituo Electromechanical believes that the role of annealing includes:
(1) Reducing the hardness of steel and improving plasticity, which is conducive to machining and cold deformation processing;
(2) The chemical composition and structure of the uniform steel, further refine the grain size, improve the performance index of the steel or prepare the structure for quenching;
(3) Eliminate internal stress and work hardening to prevent deformation and cracking. Annealing and normalizing are mainly used for preliminary heat treatment. For parts with low force and low performance requirements, annealing and normalizing can also be used as the final heat treatment.
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