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Steel annealing and normalizing

Date锛2013-10-29 9:31:20

1 , annealing:
Annealing and normalizing is the production of very broad application of preliminary heat treatment process, mainly used to improve the cutting performance of the material . For some uneven force , performance-demanding machine parts , also can be used as the final heat treatment .
Isothermal annealing of austenitic steel after rapid cooling to a temperature of isothermal pearlite formation of insulation, so that supercooled austenite into pearlite , cooled to room temperature.
Spheroidizing will hypereutectoid carbon steel is heated to above Ac1 20 ~ 30 ℃, heat 2 ~ 4h, so that does not happen cementite flake off completely dissolved into small chain or punctate , dispersed in the austenite a substrate , in the subsequent slow cooling process , or in fine cementite original point of the core body , or in a carbon-rich austenite region as a new core to form a homogeneous granular cementite
   Homogenization ( diffusion annealing ) of the workpiece is heated to about 1100 ℃ , heat 10 ~ 15h, slow cooling in the furnace to 350 ℃, then cooled baked . Workpiece after homogenization annealing, very coarse austenite grains , must conduct a full annealing or normalizing to grain refinement , eliminating overheating defects.
   Stress relief annealing the workpiece with the furnace heated slowly to 500 ~ 650 ℃, insulation, with the furnace slowly cooled to 200 ℃ baked cooled . Mainly used to eliminate processing stress .
Recrystallization annealing the material is heated to above the recrystallization temperature , slow cooling after heat process method.
    Fully annealed for hypoeutectoid carbon steel and alloy steel castings and forgings ; isothermal annealing for relatively stable austenitic alloy steel ; ball annealing for eutectoid steel , eutectoid steel and alloy tool steel ; uniform annealing for high-quality requirements of quality high alloy steel ingots and steel castings segregation serious ; to stress annealing for castings, forgings , weldments , cold stamping parts and machining parts ; recrystallization annealing mainly used to remove hardening .
2 , normalizing :
   The hypoeutectoid steel heated to above Ac3 30 ~ 50 ℃, eutectoid carbon steel is heated to Accm above 30 ~ 50 ℃, insulation, air cooling method is called normalizing . For carbon steel and in low alloy steel, high alloy austenite as very stable , even in the air will be cooled to obtain martensite. For low carbon steel , low-carbon low-alloy steel , grain refinement , improved hardness (140 ~ 190HBS), improved cutting performance ; For eutectoid steel , eliminating the second network cementite , is conducive to the ball annealing proceed.


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