Heat treatment method of seamless steel pipe (eg:ASTM A53): complete annealing and incomplete annealing
The effect of complete annealing
①Refine the grain
②Eliminate Widmanstatten organization and band structure
③Reduce hardness and increase plasticity, which is beneficial to cutting
④Eliminate internal stress
⑤For castings, coarse crystals can be eliminated, and impact toughness, plasticity and strength can be improved
Application and description of complete annealing
①Small and medium-sized castings, forgings and hot-rolled steels used for Asian joint folding steel
②Preparation heat treatment for hypoeutectoid steel
③Cannot be used for hypereutectoid steel, otherwise it will form network carbides and reduce its toughness
④Full annealing is used for large castings and forgings. Due to stre ss, it is easy to cause deformation and cracking, so stress should be eliminated in time
The effect of incomplete annealing
①Reduce hardness, increase plasticity, improve machinability and eliminate internal stress
②Get spherical pearlite
Application and description of incomplete annealing
①Used for hypereutectoid steel without network carbide structure, rarely used for hypoeutectic steel
②Preparation heat treatment for high carbon steel and bearing steel
When there are network carbides in the over-precipitation high carbon steel, normalizing must be used to eliminate them before incomplete annealing
The effect of complete annealing
①Refine the grain
②Eliminate Widmanstatten organization and band structure
③Reduce hardness and increase plasticity, which is beneficial to cutting
④Eliminate internal stress
⑤For castings, coarse crystals can be eliminated, and impact toughness, plasticity and strength can be improved
Application and description of complete annealing
①Small and medium-sized castings, forgings and hot-rolled steels used for Asian joint folding steel
②Preparation heat treatment for hypoeutectoid steel
③Cannot be used for hypereutectoid steel, otherwise it will form network carbides and reduce its toughness
④Full annealing is used for large castings and forgings. Due to stre ss, it is easy to cause deformation and cracking, so stress should be eliminated in time
The effect of incomplete annealing
①Reduce hardness, increase plasticity, improve machinability and eliminate internal stress
②Get spherical pearlite
Application and description of incomplete annealing
①Used for hypereutectoid steel without network carbide structure, rarely used for hypoeutectic steel
②Preparation heat treatment for high carbon steel and bearing steel
When there are network carbides in the over-precipitation high carbon steel, normalizing must be used to eliminate them before incomplete annealing
