Heat treatment |
Heating temperature |
Purposes |
Suitable steel |
Scope of application |
Full annealing |
Above Ac3
From 20 to 40℃ |
Refining grains, eliminating internal stress, network and Widmannstatten structures and reducing hardnes |
Hyposteel |
Heat treatment of tube billets and finished pipes |
Partial annealing |
From Ac1 to Ac3
From780 to 800℃
From Ac1 to Acm
From750 to 770℃
|
Improving dispersion of pearlite, eliminating internal stress, preventing decarburization and adopting slow cooling rate can obtain spherical pearlite
|
For hyper-eutectoid steel |
Intermediate heat treatment, finished pipe heat treatment and spheroidizing heat treatment |
Recrystallization annealing |
Ac1
From 600 to 700℃ |
Eliminating internal stress and work hardening, reducing hardness and restoring plasticity
|
All kinds of carbon steel and low alloy steel |
Intermediate heat treatment |
Normalizing |
Above Ac3
From 30 to 50℃ |
Improving the machinability of mild steel and mechanical properties, refining austenite grains and eliminating net carbide
|
Hyposteel |
Finished pipe heat treatment |
Quenching |
|
Eliminating work hardening and internal stress |
|
Intermediate heat treatment and finished pipe heat treatment for stainless steel pipes |
Quenching and high temperature tempering |
Normalizing and high temperature tempering and annealing and tempering |
Eliminating internal stress, improving toughness of the material and obtaining high strength and hardness |
Low alloy structural steel |
Finished pipe heat treatment
|