Annealing is a metal heat treatment process that involves slowly heating the metal to a certain temperature, maintaining it for a sufficient time, and then cooling it at an appropriate rate, sometimes by natural cooling, sometimes by a controlled cooling method.
1) To reduce hardness, soften the workpiece, and improve machinability.
2) To improve or eliminate various structural defects and residual stresses caused by steel in the casting, forging, rolling, and welding processes, and to reduce deformation, cracking or cracking tendencies of the workpiece.
30 To refine grain size, improve the structure to enhance the mechanical properties of the workpiece, and eliminate structural defects.
4） To uniformly organize and distribute material components, improve material properties or prepare for future heat treatment, such as annealing and tempering.
In practical production, the application of annealing furnace annealing process is very wide. According to the different purposes of annealing required by the workpieces, there are many annealing heat treatment processes, such as full annealing, spheroidizing annealing, stress-relief annealing, etc.
The annealing furnace series of industrial furnaces are widely used in various industries such as casting, metallurgy, automotive, aerospace, military, shipbuilding, light industry, and electric power. They can be used for different annealing heat treatment processes for various metal workpieces such as high-chromium, high-manganese steel castings, gray iron castings, rolling mill rolls, bearings, steel balls, and wear-resistant linings.
The annealing furnace is manufactured with a square or circular furnace body structure. The furnace is equipped with refractory bricks and alumina silicate fiber composite insulation, or a full fiber insulation furnace lining structure. The workpiece is placed in the furnace, and the furnace is heated by electric heating or fuel such as oil, gas. The workpiece in the furnace is heated to the required annealing process temperature under natural atmosphere or protective atmosphere, maintained for a period of time, and then cooled naturally or at a controlled rate. Due to the wide variety of annealing furnaces, their operating modes also vary. The trolley type annealing furnace has an independent loading and unloading trolley for more convenient loading and unloading operations, and can load large and heavy workpieces. The pit-type annealing furnace is suitable for vertical loading of shafts, rods, pipes, and other workpieces, and is not easily deformed during annealing heating.
1）Annealing furnace can be classified by different heating methods, such as electric heating, fuel heating, and gas heating. And they are respectively electric annealing furnace, oil annealing furnace, and natural gas annealing furnace.
2) Annealing furnace with different furnace body structures are trolley type annealing furnace, pit-type annealing furnace, box-type annealing furnace, and hood-type annealing furnace.
3) Annealing furnace can also be classified into vacuum annealing furnace, controlled atmosphere annealing furnace, and annealing furnace heated in natural atmosphere.