Decarburization in the decarburization annealing line is a phenomenon that the surface carbon content of steel decreases when heated. The process of decarbonization is that the carbon in steel reacts with hydrogen or oxygen at high temperatures to form methane or carbon monoxide.

The decarburization of decarburization and annealing lines is harmful. The countermeasures to prevent decarburization mainly include the following aspects:

1) When heating the workpiece of the decarburization and annealing line, reduce the heating temperature and residence time at high temperatures as much as possible; Reasonably selecting the heating speed to shorten the total heating time;

2) Create and control an appropriate heating atmosphere to render it neutral or use protective gas for heating. For this purpose, special heating furnaces can be used (heating in a well deoxidized salt bath furnace has a lower tendency to decarbonize than heating in an ordinary box furnace);

3) During hot pressure processing, if production is interrupted due to some accidental factors, the furnace temperature should be lowered until production resumes. If the pause time is long, the blank should be taken out of the furnace or cooled down with the furnace;

4) When performing cold deformation, minimize the number of intermediate annealing and reduce the temperature of intermediate annealing, or use softening tempering instead of high-temperature annealing. During intermediate annealing or softening tempering, heating should be carried out in a protective medium;

5) When heated at high temperatures, the surface of the steel is protected by coverings and coatings to prevent oxidation and decarburization;

6) Correct operation and increase the machining allowance of the workpiece to completely remove the decarburized layer during machining.

Our company's decarburization and annealing production line for oriented silicon steel has an annual output of 70000-80000 tons. HiB specification thickness 0.18-0.23mm; The specification and thickness of CGO decarburization material are 0.635mm. Part of our decarbonization II rolling stock can be sold directly.

Decarburization annealing line - Decarburization annealing is one of the malleable annealing processes for malleable cast iron. The process of decarburization annealing line is: the white cast iron is heated to a high temperature in an oxidizing medium and maintained for a long time, resulting in decarburization of the surface of the billet and graphitization of the core. The resulting cast iron is called white core malleable cast iron. Decarburization annealing line - Decarburization annealing process curve

Decarburization annealing line - Decarburization annealing requires high heating temperature, long holding time, and uneven distribution of the obtained microstructure along the cross-section. Therefore, in recent years, it has been mostly replaced by the malleable annealing process. [

Decarburization and annealing line - Before annealing, the white cast billet (with pearlite, bainite, and cementite structures) is loaded into a box filled with Fe3O4 and construction sand, or heated to a high temperature (typically 950~1050 ℃) in an oxidizing atmosphere furnace and maintained for a long time. During the heat preservation process, decarburization occurs on the surface, and the free cementite at the core is transformed into graphite. Decarburization and annealing line - After completion of high temperature insulation, the blank is cooled to 650~550 ℃ in the furnace and discharged for air cooling. After such treatment, the surface of the cast iron is ferrite, and the core is pearlite (sometimes with a small amount of ferrite or cementite) and flocculent graphite structure. Due to the poor plasticity of pearlite, the center of the fracture is white when broken, hence the name of white core malleable iron. Decarburization annealing line - After decarburization annealing, the machinability and toughness of the casting are improved.