1. Beryllium oxide: beryllium oxide not only lose a lot of steel, and reduce the surface quality and the forging die forging the service life, if pressed into the metal internal, can cause forgings scrap. Don't remove beryllium oxide can affect car processing.
2. The decarburization: refers to the surface of steel decarburization carbon all or part of the burned off phenomenon. To make the work surface appear decarburization soft point, reduce the surface hardness, wear resistance and fatigue strength.
3. Overheating and burning: overheating refers to more than allowed in steel heating temperature after, grain size in the long bulky. Overheating against heat treatment, make steel become CuiHe mechanical properties is reduced, but can be by forging is fire or after annealing to eliminate. Burning to because the heating time is too long, high temperature, the metal oxide or partial melting appear the phenomenon. A burning, beyond repair.
4. Appear stress: because of the metal inside and outside is heated have difference, the expansion unevenness, produce the stress, says thermal stress. Heating cause microstructure examination has also causes stress changes, says the organization stress. This will make the cracks in the heating, cause car processing workpieces crack and scrap.
5. Cross-sectional appear fracture: the destruction of the defects of steel chemical composition and microstructure uniformity, make the quenching hardness is reduced, mechanical performance go bad. If the annealing temperature is too high when caused by graphite section, will not easy cutting processing and hardened overheating and deformation. But if owe hot or when the annealing temperature is low, it failed to finish pearlite globalization, also go against cutting and later heat treatment.
6. Hard and brittle network carbide: it weakened the adhesion strength of the crystal between material, the mechanical performance significantly worse, especially to help reduce impact toughness, but can be through the fire is to improve or eliminate. If appear ribbon carbide, can make the quenching and tempering the hardness and uneven after organization, and easily deformation, this is also the ferrite pearlite and machining deformation along the direction of the organization a ribbon appears defects. At the same time, it can also reduce steel plasticity and toughness, made the car dimensions is not stable, cutting tool rapid wear.




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