Heat treatment is a kind of equipment used for steel billet induction heating system, steel bar, sucker rod and other metal parts in the metal heat treatment industry. If the heat treatment of the workpiece is not proper, it will lead to the deformation of the metal work piece. What are the specific factors? Let’s get to know each other.
First, the deformation of steel is mainly caused by internal stress or external stress. Internal stress is caused by non-uniform temperature distribution or phase transformation, and residual stress is also one of the reasons. The deformation caused by the external stress is mainly caused by the “collapse” caused by the weight of the workpiece. In special cases, the collision of the heated workpiece or the depression caused by the clamping tool should also be considered. Deformation includes elastic deformation and plastic deformation. The size change is mainly based on the microstructure transformation, so it shows the same expansion and shrinkage. However, when the workpiece has holes or complex shapes, it will lead to additional deformation. If a large amount of martensite is formed by quenching, it will expand, and if a large amount of retained austenite is produced, it will shrink accordingly. In addition, shrinkage usually occurs during tempering, while secondary hardening occurs in alloy steels. If cryogenic treatment is carried out, it will be further expanded due to martensization of retained austenite. The specific volume of these structures increases with the increase of carbon content, so the increase of carbon content also increases the size change.
Second, the main period of occurrence of quenching deformation is
1. Heating process: during the heating process, the workpiece is deformed due to the gradual release of internal stress.
2. Heat preservation process: self-weight collapse deformation, namely collapse bending.
3. Cooling process: deformation due to uneven cooling and microstructure transformation
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Specialist of bar heat treatment furnace in China; Glad to be your business partner in induction heating field.
Post time: 05-08-2019