Its chemical composition CSiMnPSPb? 12 15≤0.09≤0. 100.75- 1.050.04-0.090.26-0.35。
Similarly, the national standard of Y 15 is GB/T? 873 1- 1988 Free-cutting structural steel is used to manufacture generally unimportant standard parts, such as bolts, nuts, pipe fittings and spring seats. The c content of Y 15 is slightly higher, and its strength is slightly higher than that of 12 15.
Extended data:
Characteristics of low carbon steel;
1, the annealed structure of low carbon steel is ferrite and a little pearlite, which has low strength and hardness and good plasticity and toughness. Therefore, it has good cold formability and can be cold formed by crimping, bending and stamping. This kind of steel has good weldability. Low carbon steel with low carbon content has low hardness and poor machinability, and normalizing treatment can improve its machinability.
2. Low carbon steel has a great aging tendency, including quenching aging tendency and deformation aging tendency. When steel is rapidly cooled from high temperature, carbon and nitrogen in ferrite are in supersaturated state, and iron, carbon and nitrogen can be slowly formed at room temperature, so the strength and hardness of steel are improved, while plasticity and toughness are reduced. This phenomenon is called quenching aging.
3. Low carbon steel will age even if it is not quenched or air cooled. A large number of dislocations occur after deformation of low carbon steel, and carbon and nitrogen atoms in ferrite interact with the dislocations elastically, and the carbon and nitrogen atoms gather around the dislocation line. This combination of carbon and nitrogen atoms and dislocation lines is called cottrell air mass. It will increase the strength and hardness of steel and reduce the plasticity and toughness, which is called deformation aging.
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