Yield strength is an important concept in the mechanical field of seamless steel pipes, where the stress value of the pipe increases when a material with ductility undergoes yielding. When a seamless steel pipe is subjected to stress, it will deform, which can be divided into: plastic deformation and elastic deformation.
Plastic deformation persists even after the external force is removed, causing seamless steel tubes to deform.
Under external forces, elastic deformation occurs. When the external force is removed, the deformation will also disappear.
Yield strength is the stress value at which seamless steel tubes begin to undergo plastic deformation. However, due to the brittleness of materials, there is no significant plastic deformation when subjected to external force, thus only ductile materials possess yield strength.
The yield strength is the stress at which yielding occurs, resisting minor plastic deformation. When the force exceeds this limit, the part will fail and cannot be restored.
External factors affecting the yield strength of seamless steel pipes include temperature, strain rate, and stress state. As the temperature decreases and the strain rate increases, the yield strength of seamless steel pipes also increases. Particularly in the case of body-centered cubic metals that are sensitive to temperature and strain rate, it is easy for the steel to undergo low-temperature embrittlement. The influence on the stress state is also significant. Although yield strength is an essential indicator reflecting the inherent properties of the manufacturing material, the yield strength varies due to different stress states.
Internal factors affecting yield strength include: bonding, microstructure, structure, and atomic nature. When comparing the yield strength of seamless steel pipes with ceramics and high polymer materials, we can observe that the influence of bonding is a fundamental issue.