Two Reasons Can Cause Seamless Steel Pipe Cracking
Seamless steel pipe manufacturers, in the cold drawn seamless steel pipe production process, there is cold hardening and hydrogen embrittlement phenomenon, they are caused by cold drawn seamless steel pipe cracking the main reason, the following mainly on these two specific analysis.
First of all to understand the phenomenon of burst analysis. Cold drawn seamless steel pipe is a smaller diameter of the seamless steel pipe through the drawing die for cold forming cold forming process, the process steps are generally annealing, pickling, drawing. Cold-drawn small diameter seamless steel pipe in the drawing process, sometimes from beginning to end like the same as the cracker bamboo crack phenomenon, and this phenomenon is called a unified crack.
1. Work hardening. Seamless steel pipe in the cold drawn when a large number of plastic deformation, causing significant lattice distortion, so that the lattice energy, metal internal energy increases, resulting in uneven internal stress within the metal, resulting in residual internal stress. This increases the hardness of the metal and decreases the toughness. The higher the metal hardness, the greater the residual internal stress during cold drawing, the more obvious the work hardening phenomenon. When the residual stress reaches a certain value, the metal will be along a row of grain interface tear, the formation of seamless steel pipe cracking.
2. Hydrogen embrittlement phenomenon. In the process of descaling with acid, sulfuric acid and iron react to precipitate hydrogen. Hydrogen in the form of atoms or ions into the steel, the formation of solid solution, hydrogen on the mechanical properties of steel is typical of the performance of hydrogen embrittlement.