In the production process of astm a179 cold drawn seamless pipe, there are cold hardening and hydrogen embrittlement phenomenon, which are caused by cold drawn seamless tube cracking the main reason.
Analysis of the phenomenon of bursting astm a179 cold drawn seamless pipe is a smaller diameter of the seamless steel pipe through the drawing die for cold forming cold forming, the process route is generally annealing, pickling, drawing. Cold-drawn small diameter seamless carbon steel pipe in the drawing process, sometimes from beginning to end like the same as the cracker bamboo crack phenomenon, we call this phenomenon is cracking.
The reasons for cracking are:
Effect of work hardening, the carbon steel pipe produces a large amount of plastic deformation during cold drawing, causing significant lattice distortion, which increases the lattice energy and increases the internal energy of the metal, resulting in uneven internal stress of the metal and residual residual stress. This will increase the metal hardness, toughness decreased. 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 tear along a certain grain interface, the formation of steel pipe cracking.
The effect of hydrogen embrittlement, in the process of descaling with acid, sulfuric acid and iron react to precipitate hydrogen. Hydrogen penetrates into the steel in the form of atoms or ions to form a solid solution. The effect of hydrogen on the mechanical properties of steel is typical of hydrogen embrittlement.
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