对此问题的解释
The development of modern screw steel has created more possibilities for material processing and widening the application of mechanical products in different industries. However, in some cases, the threaded steel may still appear to be of poor quality due to its cold bended performance, such as the appearance of transverse cracks at the root when being subjected to cold bending.
In order to explain the possible causes of transverse cracking in the threaded steel under cold bending performance finish inspection, it is necessary to take into consideration various factors including the cold temperature, the inherent characteristics of the material and the imposed mechanical stress.
First of all, defects of cold temperature are the common cause for metallurgical impurities and cracks. This is due to the fact that when the metal is at its coldest temperature, any impurities that are embedded in the metal such as non-metallic inclusions or segregation of metal may become embrittled and crystallize, thus forming cracks or cleavage planes. In addition, when thread steel is subjected to cold bending, temperature stresses caused by residual strain and torsional shearing forces will act on the steel and cause friction between the metal atoms. This friction enhances the embrittlement on the steel and will lead to cracks if it is too great.
Second, the mechanical property of the threaded steel can also have an effect on its cold bend performance. Generally, during the process of rolling and forming of the thread steel, the mechanical properties of the material would be affected by the high temperature of rolling and forming process, as well as the external pressure and shear applied. If the thread steel contains a high level of carbon, it could become more prone to brittle, due to its low ductility. In the presence of strong mechanical stress imposed during cold bending, this brittle characteristic will be intensified and the material will be more prone to cracking.
Finally, the inherent characteristics of the threaded steel should be taken into account. For example, when the grain size of the threaded steel is too small, fatigue cracking could occur due to the fact that the accumulative strain produced during cold bending could be too great for the material to withstand, leading to transverse cracks. Similarly, if the carbon content is greater than 0.4%, the steel will become more brittle, resulting in higher apparent hardness and increased sensitivity to cracking.
In conclusion, transverse cracking in threaded steel during cold bending performance finish inspection could be caused by various factors such as the cold temperature, the inherent characteristics of the steel and the mechanical stress imposed during cold bending. It is important to pay close attention and assess the influence of all these factors in order to avoid such incidents in the future.
