Testing methods for high-strength bolts
Release time:
2020-01-14
The commonly used non-destructive testing methods for high-strength bolts are magnetic particle testing, color testing, and ultrasonic testing. This article focuses on magnetic particle testing. Clean the removed high-strength bolts with solvent, paying special attention to the threads and transition parts during cleaning. Place the high-strength bolt in the longitudinal magnetization coil of the magnetic testing machine. Portable instruments can be used for on-site testing. Longitudinal magnetization is carried out using the wire winding method. Select continuous magnetization and wet method, and carefully investigate the external magnetic marks when spraying magnetic suspension. When the coil passes through low voltage and high current, a longitudinal magnetic field occurs. The high-strength bolt undergoes an induced magnetic field under the effect of a longitudinal coil magnetic field, forming a closed magnetic field in the axial direction of the bolt. If there are cracks that form magnetic leakage, it forms magnetic field leakage. After using magnetic powder, the magnetic mark attracts the magnetic powder to form an enlarged magnetic mark. Magnetic particle testing has a very active induction of cracks on the surface, and the appearance of cracks is intuitive and easy to operate. However, the cleaning workload is too large, which affects the progress of the test. Moreover, the surface has rust and black marks that are difficult to clean. The color contrast between these marks and the magnetic particle is not clear, which affects the investigation of magnetic traces and may lead to leakage. The leakage of magnetic particles adsorbed on the tooth tip of high-strength bolts can also lead to misjudgment.
Clean the removed high-strength bolts with solvent, paying special attention to the threads and transition parts during cleaning. Place the high-strength bolt in the longitudinal magnetization coil of the magnetic testing machine. Portable instruments can be used for on-site testing. Longitudinal magnetization is carried out using the wire winding method.
Select continuous magnetization and wet method, and carefully investigate the external magnetic marks when spraying magnetic suspension. When the coil passes through low voltage and high current, a longitudinal magnetic field occurs. The high-strength bolt undergoes an induced magnetic field under the effect of a longitudinal coil magnetic field, forming a closed magnetic field in the axial direction of the bolt. If there are cracks that form magnetic leakage, it forms magnetic field leakage. After using magnetic powder, the magnetic mark attracts the magnetic powder to form an enlarged magnetic mark.
Magnetic particle testing has a very active induction of cracks on the surface, and the appearance of cracks is intuitive and easy to operate. However, the cleaning workload is too large, which affects the progress of the test. Moreover, the surface has rust and black marks that are difficult to clean. The color contrast between these marks and the magnetic particle is not clear, which affects the investigation of magnetic traces and may lead to leakage. The leakage of magnetic particles adsorbed on the tooth tip of high-strength bolts can also lead to misjudgment.
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