Fracture Causes and Characteristics of Aluminum Cable Reinforced Conductor Steel in Strain Clamp

To reveal the failure causes and mechanism of the conductor serviced for 18 year in the strain clamp, macroscopic examination, scanning electron microscopy, spectroscopy analysis, mechanical testing and metallographic examination were applied to analyze the characteristics of failed clamp and the fracture morphology and microstructure degradation characteristics of the conductor. It was found that half of the inner wall of strain clamp was seriously compressed, while the other half was covered by thick scaling layer. There were a lot of corrosion pits on the surface of outer layer aluminum strands. The area reductions of aluminum strands and steel cores had an increase of 10%. The fibrous characteristics of the longitudinal metallographic structure weakened at the fractures of failed aluminum strands and steel cores, and even disappeared at the necking of steel cores. The poor compression in the clamp caused the corrosion in the contact surface of the conductor and the clamp, leading to the scaling of corrosion products and dust and the increase of heat produced in the tube. The failure finally occured due to the temperature elevation and material deterioration.