Abstract
This article lists three typical abnormal microstructures of overhead power line suspension clamps, including inclusion, flake graphite and cementite network. A series of tests including macro check, hardness measurement, composition tests, Energy-dispersive x-ray analysis and metallographic observation have been carried out. The experimental results showed that the causes of abnormal microstructures mainly include: high content of impurities, flake graphite blank and unfulfilled annealing heat treatment. It is suggested to strengthen the supervision on suspension clamps before using, and focus on the quality inspection of metallographic structure and composition.
Highlights
In the overhead power line, the suspension clamps is generally used to fix the conductor on the insulator string or to hang the overhead ground wire on the tangent tower
Because the safety factor selected in the line design of overhang wire clip is relatively large, the material used for overhang wire clip is low-end, size accuracy requirements are not high, coupled with the low price, so, extensive production and management are widely used for suspension clamps, and quality supervision mainly depends on the consciousness of suppliers
Content will lead to the occurrence of chain sulfide inclusion; incomplete annealing of white cast iron blank will lead to the distribution of flake graphite among matrix crystals; and annealing temperature, holding time and cooling rate will affect the precipitation of cementite
Summary
In the overhead power line, the suspension clamps is generally used to fix the conductor on the insulator string or to hang the overhead ground wire on the tangent tower. Overhang wire clamp is one of the most widely used products in overhead power lines. Because the safety factor selected in the line design of overhang wire clip is relatively large, the material used for overhang wire clip is low-end, size accuracy requirements are not high, coupled with the low price, so, extensive production and management are widely used for suspension clamps, and quality supervision mainly depends on the consciousness of suppliers. The causes of this three metallographic microstructure anomalies are analyzed in combination with failure analysis cases, and relevant measures are proposed from the perspective of metal technical supervision
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