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采用宏观形貌分析、断口形貌分析、显微组织观察、硬度测试等手段,对伸缩油缸通油管总成的断裂原因进行分析。结果表明,通油管总成的断裂类型为宏观脆性断裂,裂纹源位于活油管焊趾处的熔合线上,管壁一周焊趾处都产生了裂纹并向内壁扩展形成断口的放射区,最后断裂区在内壁形成剪切唇。引起断裂的主要原因是活油管表面的镀铬层残留在熔合线上,裂纹源从镀铬层界面起裂,最后导致活油管在焊接处断裂。
The causes of fracture of telescopic cylinder oil pipe assembly were analyzed by macroscopic morphology analysis, fracture surface morphology analysis, microstructure observation and hardness test. The results show that the fracture type of the oil pipe assembly is macro-brittle fracture. The source of the crack is located on the weld line of the live oil pipe. Cracks occur at weld toe of the pipe wall and extend to the inner wall to form the fracture radiation zone. Finally, the fracture Area in the inner wall shear lip. The main reason for the fracture is that the chrome layer on the surface of the live oil pipe remains on the weld line, the source of the crack starts to crack from the chrome layer interface, and finally the live oil pipe breaks on the weld.