Failure analysis of internal thread cracks in the drill collar joint of a logging tool while drilling
After operating a logging tool while drilling,it was found that there were cracks in the internal threads of the drill collar joint,causing the tool to be unable to operate;By analyzing the microstructure of the fracture surface,energy spectrum analysis,chemical composition analysis,hardness testing,and metallographic structure analysis,the mechanism of crack formation is comprehensively determined and solutions are proposed.The analysis results indicate that under corrosive environments and complex stress conditions,the internal thread cracks in the joint originate from pits on the tooth top sidewall,and the cracking form is transgranular cleavage fracture,which combines corrosion fatigue fracture and stress corrosion cracking;One of the mechanisms behind crack formation is the increased corrosion sensitivity caused by the presence of numerous precipitates along grain boundaries in the material of drill collars.
while drilling logging tooldrill collarinternal threadcracksfailure analysis
万方数据
维普
