Cracking Failure Analysis of Drill Pipe Joint with Hardbanding

A batch of drill pipe joints in a well cracked and failed due to hardbanding. In this study, various experiments were conducted to analyze the reasons for cracking failure, including data verification, macroscopic morphology analysis, mechanical properties, microstructure analysis, and micro-Vickers hardness of cracked areas, as well as macroscopic, metallographic, and energy spectrum analysis of the fracture surface after opening the cracked area. The results indicated that (1) the chemical composition, tensile strength, Charpy impact test, and Brinell hardness results of the joint met the requirements of the order technical conditions. (2) The hardbanding in the cracked area had multiple pores and cracks on its outer surface and inside. The maximum diameter of the internal porosity was about 3.4 mm, and the length of the internal crack was about 1 mm. (3) The main reason for the cracking of a batch of drill pipe joints due to hardbanding is a quality problem of the secondary repair welding of the hardbanding. The cracks in the failed drill pipe originated from the porosity and cracks in the hardbanding of the drill pipe box joint. Under the influence of alternating stress and high-pressure mud erosion underground, the cracks rapidly extended to the inner wall, and the porosity in the hardbanding accelerated crack propagation, ultimately causing the drill pipe to crack and fail.