A study on fatigue life evaluation of 42CrMo steel under cyclic loading based on metal magnetic memory method

Abstract

Accidents involving drilling tool fractures in the process of oil and gas resource exploration and development occur frequently, and there are few detection methods for detecting the residual fatigue life of drilling tool joints with irregular surfaces. Therefore, developing a quick and effective method to evaluate fatigue damage in drilling tool joints is particularly important. In this study, a fatigue life evaluation method for ferromagnetic materials was established based on metal magnetic memory (MMM) detection technology, which can be used in the petroleum industry to evaluate the remaining life of drilling tool joints. First, the relationship between the impact load and specimen fatigue life was determined through a simulation, followed by a fatigue test, and the magnetic signals on the surface of the specimen under different fatigue loads were collected. The effects of the three evaluation methods were compared, and it was found that dynamic time warping (DTW) was more accurate for the evaluation of metal fatigue. Finally, a fatigue damage evaluation model for ferromagnetic metallic materials was established, and the feasibility of the method was verified using test data. This method can effectively predict the remaining fatigue life of threaded specimens, and can be applied in the petroleum industry to evaluate the remaining fatigue life of drilling tool joints. This study provides guidance for the petroleum industry in ensuring the safety of drilling tools.