Research on Fatigue Failure of Steel E4330 for Fluid Cylinder

Abstract:

Fluid cylinder as an important fracturing equipment with stable and reliable performance is commonly applied in oil and gas fields, but it fractures frequently and its working life is generally low, which has seriously affected the fracturing process efficiency. In this paper, we used the stereo microscope, scanning electron microscope (SEM), direct reading spectrometer, metallurgical microscope and bending fatigue testing machine to study the fatigue failure mechanism of steel E4330 for fluid cylinder. The fracture analysis, hardness test, metallographic observation, bending fatigue test and pre-corrosion fatigue test were carried out. The result shows that the main cracking form of the fluid cylinder is fatigue cracking, the cleavage crack initiated near the intersection line and extended friable due to the corrosion and impact wear effects from the fracturing fluid and the high stress of the fluid cylinder; the fluid cylinder material E4330 contains a variety of alloy elements, and its organization is the uniform sorbite which can meet the working requirements. It has been observed that the fatigue limit of the material is 607MPa, and at a higher stress, the fatigue life would be nearly halved in the corrosive environment. As the fatigue life would greatly reduce due to the corrosion effects from the fracturing fluid, we should control the working stress and make measures for anti-corrosion.

• Periodical: Materials Science Forum (Volume 814)
• Pages: 241-248
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.814.241
• Online since: March 2015
• Authors: Ben Sheng Huang, Jie Lu
• Keywords: Bending Fatigue Test, Failure Analysis, Fatigue Fracture, Fluid Cylinder, Pre-Corrosion

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