Volume 24, Issue 5 (May 2024)
Modares Mechanical Engineering 2024, 24(5): 317-327 |
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Tavid M, Hashemi S. Experimental Investigation of Fatigue Behavior and Assessment of Stress-Life Curve of API X65 Steel. Modares Mechanical Engineering 2024; 24 (5) :317-327
URL: http://mme.modares.ac.ir/article-15-74776-en.html
URL: http://mme.modares.ac.ir/article-15-74776-en.html
1- University of Birjand
2- University of Birjand ,shhashemi@birjand.ac.ir
2- University of Birjand ,
Abstract: (282 Views)
Thermomechanical steels are widely used in oil and gas pipelines due to their high toughness and high resitance against crak growth. A large part of the steel pipelines used in the oil and gas industry in Iran is made of API X65 steel. The fluctuations of internal gas pressure in steel pipes can cause fatigue failure and lead to gas leakage and explosion. So, the control of damage initiation and structural integrity of gas pipelines is of great importance. In this study, the S-N curve and the fatigue strength of the base metal of the API X65 steel were estimated by performing fatigue tests. For this purpose, 24 and 25 test specimens along the seam weld in the coil transverse direction, and perpendicular to the seam weld along the coil rolling direction were prepared according to ISO 1143 standard, respectively. All test samples were cut from an spirally welded pipe with 1219mm outside diameter and 14.3mm wall thickness and were tested on a completely reverse rotating-bending fatigue machine. Statistical analysis of the results was performed by considering the normal logarithmic distribution. The mean curve, characteristic curve, and confidence interval of the results were obtained both in the finite fatigue life range and in the fatigue resistance. The mean endurance limit of the base metal perpendicular to and parallel to the seam seam were 305 and 291 MPa, respectively which were in the range of 0.4 to 0.6 of material tensile strength and above the seam weld endurance limit (258 MPa).
Article Type: Original Research |
Subject:
Damage Mechanics
Received: 2024/04/21 | Accepted: 2024/08/18 | Published: 2024/04/29
Received: 2024/04/21 | Accepted: 2024/08/18 | Published: 2024/04/29
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