مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی تجربی رفتار خستگی و تخمین نمودار تنش- عمر فولاد ایکس شصت و پنج

نوع مقاله : پژوهشی اصیل

نویسندگان
دانشگاه بیرجند
چکیده
فولادهای ترمومکانیکال به دلیل چقرمگی و مقامت بالا در برابر رشد ترک، به طور گسترده در خطوط انتقال نفت و گاز استفاده می­شوند. بخش وسیعی از خطوط لوله فولادی به کار رفته در صنعت نفت و گاز جمهوری اسلامی ایران از جنس فولاد API X65 است. نوسان فشار داخلی گاز در لولههای فولادی میتواند باعث شکست خستگی و انفجار شود. به همین دلیل، بررسی آسیب و یکپارچگی سازه­ای این لولهها از اهمیت بالایی برخوردار است. در این تحقیق منحنی تنش- عمر و استحکام خستگی فلز پایه لوله فولادی API X65، با انجام آزمایش خستگی تخمین زده شده است. به این منظور، تعداد 24 و 25 نمونه آزمایشگاهی به ترتیب در راستای درز جوش (جهت طولی یا غلتککاری) و عمود بر درز جوش (جهت عرضی کلاف اولیه) طبق استاندارد، از لوله در مقیاس صنعتی با قطر خارجی 1219 میلیمتر و ضخامت 3/14 میلیمتر تهیه شد. نمونههای تهیه شده تحت آزمایش خستگی خمشی- چرخشی کاملا معکوس شونده قرار گرفت و با در نظر گرفتن توزیع نرمال لگاریتمی، تحلیل آماری نتایج انجام شد. منحنی میانگین، منحنی مشخصه و بازه اطمینان نتایج آزمایش در ناحیههای عمر خستگی محدود و استحکام خستگی براساس استانداردهای ISO 12107 و ASTM-E739 به دست آمد. مقدار میانگین حد دوام فلز پایه در راستای درز جوش و عمود بر درز جوش به ترتیب برابر 291 و 305 مگاپاسکال به دست آمد. این مقادیر به خوبی در محدوده پیشبینی 4/0 تا 6/0 استحکام نهایی فولاد آزمایش شده و بالاتر از حد دوام فلز جوش (258 مگاپاسکال) این لوله قرار دارد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Experimental Investigation of Fatigue Behavior and Assessment of Stress-Life Curve of API X65 Steel

نویسندگان English

Mohammad Tavid
Sayyed Hashemi
University of Birjand
چکیده English

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).

کلیدواژه‌ها English

endurance limit
S-N curve
Fatigue Fracture
gas pipeline
API X65 steel
[1] Alhussein A, Capelle J, Gilgert J, Tidu A, Hariri S, Azari Z. Static, dynamic and fatigue characteristics of the pipeline API 5L X52 steel after sandblasting. Engineering Failure Analysis. 2013;27:1-15.
[2] Slifka AJ, Drexler ES, Nanninga NE, Levy YS, McColskey JD, Amaro RL, Stevenson AE. Fatigue crack growth of two pipeline steels in a pressurized hydrogen environment. Corrosion Science. 2014;78:313-321.
[3] Bandara CS, Siriwardane SC, Dissanayake UI, Dissanayake R. Developing a full range S–N curve and estimating cumulative fatigue damage of steel elements. Computational Materials Science. 2015;96:96-101.
[4] Herrera DA, Albiter A, Cuamatzi-Meléndez R, Terán G, Ochoa-Ruiz G. Fracture-Toughness and Fatigue Crack Growth Evaluation in the Transversal Direction of the Longitudinal Weld of an API X52 Steel Pipeline. Journal of Testing and Evaluation. 2018;46(5):2110-2120.
[5] Mohtadi-Bonab MA, Eskandarib M, Sanayeic M, Dasd S. Microstructural Aspects of Intergranular and Transgranular Crack Propagation in an API X65 Steel Pipeline Related To Fatigue Failure. Engineering Failure Analysis. 2018;94:214-225.
[6] Nguyen TT, Heo HM, Park J, Nahm SH, Beak UB. Fracture Properties and Fatigue Life Assessment of API X70 Pipeline Steel Under the Effect of an Environment Containing Hydrogen. Journal of Mechanical Science and Technology. 2021;4(35):1445-1455.
[7] Farhad Fh, Smyth-Boyle D, Zhang X. Fatigue of X65 Steel in the Sour Corrosive Environment—A Novel Experimentation and Analysis Method for Predicting Fatigue Crack Initiation Life From Corrosion Pits. Fatigue & Fracture of Engineering Materials & Structures. 2021;44(5):1195-1208.
[8] Tavid M, Hashemi SH. Endurance Limit Determination of Weld Metal of API X65 Gas Pipeline Steel. Modares Mechanical Engineering. 2022;23(01):33-44. [In Persian]
[9] Hashemi SH, Mohammadyani D. Characterisation of Weldment Hardness, Impact Energy and Microstructure IN API X65 Steel. International Journal of Pressure Vessels and Piping. 2012;98:8-15.
[10] Hashemi SH, Kimiyabakhsh M. Experimental and Numerical Determination of Fracture Toughness in Gas Pipeline Steel of Grade API X65. Amirkabir Journal of Science & Research. 2013;45(2):1-9. [In Persian]
[11] Specification for Line Pipe, API Specification 5L, 45th Edition. USA: American Petroleum Institute; 2013.
[12] Hashemi SH. Strength–Hardness Statistical Correlation in API X65 Steel. Materials Science and Engineering A. 2011;528:1648-1655.
[13] Farrahi A, Hashemi SH. Experimental Evaluation of Fracture Toughness in Spiral Seam Weld of Thermo-Mechanical Steel. Journal of Solid and Fluid Mechanics. 2012;2(4):25-35. [In Persian]
[14] Metallic Materials—Rotating Bar Bending Fatigue Testing. Switzerland: International Organization for Standardization (ISO); 2010.
[15] Geometrical Product Specifications (GPS)- Surface texture: Profile method- Terms, Definitions and Surface Texture Parameters. Switzerland: International Organization for Standardization (ISO); 1997.
[16] Barbosa JF, Correia JA, Júnior RF, Zhu SP, Jesus AMD. Probabilistic S-N Fields Based on Statistical Distributions Applied to Metallic and Composite Materials: State of the Art. Advances in Mechanical Engineering. 2019;11(8):1-22.
[17] Gope PC. Determination of Minimum Number of Specimens in S-N Testing. Journal of Engineering Materials and Technology. 2002;124(4):421-427.
[18] Metallic materials — Fatigue testing — Statistical Planning and Analysis of Data. Switzerland: International Organization for Standardization (ISO); 2003.
[19]Strzelecki P, Sempruch J, Tomaszewski T. Analysis of Selected Mathematical Models of High-Cycle S-N Characteristics. Technical Sciences. 2017;20(3):227-240.
[20] Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data. West Conshohocken, United States: ASTM International; 2015.
[21] Bassoli E, Denti L, Comin A, Sola A, Tognoli E. Fatigue Behavior of As-Built L-PBF A357.0 Parts. Metals. 2018;8(8):634-647.
[22] Pilkey WD. Peterson's Stress Concentration Factors. 2nd Edition. Canada: John Wiley & Sons, Inc.; 1997.
[23] Budynas RG, Nisbett JK. Fatigue Failure Resulting from Variable Loading. In: Lange M, editor. Shigley’s Mechanical Engineering Design. 9th Edition. New York, USA: McGraw-Hill; 2011. p. 273-295.
[24] Farhad F, Zhang X, Smyth-Boyle D. Fatigue Behaviour of Corrosion Pits in X65 Steel Pipelines. Journal of Mechanical Engineering Science. 2019;233(5):1771-1782.
[25] Hong SW, Koo JM, Seok CS, Kim JW, Kim JH, Hong SK. Fatigue Life Prediction For an API 5L X42 Natural Gas Pipeline. Engineering Failure Analysis. 2015;56:396-402.
[26] Hanafi ZH, Jamaludin N, Abdullah S, Yusof MF, Zain MS. Acoustic Emission Study of Corrosion Fatigue and Fatigue for API 5L X70 Gas Pipeline Steel. Applied Mechanics and Materials. 2012;138-139:635-639.
[27] Zhao ZP, Qiao GY, Tang L, Zhu HW, Liao B, Xiao FR. Fatigue Properties of X80 Pipeline Steels With Ferrite/Bainite Dual-Phase Microstructure. Materials Science & Engineering A. 2016;657:96-103.