کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7171794 1463748 2016 34 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Surface versus internal fatigue crack initiation in steel: Influence of mean stress
ترجمه فارسی عنوان
سطح در مقابل شروع خستگی داخلی در فولاد: تاثیر استرس متوسط
کلمات کلیدی
استرس متوسط، کرک داخلی، فولاد، عیوب، ماهی چشم،
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی مکانیک
چکیده انگلیسی
Stress-controlled fatigue tests were run at different R ratios (=σmin/σmax) up to at most 3 million cycles on a 2.5%Cr-1%Mo steel (ASTM A182 F22) used in riser tubes connectors for offshore oil drilling. The fatigue lives, as well as the slope of the S-N curves were found to decrease with increasing R and the endurance limit to follow Gerber's parabola. Surface crack initiation without any defect involved, was most often observed for R = −1, −0.5 and 0, while an R ratio of 0.25 triggered crack initiation from either surface or internal pores or chemically inhomogeneous areas, leading, in the latter case, to fish-eye patterns for relatively low numbers of cycles. A further increase in R ratio to 0.5 promoted only defect-initiated surface cracks, while no fatigue fracture was observed within 10 million cycles above R=0.6. These transitions in crack initiation mode are discussed based on X-ray diffraction analyses of residual stresses, elastic-plastic F.E. computations on a unit cell model containing a pore and some fracture mechanics analyses, with a particular attention to environmental effects.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Fatigue - Volume 82, Part 3, January 2016, Pages 437-448
نویسندگان
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