Closed-Form Solutions for Stress Intensity Factor and Elastic Crack Opening Displacement for Circumferential Through-Wall Cracks in the Interface between an Elbow and a Straight Pipe under Internal Pressure

Jang, Youn-Young; Jeong, Jae-Uk; Huh, Nam‐Su; Kim, Ki-Seok; Cho, Woo-Yeon

doi:10.7735/ksmte.2015.24.5.553

Cited by 3 publications

(3 citation statements)

References 8 publications

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“…It was easy to Figure the pearlite transformation temperature by CCT curves, in fact, this temperature is about 607 ℃ by our previous studies. From the above, it is clear that brittle microstructure pearlite caused by Mn and C segregation was the inner cause of the crack, internal stress of the forging during cooling process was the external cause [6,7]. The key point of quality control lies in decreasing the segregation of Mn and C, meanwhile, the cooling rate after forging should be slowed in order to reduce the internal stress of the forging.…”

Section: Resultsmentioning

confidence: 99%

Common Defect Analysis for Large Section Special Steel Forging

Wen¹,

Gao²,

La³

2017

MSF

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In order to Figure the common defect in large section special steel forging and find the solution, systematic study was carried out on hundreds of large section special steel forgings in a domestic famous steel mill. The steels included: low-carbon steel Q345D/E, medium-carbon steel 27SiMn, high-carbon steel GCr15SiMn, stainless steel 20Cr13. Both the amount and type of all the defect in the above steel were calculated and analyzed. The results showed that the common defects of the steel were slags, inclusions, loose (cavity) and inner cracks. The evolution of the cavity in the ingot during forging process was simulated by a numerical simulation software Deform-3D. The inner cracks in Q345D/E and 27SiMn initiated after A→F+P transformation The cracks in GCr15SiMn formed after the precipitation of net-like proeutectoid carbides. The cracks in 20Cr13 formed after the precipitation of net-like carbides. The internal cause of the cracks was relevant to composition segregation and internal stress in the forging. The external cause was connected with effect of slow cooling. Based on the above study, a set of new process was proposed and put into industrial application, with the result that the qualified ratio of flaw inspection in the above steel mill was improved from 20% to above 87%.

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Section: Resultsmentioning

confidence: 99%

Common Defect Analysis for Large Section Special Steel Forging

Wen¹,

Gao²,

La³

2017

MSF

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“…The K solution for the present problem is taken from Ref. [19] and is summarized for completeness in appendix A. For the present problem, the fully-plastic component of J (i.e.…”

Section: The Reference Stress Methodsmentioning

confidence: 99%

“…Similarly, applications of the reference stress method to the crack problem at the interface between straight pipe and elbow were limited to the case of circumferential through-wall crack [16] and circumferential constant-depth surface crack under in-plane bending [17]. Recently, Jang et al [19,20] reported a completed set of the fracture mechanics parameters of circumferential through-wall crack at the interface between elbow and straight pipe under internal pressure. However, application of the reference stress method to this problem has not been reported.…”

Section: Introductionmentioning

confidence: 99%

Reference Stress Approach for Fracture Assessment of Extrados Circumferential Through-Wall Crack at the Interface between Elbow and Pipe Subjected to Internal Pressure

Kasivitamnuay

Singhatanadgid

2018

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The fracture assessment of a cracked component can provide technical support for an effective maintenance and a prevention of catastrophic accident. The present study applies the reference stress method to extend the J-integral solution from the finite element analysis for the Ramberg-Osgood stress-strain relationship to other types of stress-strain relationship. The problem in this study is an extrados circumferential through-wall crack at the interface between elbow and pipe subjected to internal pressure. The finite element results from the literature were analyzed to determine the optimized reference pressure. The fracture loads predicted by the reference-stress-based failure assessment curve which incorporated with the optimized reference pressure were compared with those predicted by the finite-element-based failure assessment curve. The failure load predicted from the reference-stress-based failure assessment curve deviated from that predicted from the finiteelement-based failure assessment curve within the range of-7% to 11%.

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