• Title/Summary/Keyword: Austenitic Stainless Steel (316) Piping

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Feasibility Analysis of Simulation on the Mechanical Properties of Neutron Irradiated Austenitic Stainless Steels by Cold-working (냉간가공을 통한 중성자조사된 오스테나이트 스테인리스강의 기계적물성 모사 타당성 분석)

  • Kim, Jin Weon;Kim, Yun Jae
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.15 no.2
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    • pp.9-18
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    • 2019
  • The objective of this study is to investigate the feasibility of simulating the mechanical properties of irradiatied austenitic stainless steels by cold-working. In this study, the tensile properties, cyclic hardening behaviors and fracture toughness of cold-worked TP316L stainless steel were compared with those of austenitic stainless steels irradiated by neutrons. It showed that cold-working can properly simulate the increase in strength and the decrease in ductility and fracture resistance of austenitic stainless steels by neutron irradiation, even though it could not perfectly simulate the microstructures of irradiated austenitic stainless steels. Also, cold-working can appropriately simulate the hardening behaviors of neutron irradiated austenitic stainless steels under monotonic and cyclic loading conditions.

Investigation of Residual Stress Distributions of Induction Heating Bended Austenitic Stainless Steel (316 Series) Piping (유도 가열 굽힘된 316 계열 오스테나이트 스테인리스 강 배관의 잔류응력 분포 고찰)

  • Kim, Jong Sung;Kim, Kyoung Soo;Oh, Young Jin;Chang, Hyun Young;Park, Heung Bae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.809-815
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    • 2014
  • The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects.

Evaluation of Mechanical Properties and Microstructure of Thermally Aged 308 and 316L Stainless Steel Welds (가속 열시효에 따른 308 및 316L 스테인리스강 용접부의 기계적 물성 및 미세구조 평가)

  • Kong, Byeong Seo;Hong, Sunghoon;Jang, Changheui;Kim, Maan-Won
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.13 no.1
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    • pp.92-100
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    • 2017
  • Due to the presence of ferrite phase in the finished welds, austenitic stainless steel welds (ASSWs) are considered susceptible to the thermal aging embrittlement during long-term service in light water reactor environment. In this study, the thermal aging embrittlement of typical ASSWs, E308 and ER316L welds, were evaluated after the long-term exposure up to 20,000 h at $400^{\circ}C$, which is considered as an accelerated thermal aging condition. After thermal aging, the decrease of tensile ductility and fracture toughness was observed. The microstructure observation with high resolution transmission electron microscopy revealed that spinodal decomposition in ferrite phase of both E308 and ER316L welds would be the main cause of the degradation of mechanical properties. Also, it was shown that the difference of thermal ageing embrittlement between ER316L and E308 welds was significant, such that the reduction of fracture resistance for ER316L weld was much larger than that of E308 weld.

Simulating Nuetron Irradiation Effect on Cyclic Deformation and Failure Behaviors using Cold-worked TP304 Stainless Steel Base and Weld Metals (냉간가공된 TP304 스테인리스강 모재와 용접재를 이용한 반복 변형 및 손상 거동에 미치는 중성자조사 영향 모사)

  • Kim, Sang Eun;Kim, Jin Weon
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.16 no.2
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    • pp.58-67
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    • 2020
  • This study presents cyclic stress-strain and tensile test results at room temperature (RT) and 316℃ using cold-worked TP304 stainless steel base and weld metals. By comparing the cyclic hardening/softening behavior and failure cycle of cold-worked materials with those of irradiated austenitic stainless steels, the feasibility of simulating the irradiation effect on cyclic deformation and failure behaviors of TP304 stainless steel base and weld metals was investigated. It was found that, in the absence of strain-induced martensite trasformation, cold-working could properly simulate the change in cyclic hardening/softening behavior of TP304 stainless steel base and weld metals due to neutron irradiation. It was also recognized that cold-working could adequately simulate the reduction in failure cycles of TP304 stainless steel base and weld metals due to neutron irradition in the low-cycle fatigue region.

A review of chloride induced stress corrosion cracking characterization in austenitic stainless steels using acoustic emission technique

  • Suresh Nuthalapati;K.E. Kee;Srinivasa Rao Pedapati;Khairulazhar Jumbri
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.688-706
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    • 2024
  • Austenitic stainless steels (ASS) are extensively employed in various sectors such as nuclear, power, petrochemical, oil and gas because of their excellent structural strength and resistance to corrosion. SS304 and SS316 are the predominant choices for piping, pressure vessels, heat exchangers, nuclear reactor core components and support structures, but they are susceptible to stress corrosion cracking (SCC) in chloride-rich environments. Over the course of several decades, extensive research efforts have been directed towards evaluating SCC using diverse methodologies and models, albeit some uncertainties persist regarding the precise progression of cracks. This review paper focuses on the application of Acoustic Emission Technique (AET) for assessing SCC damage mechanism by monitoring the dynamic acoustic emissions or inelastic stress waves generated during the initiation and propagation of cracks. AET serves as a valuable non-destructive technique (NDT) for in-service evaluation of the structural integrity within operational conditions and early detection of critical flaws. By leveraging the time domain and time-frequency domain techniques, various Acoustic Emission (AE) parameters can be characterized and correlated with the multi-stage crack damage phenomena. Further theories of the SCC mechanisms are elucidated, with a focus on both the dissolution-based and cleavage-based damage models. Through the comprehensive insights provided here, this review stands to contribute to an enhanced understanding of SCC damage in stainless steels and the potential AET application in nuclear industry.

Tensile and impact toughness properties of various regions of dissimilar joints of nuclear grade steels

  • Karthick, K.;Malarvizhi, S.;Balasubramanian, V.;Krishnan, S.A.;Sasikala, G.;Albert, Shaju K.
    • Nuclear Engineering and Technology
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    • v.50 no.1
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    • pp.116-125
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    • 2018
  • Modified 9Cr-1Mo ferritic steel is a preferred material for steam generators in nuclear power plants for their creep strength and good corrosion resistance. Austenitic stainless steels, such as type 316LN, are used in the high temperature segments such as reactor pressure vessels and primary piping systems. So, the dissimilar joints between these materials are inevitable. In this investigation, dissimilar joints were fabricated by the Shielded Metal Arc Welding (SMAW) process with Inconel 82/182 filler metals. The notch tensile properties and Charpy V-notch impact toughness properties of various regions of dissimilar metal weld joints (DMWJs) were evaluated as per the standards. The microhardness distribution across the DMWJs was recorded. Microstructural features of different regions were characterized by optical and scanning electron microscopy. Inhomogeneous notch tensile properties were observed across the DMWJs. Impact toughness values of various regions of the DMWJs were slightly higher than the prescribed value. Formation of a carbon-enriched hard zone at the interface between the ferritic steel and the buttering material enhanced the notch tensile properties of the heat-affected-zone (HAZ) of P91. The complex microstructure developed at the interfaces of the DMWJs was the reason for inhomogeneous mechanical properties.