• Title/Summary/Keyword: Tensile Fracture Property

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High Temperature Tensile Property of Transient Liquid Bonded Joints of Ni-base Single Crystal Superalloy (액상확산접합한 Ni기 단결정 초내열합금의 고온인장특성)

  • 김대업;강정윤
    • Journal of Welding and Joining
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    • v.18 no.3
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    • pp.106-113
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    • 2000
  • Single crystallization behavior ad high temperature tensile properties of TLP bonded joints of Ni-base single crystal superalloy, CMSX-2 were investigated using MBF-80 and F-24 insert metals. CMSX-2 was bonded at 1523~1548K for 1.5~1.8ks in vacuum. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. Crystallographic orientation analyzed points over the bonded region possessed the almost same orientation across the joint interface and misorientation $\Delta^{\theta}$ was negligibly small in as-bonded and post-bond heat-treated situations. It was confirmed that single crystallization could be readily achieved during TLP bonding. The tensile strengths of all joints at elevated temperatures were equal to or greater than those of base metal the range of testing temperature between 923K and 1173K. The elongation and reduction of area in values were almost the same as those of base metal. SEM observation of the fracture surfaces of joints after tensile test revealed that the fracture surface indicated the similar morphologies each other, and that the fracture of joints occurred in the base metal in any cases.

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ANALYSIS OF NECKING DEFORMATION AND FRACTURE CHARACTERISTICS OF IRRADIATED A533B RPV STEEL

  • Kim, Jin Weon;Byun, Thak Sang
    • Nuclear Engineering and Technology
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    • v.44 no.8
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    • pp.953-960
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    • 2012
  • This paper reports the irradiation effect on the deformation behavior and tensile fracture properties of A533B RPV steel. An inverse identification technique using iterative finite element (FE) simulation was used to determine those properties from tensile data for the A533B RPV steel irradiated at 65 to $100^{\circ}C$ and deformed at room temperature. FE simulation revealed that the plastic instability at yield followed by softening for higher doses was related to the occurrence of localized necking immediately after yielding. The strain-hardening rate in the equivalent true stress-true strain relationship was still positive during the necking deformation. The tensile fracture stress was less dependent on the irradiation dose, whereas the tensile fracture strain and fracture energy decreased with increasing dose level up to 0.1 dpa and then became saturated. However, the tensile fracture strain and fracture energy still remained high after high-dose irradiation, which is associated with a large amount of ductility during the necking deformation for irradiated A533B RPV steel.

Evaluation of Mechanical Properties in Inconel 82/182 Dissimilar Metal Welds (인코넬 82/182 이종금속 용접부의 기계물성 평가)

  • Lee, Joung-Hoon;Jang, Chang-Heui;Kim, Jong-Sung;Jin, Tae-Eun
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.244-249
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    • 2007
  • In several locations of the pressurized water reactors, dissimilar metal welds using inconel welding wires are used to join the low alloy steel nozzles to stainless steel pipes. To evaluate the integrity and design the dissimilar welds, tensile and fracture properties variations are needed. In this study, dissimilar metal welds composed of SA508 Gr.3 LAS, inconel 82/182 weld, and TP316 stainless steel were prepared by gas tungsten arc welding and shielded metal arc welding technique. Microstructures were observed using optical and electron microscopes. Different tensile and fracture properties were observed depending on the specimen sampling position at room temperature and $320^{\circ}C,$ and that was discussed based on the microstructure characteristics. It was found that the strength at the bottom of weld was greater than at the top of the weld. Also, from the test data using small punch specimen, more detailed tensile property variations were evaluated.

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A Study on Statistical Nature of Fatigue Fracture Toughness (피로파괴 인성치의 통계적 성질에 관한 연구)

  • 오환교;김희송
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.11
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    • pp.2894-2901
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    • 1994
  • Many researchers presented a probabilistic and statistical property of the material strength. However, the study on probabilistic and statistical property of fatigue fracture toughness has not been nearly presented. Major objectives in this paper are to compare the statistical test results of fatigue fracture toughness with those obtained in the tensile experiments, and to recognize the size effect for the probabilistic and statistical property by using specimens with various thickness.

Effects of Cr Content and Volume Fraction of δ-Ferrite on Thermal Cycling Fatigue Properties of Overlay Welded Heat-Resistant 12%Cr Stainless Steels (내열용 오버레이 12%Cr계 스테인레스강의 열피로 특성에 미치는 Cr 함량과 델타-페라이트의 영향)

  • Jung, J.Y.
    • Transactions of Materials Processing
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    • v.26 no.6
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    • pp.356-364
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    • 2017
  • In this study, submerged arc cladded Fe-Cr-Ni-Mo-CuWNbV-C stainless steels containing various Cr contents between 11.2 wt.% and 16.7 wt.% were prepared with fixed C content at about 0.14 wt.%. Using these alloys, changes in microstructure, tensile property, and thermal fatigue property were investigated. Phase fraction of delta-ferrite was increased gradually with increasing Cr content. However, tensile strength, hardness, and thermal fatigue resistance appeared to be decreased. When the microstructure of delta-ferrite was observed, it was revealed that the mesh structure retained up to about 15% Cr content. Although thermal fatigue resistance was almost the same for Cr contents between 11.0 and 14.5 wt.%, it was significantly decreased at higher Cr contents. This was evident from mean value of crack lengths of 10 largest ones. Evaluation of thermal fatigue resistance on alloys with various Cr contents revealed the following important results. First, the reproducibility of ranking test was excellent regardless of the number of cycles. Second, thermal fatigue resistance was increased in proportion to true tensile fracture strength values of overlay materials. Finally, the number of thermal fatigue cracks per unit length was increased with increasing true tensile fracture strength.

Application of Advanced Indentation System for Evaluati Tensile Property Degradation of Cr-Mo Steel (Cr-Mo 강의 열화도 평가를 위한 Advanced Indentation System의 응용)

  • Jang, Jae-Il;Choi, Yoel;Lee, Yun-Hee;Kwon, Dong-Il;Kim, Jeoung-Tae
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.231-236
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    • 2001
  • A newly developed Advanced Indentation System (AIS), which is a portable and nondestructive system for evaluating tensile properties, was used to measure mechanical behavior of materials used under high temperature and pressure conditions. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. Aging effects of Cr-Mo and Cr-Mo-V steel at high temperature were simulated. Tensile properties including yield strength and tensile strength at various temperature are obtained from the test. For all test materials and conditions, the AIS-derived results were in good agreement with those from conventional standard test method. Examples of the test results ate given and potential applications of the AIS to assess the integrity of aging structures are briefly discussed.

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Evaluation of Microstructure and Mechanical Property of Inconel 600 Degraded under High Temperature (고온 열화된 Inconel 600강의 미세조직 및 기계적 특성 평가)

  • Jung, Kwang-Hu;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.50 no.6
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    • pp.492-497
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    • 2017
  • In this study, we investigated the effect of thermal aging on mechanical characteristics of Inconel 600 nickel-based alloy. The thermal aging was conducted up to 1000 hours at an atmosphere of $650^{\circ}C$. The microstructure of thermally aged specimens was investigated by an optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). In addition, tensile test (strain rate: 2 mm/min) and micro Vickers hardness test were conducted to evaluate mechanical properties with time. As a result of the experiment, Cr-rich carbide continuously precipitated during thermal aging, leading to the change of the mechanical characteristics and fracture mode. With the increase of aging time, tensile strength, yield strength, and hardness gradually decreased. The fracture mode changed from ductile to brittle with the increase of grain boundary carbide.

Effect of Ni and Mo Addition on Fatique Property in 12Cr Steel (12Cr강의 피로특성에 미치는 Ni+Mo 첨가의 영향)

  • Lee, Jin-Kyung;Bae, Dong-Su
    • Journal of the Korean Society of Industry Convergence
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    • v.24 no.4_2
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    • pp.435-441
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    • 2021
  • This research was performed to study the effect of the Ni + Mo addition on the fatigue properties in 12Cr steel. After heat treatment of 12Cr steel and 12Cr-Ni-Mo steel, tensile tests, impact tests, hardness tests, and rotary bending fatigue tests were performed, respectively. The fatigue fracture surface was observed and analyzed using SEM and EDS. The fatigue limit of 12Cr steel was 554 MPa, which was 49 MPa higher than 505 MPa of 12Cr-Ni-Mo steel. Striations, which are the shape of the typical fatigue fracture surface, were observed at the fracture surface near the starting point of fatigue fracture in the 12Cr steel and 12Cr-Ni-Mo steel. However, unlike the case of 12Cr steel, 12Cr-Ni-Mo steel also had a mixed fracture surface with the fatigue and the ductile fracture surface. When brittle non-metallic inclusions exist near the starting point of fatigue failure, the crack propagation was further promoted and the fatigue life was drastically reduced.

Evaluation of Stress-Strain Characteristics of Weldment in Natural Gas Pipeline Using Advanced Indentation System (Advanced Indentation System을 이용한 천연가스배관 용접열영향부의 응력-변형률 변화 특성 분석)

  • Jang, Jae-Il;Son, Dong-Il;Kwon, Dong-Il;Kim, Woo-Sik;Park, Joo-Seung
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.483-488
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    • 2001
  • Until now, the tensile properties of materials can be obtained just in accordance with conventional tensile testing methods which are described in several standards such as ASTM (American Society for Testing and Materials) standard and BS (British Standard). For some cases including on-service facility materials, however, the standard testing methods cannot be applicable due to the destructive testing procedure and specimen size requirement. Therefore, simple, non-destructive and advanced indentation technique was proposed. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. In this paper, the research trend of non-destructive evaluation of tensile properties using AIS (advanced indentation system) and its application fields are reviewed and discussed.

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Static Tensile Strength Evaluation of Notched Coeposite Materials (노치를 갖는 복합재료의 정적강도평가(I))

  • 김윤해;김영식;서곡홍신
    • Journal of Ocean Engineering and Technology
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    • v.7 no.2
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    • pp.19-29
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    • 1993
  • The static tensile tests of GFRP, ID300, CFRID300 and CFRPEEK were made on the plain and notched specimens at room temperature. The results were discussed based on linear notch mechanics which was proposed by H.Nistani. The fracture of notched GFRP, ID300, CFRID300 and CFRPEEK specimens is controlled by the elastic maximum stress, $({\sigma}_max)$, and the notch root racius,$\rho$, alone, independently of the other geometrical conditions. The relation between fracture nominal stress,$({\sigma}_max)$, and stress concentration factor, $K_t$ and a part where $({\sigma}_c)$ is nearly constant independent of $K_t$. A similar phenomenon can be seen in the fatigue tests of notched specimes under rotating bending or push-pull. The almost constant $({\sigma}_c)$ values correspond to the nearly constant apparent stress intensity factor, $K_{1pc}$ values, obtained by assuming ,$\rho$=0. This can be attributed to the existence of the stable crack. Linear notch mechanics is very useful for analyzing the static tensile fracture behavior of notched GFRP, ID300, CFRPEEK specimens.

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