Thermal ageing on the deformation and fracture mechanisms of a duplex stainless steel by quasi in-situ tensile test under OM and SEM

Wang, Yao; Yao, Yuhong; Wang, Z.P.; Jin, Yao; Zhang, X.L.; Liu, J.N.

doi:10.1016/j.msea.2016.04.051

Cited by 22 publications

(10 citation statements)

References 20 publications

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“…In addition, with time increasing these slip lines multiply and coarsen to form several slip bands. Such a phenomenon was also observed by Guo [4] and other researchers [27]. In Figure 5, the slip lines in two adjacent austenite phases tend to form along similar directions, which is almost perpendicular to the loading direction.…”

Section: Stress-strain Behaviorsupporting

confidence: 79%

“…To investigate the slip deformation with time, many in situ or quasi in situ tests have been conducted using CDSS. Guo [4] used an in situ scanning electron microscopy (SEM) technique to study the mechanical properties and slip deformation of an unaged CDSS at various temperatures, ranging from 25 • C to 750 • C. Wang [27] conducted quasi in situ optical microscope (OM) tests on the thermally aged CDSS at room temperature. As the coolant water pipes suffer from the problems of both long-term thermal aging and high-temperature service, it makes a lot of sense to conduct in situ tests on the CDSS at service temperature to investigate the mechanical properties, the slip mechanisms and the damage mechanisms in CDSS.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties of a Thermally-aged Cast Duplex Stainless Steel by in Situ Tensile Test at the Service Temperature

Zhang

Jing

2019

Metals

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Z3CN20.09M cast duplex stainless steel (CDSS) has been used for primary coolant water pipes in pressurized water reactors due to its excellent mechanical properties. Such pipes operate at an elevated service temperature (~320 °C) and experience issues of thermal aging embrittlement. In situ tensile tests were conducted to investigate the deformation mechanisms of Z3CN20.09M CDSS after long-term thermal aging at 475 °C for up to 2000 h in both optical microscope and scanning electron microscope at 320 °C. For the 320 °C tests, the tensile stress and other mechanical properties, e.g. the yield stress and the ultimate tensile strength, increase during the thermal aging process and recover to almost the same level as the unaged condition after annealing heat-treatment, which is caused by the formation and dissolution of precipitation during aging and anneal heat-treatment, respectively. For the slip mechanism, straight slip lines form first in the austenite phase. When these slip lines reach the austenite/ferrite interface, three kinds of slip systems are found in the ferrite phase. During the fracture process, the austenite phase is torn apart and the ferrite phase shows a significant elongation. The role of the ferrite phase is to hold the austenite matrix, thus increasing the tensile strength of this steel.

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Section: Stress-strain Behaviorsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of a Thermally-aged Cast Duplex Stainless Steel by in Situ Tensile Test at the Service Temperature

Zhang

Jing

2019

Metals

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“…In the case of duplex stainless steels, during isothermal heating, at temperatures below 600 • C, few phase transformation mechanisms can occur [16][17][18][19], with the most important one being spinodal decomposition of the δ-phase into coherent α-phase (Fe-enriched) and α'-phase (Cr-enriched), leading to the following important changes in alloy's exhibited mechanical properties: a high decrease of toughness, an increase in hardness, a small decrease in elongation to fracture, and little or no changes in ultimate tensile strength and yield strength [38]. Other important transformation mechanisms that can occur are represented by the precipitation of secondary phases, such as the R-phase, G-phase, and chromium nitrides [12][13][14][15].…”

Section: Discussionmentioning

confidence: 99%

Influence of Aging Treatment on Microstructure and Tensile Properties of a Hot Deformed UNS S32750 Super Duplex Stainless Steel (SDSS) Alloy

Cojocaru

Răducanu

Nocivin

et al. 2020

Metals

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In this present study, the influence of isothermal aging temperature and duration on microstructural and mechanical properties of a hot-deformed UNS S32750 super duplex stainless steel (SDSS) alloy was investigated by SEM-EBSD (scanning electron microscopy-electron backscatter diffraction) and tensile testing techniques. An isothermal aging treatment, at temperatures between 400 and 600 °C and treatment duration between 3 and 120 h, was applied to a commercial UNS S32750 SDSS alloy. Microstructural characteristics of all thermomechanical (TM) processed states, such as distribution and morphology of constituent phases, grain’s modal orientation (MO), and obtained mechanical properties were analysed correlated with the TM processing conditions. The obtained experimental results show that the constituent phases, in all TM processed states, are represented by elongated γ-phase grains within the δ-phase matrix. The R-phase was observed in the case of aging treatment performed at 600 °C for 120 h. Within the δ-phase matrix, dynamically recrystallized grains were identified as a result of applying hot deformation and isothermal aging treatments. Also, it was observed that aging treatment parameters can significantly influence the mechanical behaviour exhibited by the UNS S32750 SDSS alloy, in terms of elongation to fracture and absorbed energy during impact testing.

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“…Dislocation in austenite piled up against the phase boundary and created a local stress concentration, which generated dislocation in ferrite [ 7 ]. At present, many studies have been conducted on the microstructural evolution and mechanical behavior of CDSSs during long-term thermal aging [ 10 , 11 , 12 ]. The main reason is that the ferrite phase in CDSSs will decompose into a Fe-rich α phase and Cr-rich α’ phase, which will cause ferrite phase embrittlement.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Evaluation on Deformation and Fracture Mechanism of Cast Duplex Stainless Steel Tubular Specimen

Wang

Chen

et al. 2020

Materials

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The deformation behavior and fracture mechanism of cast duplex stainless steel tubular specimens under different tensile stages were investigated through experimental and numerical evaluation. The results showed that the axial stress was redistributed due to the necking of the tubular specimen, the axial stress near the internal wall was larger than those near the external wall, and its maximum axial stress was distributed between the internal wall and the center of the wall thickness. Microcracks and voids were initiated under the maximum shear stress along the δ/γ phase interface and propagated to the ferrite interior. The voids were connected and merged into the main crack through the propagation of the microcracks. Moreover, the main crack first propagated to the internal wall and then rapidly propagated to the external wall. The fracture morphology can be divided into three types: shear lip zones that can be found on both the internal and external walls, and shear lip zones that can be found on either only the internal wall or the external wall.

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Thermal ageing on the deformation and fracture mechanisms of a duplex stainless steel by quasi in-situ tensile test under OM and SEM

Cited by 22 publications

References 20 publications

Mechanical Properties of a Thermally-aged Cast Duplex Stainless Steel by in Situ Tensile Test at the Service Temperature

Mechanical Properties of a Thermally-aged Cast Duplex Stainless Steel by in Situ Tensile Test at the Service Temperature

Influence of Aging Treatment on Microstructure and Tensile Properties of a Hot Deformed UNS S32750 Super Duplex Stainless Steel (SDSS) Alloy

Experimental and Numerical Evaluation on Deformation and Fracture Mechanism of Cast Duplex Stainless Steel Tubular Specimen

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