Changes in Microstructure and Mechanical Properties of Cr-Mo Reactor Vessel Steels During Long-Term Service

1985 ◽  
Vol 107 (3) ◽  
pp. 285-294 ◽  
Author(s):  
Y. Nishizaka ◽  
Y. Hara ◽  
A. Hori ◽  
H. Tsukahara ◽  
K. Miyano ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Rupture Strength ◽  
Reactor Vessel ◽  
Steel Matrix ◽  
Metallographic Examination ◽  
Microstructure And Mechanical Properties ◽  
Carbide Morphology ◽  
The Matrix ◽  
Service Environments

Changes in microstructure and mechanical properties of 1Cr-0.5Mo and 2.25Cr-1Mo steels during long-term service have been investigated. The study includes inspection of a 1Cr-0.5Mo steel reactor vessel which operated for 20 yr and tests on specimens that had been exposed to service environments. The reactor vessel, exposed at 490 to 530°C for 170,000 hr (about 20yr), showed appreciable decrease in the room temperature yield strength, impact toughness and creep rupture strength compared with the original properties. The service exposure caused changes in carbide morphology and species, forming M2C and M7C3 carbides and transferring significant amounts of Cr and Mo from the matrix to carbides; only 32 percent of the total Mo and 72 percent of the total Cr remained in the matrix. The microstructure of 2.25Cr-1Mo steel showed higher stability than that of 1Cr-0.5Mo steel, although a similar transfer of Mo and Cr from the matrix to carbides took place. The Mo and Cr contents remaining in the 2.25Cr-1Mo steel matrix after a 2-yr exposure were only 25 and 74 percent, respectively, of the total quantities in the steel. The partitioning of Mo and Cr to carbides could increase the stability of carbides and consequently reduce the carbon content in the matrix. The mechanical properties are influenced by both the change in the composition of the matrix and the change in carbide morphology. The metallographic examination provides useful information, although qualitative at this stage, on the degree of deterioration of materials.

scholarly journals The Effect of Long-Term Impact of Elevated Temperature on Changes in Microstructure and Mechanical Properties of HR3C Steel

2016 ◽  
Vol 61 (2) ◽  
pp. 761-766 ◽  
Author(s):  
A. Zieliński ◽  
M. Sroka ◽  
A. Hernas ◽  
M. Kremzer
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Quantitative Identification ◽  
Working Parameters ◽  
Long Term Impact

Abstract The HR3C is a new steel for pressure components used in the construction of boilers with supercritical working parameters. In the HR3C steel, due to adding Nb and N, the compounds such as MX, CrNbN and M23C6 precipitate during service at elevated temperature, resulting in changes in mechanical properties. This paper presents the results of microstructure investigations after ageing at 650, 700 and 750 °C for 5,000 h. The microstructure investigations were carried out using scanning and transmission electron microscopy. The qualitative and quantitative identification of the existing precipitates was carried out using X-ray analysis of phase composition. The effect elevated temperature on microstructure and mechanical properties of the examined steel was described.

scholarly journals Microstructure and Mechanical Properties of 14Cr-ODS Steels with Zr Addition

2019 ◽  
Vol 38 (2019) ◽  
pp. 404-410 ◽  
Author(s):  
Weijuan Li ◽  
Haijian Xu ◽  
Xiaochun Sha ◽  
Jingsong Meng ◽  
Zhaodong Wang
Keyword(s):  
Mechanical Properties ◽  
Hot Isostatic Pressing ◽  
Oxide Dispersion Strengthened ◽  
Nominal Composition ◽  
Ods Steel ◽  
Zr Addition ◽  
Microstructure And Mechanical Properties ◽  
The Matrix ◽  
Ods Steels ◽  
The Impact

AbstractIn this study, oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–14Cr–2W–0.35Y2O3 (14Cr non Zr-ODS) and Fe–14Cr–2W–0.3Zr–0.35Y2O3 (14Cr–Zr-ODS) were fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP) technique to explore the impact of Zr addition on the microstructure and mechanical properties of 14Cr-ODS steels. Microstructure characterization revealed that Zr addition led to the formation of finer oxides, which was identified as Y4Zr3O12, with denser dispersion in the matrix. The ultimate tensile strength (UTS) of the non Zr-ODS steel is about 1201 MPa, but UTS of the Zr-ODS steel increases to1372 MPa, indicating the enhancement of mechanical properties by Zr addition.

Microstructure and Mechanical Performance of AZ31-1.7 Wt.% Si Alloy Processed by Cyclic Channel Die Compression

2010 ◽  
Vol 667-669 ◽  
pp. 457-461
Author(s):  
Wei Guo ◽  
Qu Dong Wang ◽  
Man Ping Liu ◽  
Tao Peng ◽  
Xin Tao Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Mechanical Performance ◽  
Chinese Script ◽  
Cast State ◽  
Microstructure And Mechanical Properties ◽  
Mean Grain Size ◽  
The Matrix ◽  
The Mean

Cyclic channel die compression (CCDC) of AZ31-1.7 wt.% Si alloy was performed up to 5 passes at 623 K in order to investigate the microstructure and mechanical properties of compressed alloys. The results show that multi-pass CCDC is very effective to refine the matrix grain and Mg2Si phases. After the alloy is processed for 5 passes, the mean grain size decreases from 300 μm of as-cast to 8 μm. Both dendritic and Chinese script type Mg2Si phases break into small polygonal pieces and distribute uniformly in the matrix. The tensile strength increases prominently from 118 MPa to 216 MPa, whereas the hardness of alloy deformed 5 passes only increase by 8.4% compared with as-cast state.

Microstructure, Mechanical Properties, Sintering and Fracture Behavior of Ti(C, N) Based Cermets Granules/Ti(C, N) Based Cermets Composite

2020 ◽  
Vol 837 ◽  
pp. 139-145
Author(s):  
Ai Jun Liu ◽  
Gang Li ◽  
Ning Liu ◽  
Ke Bei Chen ◽  
Hai Dong Yang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Relative Density ◽  
Fracture Behavior ◽  
Rupture Strength ◽  
Binder Phase ◽  
Hard Phase ◽  
Opposite Trend ◽  
The Matrix ◽  
Sintering Properties

Effect of Ti (C,N) based cermets granule on the microstructure, mechanical properties, sintering and fracture behavior of Ti (C,N) based cermets was investigated. Results show that the Ti (C,N) based cermets granules distribute in the matrix homogeneously. A nanoindentation study was performed on hard phase and binder phase in the matrix and granule. With the increase of granules content, sintering properties is worse. With the increase of granules content, transverse rupture strength (TRS) and relative density decrease gradually, while the hardness has an opposite trend. The fracture toughness increases firstly with increasing granule, and then decreases with the further increase of granules. Higher fracture toughness of the cermets is mainly owing to the crack branch and higher fracture energy of coarse granule.

scholarly journals Effect of Trace Yttrium Addition and Heat Treatment on the Microstructure and Mechanical Properties of As-Cast ADC12 Aluminum Alloy

2018 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Jianlong Liu ◽  
Qingjie Wu ◽  
Hong Yan ◽  
Songgen Zhong ◽  
Zhixiang Huang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Primary Si ◽  
Microstructure And Mechanical Properties ◽  
Yttrium Addition ◽  
The Matrix ◽  
The Mean ◽  
Average Size ◽  
Small Average Size

The effects of rare earth yttrium (Y) additions and the heat treatment process on the microstructure and mechanical properties of as-cast ADC12 aluminum alloy have been investigated. The results showed that the primary Si crystals were significantly refined from long axis to fibrous or granular when the Y content was 0.2 wt%. Compared to the matrix, the mean area and aspect ratio were decreased by 92% and 75%, respectively. Moreover, the Si and Fe-rich phases were spheroidized and refined with a small average size during the solid solution. It was also noted that the copper-rich phases were dissolved into the matrix. Correspondingly, it was found that after metamorphic and heat treatment the ultimate tensile strength (UTS), elongation, and, hardness increased by 81.9%, 69.7%, and 74.8%, respectively, compared to the matrix. The improved mechanical properties can primarily be attributed to the optimization of the microstructure and the refinement of various phases.

Microstructure and Mechanical Properties of Mg-Y Alloys

2011 ◽  
Vol 239-242 ◽  
pp. 352-355
Author(s):  
Quan An Li ◽  
Qing Zhang ◽  
Chang Qing Li ◽  
Yao Gui Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Rare Earth ◽  
Melting Point ◽  
Room Temperature ◽  
Optimum Combination ◽  
High Melting ◽  
High Melting Point ◽  
Microstructure And Mechanical Properties ◽  
The Matrix

The effects of 2-12 wt.% Y addition on the microstructure and mechanical properties of as-cast Mg-Y binary alloys have been investigated. The results show that proper content of rare earth Y addition can obviously refine the grains and form high melting point Mg24Y5 phases in the matrix, and improve the microstructure and mechanical properties of the alloys. At room temperature, the optimum combination of ultimate tensile strength and elongation, 195MPa and 7.5%, is obtained in Mg-10 wt.% Y alloy.

The Influence of Composition Segregation to the Microstructure and Mechanical Properties of SA508-3 Steel

2010 ◽  
Vol 146-147 ◽  
pp. 1017-1021 ◽  
Author(s):  
Lu Han Hao ◽  
Ming Yue Sun ◽  
Dian Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Large Scale ◽  
Strength Loss ◽  
Bottom Part ◽  
Microstructure And Mechanical Properties ◽  
Alloyed Cementite ◽  
Energy Dispersion Spectrum ◽  
Composition Segregation ◽  
The Matrix ◽  
Precipitated Phases

A large scale ingot was dissected to study the segregation law of the elements. The influence of composition segregation to the microstructure and mechanical properties of SA508-3 steel was studied by the comparison of three positions on the ingot. Two precipitated phases were approved to be alloyed cementite and molybdenum carbide (Mo2C). It has demonstrated that the middle and upper parts of the ingot were almost the same in compositions except for a slightly difference in the carbon content. The upper part with more carbon included has relatively more carbide precipitation after the performance heat treatment. The bottom part of the ingot has the lowest carbon and molybdenum content, while the reduction in the amount of precipitated carbide was not observed. On the contrary, fine needle-like Mo2C are extensively distributed in the matrix of the bottom part besides a variety of coarse cementite rods. And the data of Energy Dispersion Spectrum (EDS) mapping has suggested that precipitation of Mo2C tends to bring the segregation of impurities. Many large inclusions were found in the bottom part of the ingot, which were considered to be the main reason for the strength loss of this area.

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