Study of Microstructure and Phase Composition of Creep Resistant Cast Steel

2014 ◽  
Vol 782 ◽  
pp. 335-338
Author(s):  
Renata Chylińska ◽  
Małgorzata Garbiak ◽  
Bogdan Piekarski
Keyword(s):  
Phase Composition ◽  
Cast Steel ◽  
Annealing Process ◽  
Chromium Carbides ◽  
Steel Microstructure ◽  
The Matrix ◽  
Long Time ◽  
Secondary Precipitates ◽  
New Phase ◽  
18Cr Steel

The study presents the results of the identification of the phase composition of creep resistant cast austenitic 30Ni-18Cr steel with the addition of Ti and Nb after the annealing process conducted at 900°C for 10 and 500 hours. The microstructure of the as-cast steel showed mainly the presence of simple carbides. Depending on the alloy chemical composition, those were the TiC and NbC carbides. In the initial phase of annealing process, the nucleation of small secondary precipitates of chromium carbides Cr23C6 was observed to take place in cast steel microstructure at the matrix / simple carbides interface. After a long-time annealing, a new phase (G phase) was developing; the symbols of the phase were Ni16Ti6Si7 and Ni16Nb6Si7, respectively. The G phase was enclosing simple carbides forming with them the complexes of primary and secondary precipitates of a very intricate morphology. Chromium carbides Cr23C6 were also present there.

scholarly journals Wear Resistance of TiC Reinforced Cast Steel Matrix Composite

2017 ◽  
Vol 17 (1) ◽  
pp. 143-146 ◽  
Author(s):  
S. Sobula ◽  
E. Olejnik ◽  
T. Tokarski
Keyword(s):  
Wear Resistance ◽  
Matrix Composite ◽  
Base Alloy ◽  
Cast Steel ◽  
Composite Layer ◽  
Wear Loss ◽  
Steel Matrix ◽  
Soft Matrix ◽  
Base Steel ◽  
The Matrix

Abstract Wear resistance of TiC-cast steel metal matrix composite has been investigated. Composites were obtained with SHSB method known as SHS synthesis during casting. It has been shown the differences in wear between composite and base cast steel. The Miller slurry machine test were used to determine wear loss of the specimens. The slurry was composed of SiC and water. The worn surface of specimens after test, were studied by SEM. Experimental observation has shown that surface of composite zone is not homogenous and consist the matrix lakes. Microscopic observations revealed the long grooves with SiC particles indented in the base alloy area, and spalling pits in the composite area. Due to the presence of TiC carbides on composite layer, specimens with TiC reinforced cast steel exhibited higher abrasion resistance. The wear of TiC reinforced cast steel mechanism was initially by wearing of soft matrix and in second stage by polishing and spalling of TiC. Summary weight loss after 16hr test was 0,14÷0,23 g for composite specimens and 0,90 g for base steel.

Microstructural Aspect of Ageing Process of GP91 Cast Steel

2013 ◽  
Vol 203-204 ◽  
pp. 368-371
Author(s):  
Grzegorz Golański ◽  
Joanna Kępa
Keyword(s):  
Dislocation Density ◽  
Power Plants ◽  
Subgrain Size ◽  
Ageing Time ◽  
Cast Steel ◽  
Phase Identification ◽  
Tem Analysis ◽  
Steel Microstructure ◽  
Mean Diameter ◽  
Microstructural Aspect

The microstructure of 9% Cr cast steel for advanced power plants, serviced at around 580 − 600°C, after ageing has been characterized. The investigated cast steel was subject to ageing at the temperature of 600°C for 6000 and 8000 hrs. Quantitative TEM analysis of the cast steel microstructure was performed to describe the dislocation density within subgrains, the width of martensite subgrains and the M23C6 carbides parameters (shape and mean diameter). Moreover, the phase identification was carried out using electron diffraction. The results have shown that an increase in ageing time at 600°C temperature is the reason for slight increase in the subgrain size, the size of M23C6 carbides and a decrease in dislocation density within subgrains. The MX particle size was not changed. The Laves phase was identified in the cast steel microstructure after 6000 hrs of ageing.

scholarly journals Military Coups d'etat in Nigeria Revisited: A Political and Economic Analysis

1993 ◽  
Vol 14 ◽  
pp. 129-147
Author(s):  
Julius E. Nyangoro
Keyword(s):  
South Africa ◽  
Military Intervention ◽  
Authoritarian Regimes ◽  
African Politics ◽  
Long Time ◽  
Racial Domination ◽  
Coups D'etat ◽  
New Phase ◽  
Radical Transformation

In the last few years, there seems to have been a radical transformation in African politics. South Africa, which for a long time reflected the politics of racial domination, is moving towards multi-racial rule. Formerly one-party states such as Zambia and Kenya recently have held multi-party elections; and authoritarian regimes such as Zaire are now seriously discussing the possibility of pluralist politics. The question that this paper seeks to address is whether the changes taking place are indeed ushering in a new phase of politics in Africa without the prospect of military intervention. Nigeria is used as a case study for examining this question.

scholarly journals Simultaneously Quantitative Analysis of Naringin and Its Major Human Gut Microbial Metabolites Naringenin and 3-(4′-Hydroxyphenyl) Propanoic Acid via Stable Isotope Deuterium-Labeling Coupled with RRLC-MS/MS Method

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4287 ◽  
Author(s):  
Taobin Chen ◽  
Hao Wu ◽  
Yan He ◽  
Wenjun Pan ◽  
Zenghao Yan ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Propanoic Acid ◽  
Microbial Metabolites ◽  
Deuterium Labeling ◽  
Human Gut ◽  
Matrix Interferences ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Long Time ◽  
Active Precursor

Widespread in citrus fruits, naringin, a natural 2,3-dihydroflavonoid, is of particular interest to scientists and has a broad range of beneficial bioactivities to health. Orally administered naringin remains in the gut tract for a relatively long time because of its low bioavailability. Under the metabolism mediated by human gut microbiota, naringin could be an active precursor for derived metabolites to play important physiological roles. However, naringin and its metabolites are hard to accurately quantify due to severe endogenic interference. In this study, an analytical rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS) method coupled with stable isotope deuterium-labeling is developed and validated to simultaneously quantify naringin as well as its major human gut microbial metabolites naringenin and 3-(4′-hydroxyphenyl) propanoic acid. By eliminating the matrix interferences, this strategy not only confirms naringenin and 3-(4′-hydroxyphenyl) propanoic acid as the predominant metabolites which contribute to the pharmacological effects of naringin but also provides a suitable choice for other flavonoid pharmacokinetics study.

scholarly journals Science underpinning the safety case of deep geological repositories − challenges in the past and in the future and how to maintain knowledge and competence during operation

2020 ◽  
Vol 6 ◽  
pp. 24
Author(s):  
Johan Andersson
Keyword(s):  
International Cooperation ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Research Strategy ◽  
Version Control ◽  
The Past ◽  
Safety Case ◽  
Long Time ◽  
New Challenges ◽  
New Phase

Final repositories for spent nuclear fuel are approaching implementation. A prerequisite for these advancements is that it has been shown that the repository can be constructed and operated in practice in such a way that safety can be assured both during operation and over very long time scales. The success rests on decades of structured and objective-driven research and development. A key element of the research strategy has been to ensure adequate in-house competence and expertise. Also, openness and international cooperation are essential. Workable procedures for data qualification, version control as well as internal and external peer review have gained importance. When the programmes now enter a new phase of construction and operation new challenges will arise. Even if the implementing organisations would need to keep a core competence on post closure safety assessment international cooperation will be even more important on developing, sharing and managing the knowledge needed.

Hybrid Comopsites Shaped by Casting Methods

2013 ◽  
Vol 211 ◽  
pp. 47-52 ◽  
Author(s):  
Anna J. Dolata
Keyword(s):  
Thermal Conductivity ◽  
Phase Composition ◽  
Electron Microscope ◽  
Hybrid Composite ◽  
Centrifugal Casting ◽  
Thermal Conditions ◽  
Gravity Casting ◽  
Cast Composites ◽  
The Matrix

In the presented work two methods of casting: gravity casting and centrifugal casting have been described. The main aim of the study was development procedures for producing the AlSi / SiC+C hybrid composite. Composite suspensions with the same phase composition were cast into molds with different coefficients of thermal conductivity. This allowed to determine the influence of thermal conditions on the formation of the structure and distribution of particles in the matrix. In the paper the conditions of casting, macro-and microstructure and selected properties of the casts have been presented. The structure of components and cast composites was examined by light and electron microscope, applying properly made preparations.

Microstructures and Properties of Tungsten Carbide Particle-Reinforced Composites Fabricated by Overlaying Welding with Flux-Cored Wire

2011 ◽  
Vol 228-229 ◽  
pp. 548-551
Author(s):  
Lian Jie Li ◽  
Le Dai
Keyword(s):  
Wear Resistance ◽  
Tungsten Carbide ◽  
Carbide Particle ◽  
Reinforced Composites ◽  
Small Particles ◽  
Cored Wire ◽  
Steel Microstructure ◽  
Surface Iron ◽  
The Matrix ◽  
Surface Rigidity

The wire was made by Tungsten Carbide(WC) particles as core. MIG welding was used to surface iron-based WC wearable composite coating of different size and content of WC particles on mild steel. Microstructure was investigated. Surface rigidity and wear resistance were tested. The results indicate that the small particles are dissolved seriously, which separate out with reticulation. The hardness and wear resistance of the matrix are relative higher. The big particles are dissolved less, tree crystal separates out along particles. The particles are easy to fall off when wearing. So the hardness and wear resistance of the substrate are relative lower. The admixture with 80% big particles and 20% small particles has the best wear resistance, its wear resistance can achieve quintupling of quenching 45 steel. The hardness and wear resistance increase with content of WC increasing.

scholarly journals Influence of Vanadium and Boron Additions on the Microstructure, Fracture Toughness, and Abrasion Resistance of Martensite-Carbide Composite Cast Steel

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Waleed Elghazaly ◽  
R. Rashad ◽  
Sayed Elmohr ◽  
Saied Elghazaly
Keyword(s):  
Fracture Toughness ◽  
Abrasion Resistance ◽  
Cast Steel ◽  
Spare Parts ◽  
Medium Frequency ◽  
Sand Cast ◽  
Industrial Services ◽  
Steel Microstructure ◽  
Steel Castings ◽  
Final Impact

High chromium cast steel alloys are being used extensively in many industrial services where dry or wet abrasion resistance is required. Such steel castings are demanded for cement, stoneware pipes, and earth moving industries. In this research, five steel heats were prepared in 100 kg and one-ton medium frequency induction furnaces and then sand cast in both Y-block and final impact arm spare parts, respectively. Vanadium (0.5–2.5%) and boron (120–150 ppm) were added to the 18Cr-1.9C-0.5Mo steel heats to examine their effects on the steel microstructure, mechanical properties especially impact, fracture toughness and abrasion resistance. Changes in the phase transformation after heat treatment were examined using inverted, SEM-EDX microscopy; however, the abrasion resistance was measured in dry basis using the real tonnage of crushed and milled stoneware clay to less than 0.1 mm size distribution.

Effects of Cr on Microstructure and Hardness of HVOF-Sprayed WC-Co Coating

2011 ◽  
Vol 317-319 ◽  
pp. 301-306 ◽  
Author(s):  
Li Jun Wang ◽  
Hui Chen ◽  
Yan Liu ◽  
Guo Qing Gou ◽  
Da Li
Keyword(s):  
Phase Composition ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Wear And Corrosion ◽  
Application Potential ◽  
Confocal Scanning ◽  
Wear And Corrosion Resistance ◽  
New Phase

In the areas of remanufacturing and working conditions with requirements of wear and corrosion resistance, the WC-Co thermal spray coating has a wide applications. WC-10Co-4Cr is an excellent, has great application potential as a coating composition. In this research, the two kinds of coatings, WC-12Co and WC-10Co-4Cr, were sprayed by high velocity oxygen-flame(HVOF). The phase composition is studied by X-ray diffraction(XRD). The porosity is investigated by lase confocal scanning microscope(LCSM), and the micro-hardness is measured. The results show that, The porosity of two coatings don't differ, this maybe has relation with the parameters in the spraying process.The micro-hardness of WC-10Co-4Cr coating is higher than that of WC-12Co coating. Compared with the phase composition of WC-12Co coating, there are new phase composition Cr7C3, Cr23C6 and Cr2WO6 in the WC-10Co-4Cr coating. And the content of W2C and η phase are reduced in WC-10Co-4Cr coating. Cr had no effect on the lattice transformation of cobalt.

Preparation and Adsorption Performance of GF/EPDM/LLDPE Foaming Composite for Petrol

2012 ◽  
Vol 602-604 ◽  
pp. 1157-1160
Author(s):  
Xiu Qi Liu ◽  
He Qin Xing ◽  
Li Li Zhao ◽  
Dan Wang
Keyword(s):  
Absorption Rate ◽  
Cell Structure ◽  
Oil Absorption ◽  
Melt Blending ◽  
Adsorption Performance ◽  
Internal Cell ◽  
Foam Composite ◽  
The Matrix ◽  
Long Time ◽  
Matrix Reinforcement

In our study, a new kind of material for petrol adsorption was prepared by melt blending and molding foaming with EPDM and LLDPE as the matrix and modified glass fiber (GF) as the filler. LLDPE as the second matrix can improve the matrix reinforcement, the composite cross-linked network density was reduced, but the oil absorption rate was increasing. After recycling three times, the oil absorption rate GF/EPDM foaming composite and GF / LLDPE / EPDM foam composite were changed little, the internal cell structure can exist for a long time and showed good recycling performance.

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