scholarly journals The Analysis of AISI A3 Type Ferritic-Austenitic Cast Steel Crystallization Mechanism

2017 ◽  
Vol 17 (3) ◽  
pp. 229-233
Author(s):  
G. Stradomski
Keyword(s):  
Power Plants ◽  
Cast Steel ◽  
Construction Materials ◽  
Austenitic Steels ◽  
High Alloy ◽  
Working Environments ◽  
Cast Steels ◽  
Derivative Analysis ◽  
Duplex Steel ◽  
The Rich

AbstractHigh-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel.The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich chemical composition and phenomena occurring during crystallization, must be known to the technologists.The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative analysis.

scholarly journals Influence of Copper Addition on Sigma Phase Precipitation during Hot Deformation of Duplex Steel

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1665
Author(s):  
Grzegorz Stradomski ◽  
Arkadiusz Szarek ◽  
Dariusz Rydz
Keyword(s):  
Hot Deformation ◽  
Sigma Phase ◽  
Austenitic Steels ◽  
Multiphase Microstructure ◽  
Copper Addition ◽  
Cast Steels ◽  
Duplex Steel ◽  
Similar Chemical ◽  
Precipitation Phenomena ◽  
The Many

The paper presents an experimental study on microstructure changes in duplex steel after hot deformation. Duplex steels and cast steels are characterized by a multiphase microstructure. They are relatively new materials with great contributions to the many fields of industries. Due to the fact of deforming two different phase austenite and ferrite those materials have a complex plasticity. This work is a continuation and complementation of previous works and is a significant supplement to information presented in them. The article concerns precipitation phenomena and changes in the microstructure of two grades of ferritic-austenitic steels: X2CrNiMoN25-7-4 and X2CrNiMoCuN25-6-3. Those steels have a very similar chemical composition, differing by only 2.5% copper content. An important aspect presented in the work is we observed that adding 2.5% copper prevented precipitation of the destructive sigma phase during the hot deformation.

scholarly journals Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 307
Author(s):  
Matthias Bruchhausen ◽  
Gintautas Dundulis ◽  
Alec McLennan ◽  
Sergio Arrieta ◽  
Tim Austin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Rate ◽  
Power Plants ◽  
Research Effort ◽  
Hold Time ◽  
Strain Range ◽  
Austenitic Steels ◽  
Mean Strain

A substantial amount of research effort has been applied to the field of environmentally assisted fatigue (EAF) due to the requirement to account for the EAF behaviour of metals for existing and new build nuclear power plants. We present the results of the European project INcreasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment (INCEFA-PLUS), during which the sensitivities of strain range, environment, surface roughness, mean strain and hold times, as well as their interactions on the fatigue life of austenitic steels has been characterized. The project included a test campaign, during which more than 250 fatigue tests were performed. The tests did not reveal a significant effect of mean strain or hold time on fatigue life. An empirical model describing the fatigue life as a function of strain rate, environment and surface roughness is developed. There is evidence for statistically significant interaction effects between surface roughness and the environment, as well as between surface roughness and strain range. However, their impact on fatigue life is so small that they are not practically relevant and can in most cases be neglected. Reducing the environmental impact on fatigue life by modifying the temperature or strain rate leads to an increase of the fatigue life in agreement with predictions based on NUREG/CR-6909. A limited sub-programme on the sensitivity of hold times at elevated temperature at zero force conditions and at elevated temperature did not show the beneficial effect on fatigue life found in another study.

scholarly journals Development of Universal Mould Geometry for the Teeming of Cylindrical Iron-Base Alloy Ingots

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 471
Author(s):  
Josef Odehnal ◽  
Pavel Ludvík ◽  
Tomáš Studecký ◽  
Pavel Michálek
Keyword(s):  
Alloy Steel ◽  
Base Alloy ◽  
Cast Steel ◽  
Solidification Process ◽  
High Alloy ◽  
High Alloy Steel ◽  
Iron Base Alloy ◽  
Steel Grades ◽  
Borated Stainless Steel ◽  
Filling And Solidification

The presented work is aimed at developing a mould geometry suitable for casting both low- and high-alloy steel grades into 500 kg experimental ingots. The high Height-to-Diameter (H/D)-ratio mould currently used in COMTES FHT Inc. served as a reference and for finite element method simulations (FEM) of the filling and solidification process. The optimized mould geometry, balancing the porosity and segregations, was determined using MAGMA software. Four different steel grades were defined for the simulation. Case studies were carried out for 34CrNiMo6 (W.Nr. 1.6582), DHQ8, CB2 and borated stainless steel grades ranging from low-alloy steel to high-alloy steel. Extended user-defined criteria and verified boundary conditions were used to predict the formation of A-segregations in cast steel. Both primary (PDAS) and secondary (SDAS) arm spacings were modelled as well. The optimized mould shape and the casting assembly were designed based on the simulation results.

scholarly journals Can Hydropower Still Be Considered a Clean Energy Source? Compelling Evidence from a Middle-Sized Hydropower Station in China

2019 ◽  
Vol 11 (16) ◽  
pp. 4261 ◽  
Author(s):  
Xuerong Li ◽  
Faliang Gui ◽  
Qingpeng Li
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Construction Materials ◽  
Ghg Emissions ◽  
Energy Resource ◽  
Clean Energy ◽  
Hydropower Station ◽  
Intergovernmental Panel ◽  
Fossil Carbon ◽  
Global Economic Growth

The development of clean energy is of great importance in alleviating both the energy crisis and environmental pollution resulting from rapid global economic growth. Hydroelectric generation is considered climate benign, as it neither requires fossil carbon to produce energy nor emits large amounts of greenhouse gases (GHG), unlike conventional energy generation techniques such as coal and oil power plants. However, dams and their associated reservoirs are not entirely GHG-neutral and their classification as a clean source of energy requires further investigation. This study evaluated the environmental impact of the Xiajiang hydropower station based on life cycle assessment (LCA) according to the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines, focusing specifically on GHG emissions after the submersion of the reservoir. Results reveal that although hydropower is not as clean as we thought, it is still an absolute “low emissions” power type in China. The amount of GHG emissions produced by this station is 3.72 million tons with an emissions coefficient of 32.63 g CO2eq/kWh. This figure is lower than that of thermal power, thus implying that hydropower is still a clean energy resource in China. Our recommendations to further minimize the environmental impacts of this station are the optimization of relevant structural designs, the utilization of new and improved construction materials, and the extension of farmland lifting technology.

Innovational Construction Materials of LLP “EcostroyNII-PV” Production

2021 ◽  
Vol 410 ◽  
pp. 806-811
Author(s):  
Kapar Sh. Aryngazin ◽  
Alexey V. Bogomolov ◽  
Askar K. Tleulessov
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Construction Materials ◽  
Electric Power Industry ◽  
Steelmaking Slag ◽  
Alumina Production ◽  
Building Products ◽  
Operational Characteristics ◽  
Ash And Slag Waste ◽  
Slag Waste

The article discusses the experience of recycling industrial waste from the electric power industry and metallurgy. Based on the experience of Ecostroy NII-PV LLP. The proposed technology for manufacturing building products from ash and slag waste provides innovative compositions of raw mixtures. What provides an increase in operational characteristics and labor productivity in construction. The applied technology, in comparison with the existing analogues, provides for the use of local waste (ash and slag waste from the combustion of Ekibastuz coal, bauxite sludge from the Pavlodar aluminum plant, steel-making slags), differing in chemical and granulometric composition. as well as binding properties from other analogs and prototypes. In the manufacture of building products introduced mixture, including, wt %: slag Portland cement - 14.32-17.00; sand - 18.74-25.52, crushed stone - 46.50-49.71, sludge from alumina production obtained during the recycling of bauxite from Kazakhstan - 5-7; self-disintegrating steelmaking slag - 5-7; ash and slag waste from thermal power plants from burning Ekibastuz coals - 5-7. According to the test results, the average tensile strength of building products (paving slabs, curbs, hollow bricks) is 3.2 - 3.8 MPa (strength class V2.5).

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.

Thermo-Economic Analysis of Microalgae Co-Firing Process for Fossil Fuel-Fired Power Plants

2010 ◽  
Author(s):  
Jian Ma ◽  
Oliver Hemmers
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Power Plants ◽  
Fossil Fuel ◽  
Construction Materials ◽  
Ghg Emissions ◽  
Combustion Efficiency ◽  
Pure Oxygen ◽  
Firing Process ◽  
Microalgal Biomass

A thermoeconomic analysis of microalgae co-firing process for fossil fuel-fired power plants is studied. A process with closed photobioreactor and artificial illumination is evaluated for microalgae cultivation, due to its simplicity with less influence from climate variations. The results from this process would contribute to further estimation of process performance and investment. The concept of co-firing (coal-microalgae or natural gas-microalgae) includes the utilization of CO2 from power plant for microalgal biomass culture and oxy-combustion of using oxygen generated by biomass to enhance the combustion efficiency. As it reduces CO2 emission by recycling it and uses less fossil fuel, there are concomitant benefits of reduced GHG emissions. The by-products (oxygen) of microalgal biomass can be mixed with air or recycled flue gas prior to combustion, which will have the benefits of lower nitrogen oxide concentration in flue gas, higher efficiency of combustion, and not too high temperature (avoided by available construction materials) resulting from coal combustion in pure oxygen. Two case studies show that there are average savings about $0.386 million/MW/yr and $0.323 million/MW/yr for coal-fired and natural gas-fired power plants, respectively. These costs saving are economically attractive and demonstrate the promise of microalgae technology for reducing greenhouse gas (GHG) emission.

scholarly journals The Structure of the Silumin Coat on Alloy Cast Steels

2012 ◽  
Vol 12 (2) ◽  
pp. 215-220
Author(s):  
T. Szymczak
Keyword(s):  
Phase Structure ◽  
High Speed ◽  
Cast Steel ◽  
Intermetallic Phases ◽  
External Layer ◽  
Cast Steels ◽  
Steel Grades ◽  
The Absolute ◽  
The Given ◽  
Alloy Cast

The Structure of the Silumin Coat on Alloy Cast Steels The work presents the analysis results of the structure of the coat obtained by dipping in silumin AlSi5 of two grades of alloy cast steel: GX6CrNiTi18-10 (LH18N9T) and GX39Cr13 (LH14). The temperature of the silumin bath was 750±5°C, and the hold-up time of the cast steel element τ = 180 s. The absolute thickness of the coat obtained in the given conditions was g = 104 μm on cast steel GX6CrNiTi18-10 and g = 132 μm on GX39Cr13. The obtained coat consisted of three layers of different phase structure. The first layer from the base "g1" was constructed of the phase AlFe including Si and alloy additives of the tested cast steel grades: Cr and Ni (GX6CrNiTi18-10) and Cr (GX39Cr13). The second layer "g1" of intermetallic phases AlFe which also contains Si and Cr crystallizes on it. The last, external layer "g2" of the coat consists of the silumin containing the intermetallic phases AlFeSi which additionally can contain alloy additives of the cast steel. It was shown that there were no carbides on the coat of the tested cast steels which are the component of their microstructure, as it took place in the case of the coat on the high speed steels.

scholarly journals Innovation potentials for construction materials with specific focus on the challenges in Africa

2020 ◽  
Vol 5 ◽  
pp. 63-74
Author(s):  
Wolfram Schmidt ◽  
Mike Otieno ◽  
Kolawole Olonade ◽  
Nonkululeko Radebe ◽  
Henri Van-Damme ◽  
...  
Keyword(s):  
Environmental Sustainability ◽  
Construction Materials ◽  
Cementitious Materials ◽  
Sustainable Construction ◽  
African Continent ◽  
Concrete Technology ◽  
Rich Diversity ◽  
The Rich ◽  
Basic Infrastructure ◽  
Industrialised Countries

Africa is urgently in need of adequate basic infrastructure and housing, and it is one of the continents where massive construction activities are on the rise. There is a vast variety of potentially viable resources for sustainable construction on the continents, and consequently, the continent can bring innovative, greener technologies based on local sources effectively into practice. However, unlike established concrete constituents from industrialised countries in the global North, most of the innovation potentials from the African continent have not yet been the focus of intensive fundamental and applied research. This clearly limits the implementation of more sustainable local technologies. This paper presents a case for the need to first appreciate the rich diversity and versatility of the African continent which is often not realistically perceived and appreciated. It discusses specific innovation potentials and challenges for cementitious materials and concrete technology based on local materials derived from sources on the African continent. The unique African materials solutions are presented and discussed, from mineral binders over chemical admixtures and fibres to reinforcement and aggregates. Due to the pressing challenges faced by Africa, with regards to population growth and urbanisation, the focus is not only put on the technological (durability, robustness and safety) and environmental sustainability, but also strongly on socio-economic applicability, adaptability and scalability. This includes a review of alternative, traditional and vernacular construction technologies such as materials-saving structures that help reducing cementitious materials. Eventually, a strategic research roadmap is hypothesised that points out the most relevant potentials and research needs for quick implementation of more localised construction materials.

Sign in / Sign up

Export Citation Format

Share Document