scholarly journals High Temperature Strength of Cast Irons for Cylinder Heads

2018 ◽  
Vol 925 ◽  
pp. 385-392 ◽  
Author(s):  
Wilson Luiz Guesser ◽  
Carlos S. Cabezas ◽  
Luis Carlos Guedes ◽  
André M. Zanatta
Keyword(s):  
High Performance ◽  
Tensile Tests ◽  
Gray Iron ◽  
Fracture Mechanisms ◽  
High Temperature Strength ◽  
Strength Increase ◽  
Cast Irons ◽  
Compacted Graphite ◽  
Graphite Structure ◽  
Iron Grade

Hot strength and fracture mechanisms in high quality cast irons were studied, comparing the standard gray iron Grade 300, alloyed with Mo, typically used for cylinder heads in high power engines, with other two materials: one gray iron Grade 300, obtained through graphite refinement and one compacted graphite iron, Grade 450. In these last two materials, the strength increase was obtained by changing the graphite structure, not by hardening the matrix. The experimental results with tensile tests carried out up to 500 °C show that the different strengthening mechanisms, use of Mo or modification of the graphite structure, are both efficient for increasing the strength at room temperature as well as at high temperatures. The CGI has a lower strength reduction with temperature than the gray irons, which shows the significant impact of the compacted graphite shape in reducing the notch effect. These results show the enormous potential of CGI in cylinder heads for high-performance engines.

scholarly journals A Fatigue and Fracture Study on High Strength Cast Irons

2018 ◽  
Vol 925 ◽  
pp. 296-303 ◽  
Author(s):  
Wilson Luiz Guesser ◽  
Luis Carlos Guedes ◽  
Ailton L. Müller ◽  
Vagner B. Demetrio ◽  
Alexsandro Rabelo
Keyword(s):  
Fatigue Strength ◽  
High Strength ◽  
Gray Iron ◽  
Matrix Interface ◽  
Cast Irons ◽  
Fracture Surfaces ◽  
Graphite Matrix ◽  
Fatigue And Fracture ◽  
Fracture Study ◽  
Iron Grade

Fatigue strength and fracture of high strength cast irons, gray iron grade 300 and CGI grade 450, used for producing lightweight cylinder blocks, were studied. The results show endurance ratios of 0.27-0.28 and 0.38 for gray irons and CGI, respectively. The fracture surfaces in cast irons in general show the predominance of graphite and graphite/matrix interface; however, in CGI there is a larger proportion of fractured pearlitic matrix than in gray iron. This fact, and the differences in the morphology of the graphite/matrix interface, flat in gray iron, rough in CGI, explain the higher results of fatigue strength in CGI compared to gray iron. The results of fatigue strength are compared with the literature and with previous works.

Effects of Graphite Shape on Thermal Fatigue Property of Thin Wall Graphitic Cast Irons

2010 ◽  
Vol 457 ◽  
pp. 398-403 ◽  
Author(s):  
Yung Ning Pan ◽  
Chen Chi Fan ◽  
Chih Hung Chang
Keyword(s):  
Thin Section ◽  
Thermal Fatigue ◽  
Fatigue Property ◽  
Spheroidal Graphite ◽  
Thin Wall ◽  
Flake Graphite ◽  
Cast Irons ◽  
Thin Sections ◽  
Compacted Graphite ◽  
Graphite Structure

The optimal alloy design and microstructure for the high temperature (around 800oC) constrained cyclic thermal fatigue applications in thin-section ductile irons have been established previously by the authors. This study intends to investigate the effect of graphite morphology on the thermal fatigue property of thin-section (2mm ~ 6mm) graphitic cast irons. The results show that to produce carbide-free spheroidal graphite irons in relatively thin sections of 2-mm or 3-mm in the as cast conditions is feasible. However, for compacted graphite cast irons, graphite particles largely in nodular form always occurs in rather thin sections, and acceptable compacted graphite structure can only be obtained when the section thickness exceeds about 6-mm. Regarding the constrained cyclic thermal fatigue property (20 ~ 800oC), cast irons with spheroidal graphite exhibit the best thermal fatigue life, which is followed by irons with compacted graphite, and then flake graphite cast irons, even though flake graphite cast irons show least swelling or distortion after cyclic thermal fatigue test. Furthermore, adding some 0.5%Mo to the irons significantly improves the thermal fatigue property, in some cases even by a factor of 2, implying that the role of Mo outweighs the influence of graphite structure in promoting thermal fatigue property.

Co-cooking nonwoods with hardwoods

TAPPI Journal ◽  
2014 ◽  
Vol 13 (6) ◽  
pp. 19-24
Author(s):  
TROY RUNGE ◽  
CHUNHUI ZHANG
Keyword(s):  
High Performance Liquid Chromatography ◽  
High Performance ◽  
Paper Industry ◽  
Pulp And Paper Industry ◽  
Strength Properties ◽  
Agricultural Residues ◽  
Kraft Pulping ◽  
Pulp And Paper ◽  
Strength Increase ◽  
Xylan Content

Agricultural residues and energy crops are promising resources that can be utilized in the pulp and paper industry. This study examines the potential of co-cooking nonwood materials with hardwoods as means to incorporate nonwood material into a paper furnish. Specifically, miscanthus, switchgrass, and corn stover were substituted for poplar hardwood chips in the amounts of 10 wt %, 20 wt %, and 30 wt %, and the blends were subjected to kraft pulping experiments. The pulps were then bleached with an OD(EP)D sequence and then refined and formed into handsheets to characterize their physical properties. Surprisingly, all three co-cooked pulps showed improved strength properties (up to 35%). Sugar measurement of the pulps by high-performance liquid chromatography suggested that the strength increase correlated with enriched xylan content.

The Effect of Fine M2C (M: Mo, Cr, Fe) Particles on the Recrystallization Temperature and High Temperature Strength of Warm Rolled Fe3Al Based Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Satoru Kobayashi ◽  
Takayuki Takasugi
Keyword(s):  
High Temperature ◽  
Tensile Tests ◽  
Warm Rolling ◽  
Recrystallization Temperature ◽  
High Temperature Strength ◽  
Proof Stress ◽  
Mo Content

ABSTRACTThe effect of fine M2C particles on the recrystallization temperature and high temperature strength of warm rolled Fe3Al base alloys was investigated. Fe-27Al-1.2C-2Cr-xMo (x: 0.3, 0.9) alloys (in at.%) were arc melted, warm rolled and annealed. TEM observations have revealed that fine M2C particles were present in the alloy containing 0.9% Mo but not in the alloy with 0.3% Mo after warm rolling. The recrystallization temperature increased from 740 °C to 810 °C when the Mo content is increased from 0.3 to 0.9 due to the presence of fine M2C particles. Tensile tests conducted on annealed samples with fine sub-grained matrix have shown that the introduction of fine M2C particles is effective to enhance the proof stress at 600 °C.

scholarly journals 3D characterization of the fracture mechanisms of a Fe-rich Al-Si-Cu alloy

2018 ◽  
Vol 165 ◽  
pp. 04006
Author(s):  
Angelika Brueckner-Foit ◽  
Inigo Bacaicoa ◽  
Martin Luetje ◽  
Marcel Wicke ◽  
Andreas Geisert ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Crack Advance ◽  
Micro Computed Tomography ◽  
Initiation Mechanism ◽  
Initiation Phase ◽  
Β Phase ◽  
Cu Alloy

The effect of the defect size and morphology on the fatigue damage evolution was analysed in a recycled Al-Si-Cu alloy by micro-computed tomography and scanning electron microscopy. Fatigue tests were performed and the different crack initiation scenarios were characterized and classified. The interaction between shrinkage and gas pores was the key crack initiation mechanism and the ß-Al5FeSi particles did not play any role in the crack initiation phase. However, crack path analysis indicated that there is a certain amount of crack advance by brittle fracture of the β-phase particles. This is in accordance with the findings of tensile tests in which the ductility depended strongly on the iron content.

scholarly journals Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

2021 ◽  
Author(s):  
Jin Hyung Cho ◽  
Johan Martinsson ◽  
Du Sichen ◽  
Joo Hyun Park
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Nuclear Power ◽  
High Performance ◽  
Internal Combustion Engines ◽  
Sulfide Capacity ◽  
Metal Phase ◽  
High Temperature Strength ◽  
Desulfurization Rate

AbstractNi-based superalloy, which has excellent high-temperature strength and corrosion resistance, is mainly used in aviation materials, high-performance internal combustion engines, and turbines for thermal and nuclear power generation. For this reason, refining the impurities in Ni-based superalloys is a very important technical task. Nevertheless, the original technology for the melting and refining of Ni-based superalloys is still insufficient. Therefore, in this study, the effect of the CaO-Al2O3-MgO-TiO2 slag on the removal efficiency of an impurity element sulfur in Incoloy® 825 superalloy, one of the representative Ni-based superalloys, was investigated. The desulfurization behavior according to the change of TiO2 content and CaO/Al2O3 (=C/A, basicity) ratio as experimental variables was observed at 1773 K (1500 °C). Although the TiO2 content in the slag increases to 15 mass pct, the mass transfer coefficient of sulfur in molten alloy showed a constant value. Alternatively, under the condition of C/A > 1.0 of slag, the mass transfer coefficient of sulfur showed a constant value, whereas under the condition of C/A < 1.0, the mass transfer coefficient of sulfur greatly decreased as CaO decreased. Hence, in the desulfurization of Incoloy® 825 superalloy using the CaO-Al2O3-MgO-TiO2 slag, the TiO2 content in the slag does not have a considerable effect on the desulfurization rate and desulfurization mechanism (metal phase mass transfer controlled regime), but the basicity of the slag has a significant effect on desulfurization mechanism. When the slag basicity decreases below the critical level, i.e., C/A < 1.0, which is corresponding to sulfur distribution ratio, Ls < 200, it was confirmed that the desulfurization mechanism shifts from the metal phase mass transfer-controlled regime to the slag phase mass transfer-controlled regime due to the variation in the physicochemical properties of the slag such as viscosity and sulfide capacity. In addition, the different desulfurization rates between steel and Ni alloy melts were discussed by employing the diffusivity of sulfur in both systems.

scholarly journals The Influence of Titanium as a Desferoidizing Element on the Stability of Production of Magnesium Cast Irons with Compacted Graphite

2021 ◽  
Vol 43 (4) ◽  
pp. 654-666
Author(s):  
V. Aulin ◽  
V. Kropivny ◽  
O. Kuzyk ◽  
O. Lyashuk ◽  
M. Bosyi ◽  
...  
Keyword(s):  
Cast Irons ◽  
Compacted Graphite ◽  
The Stability

scholarly journals Calibration Method for Monitoring Hygro-Mechanical Reactions of Pine and Oak Wood by Acoustic Emission Nondestructive Testing

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3775
Author(s):  
Chiara Bertolin ◽  
Lavinia de Ferri ◽  
Filippo Berto
Keyword(s):  
Acoustic Emission ◽  
Brittle Fracture ◽  
Digital Camera ◽  
Calibration Method ◽  
Tensile Tests ◽  
Damage Effect ◽  
Fracture Mechanisms ◽  
Dynamic Surface ◽  
Hardening Mechanism

The main issue of wood is its sensitivity to Relative Humidity (RH) variations, affecting its dimensional stability, and thus leading to crack formations and propagations. In situ structural health monitoring campaigns imply the use of portable noninvasive techniques such as acoustic emission, used for real-time detection of energy released when cracks form and grow. This paper proposes a calibration method, i.e., acoustic emission, as an early warning tool for estimating the length of new formed cracks. The predictability of ductile and brittle fracture mechanisms based on acoustic emission features was investigated, as well as climate-induced damage effect, leading to a strain-hardening mechanism. Tensile tests were performed on specimens submitted to a 50% RH variation and coated with chemicals to limit moisture penetration through the radial surfaces. Samples were monitored for acoustic emission using a digital camera to individuate calibration curves that correlated the total emitted energy with the crack propagation, specifically during brittle fracture mechanism, since equations provide the energy to create a new surface as the crack propagates. The dynamic surface energy value was also evaluated and used to define a Locus of Equilibrium of the energy surface rate for crack initiation and arrest, as well as to experimentally demonstrate the proven fluctuation concept.

Use of Nanoparticles for the Development of High-Performance Nanoresins

2010 ◽  
Author(s):  
Vamshi M. Gudapati ◽  
Mehrdad N. Ghasemi-Nejhad
Keyword(s):  
Fracture Toughness ◽  
High Performance ◽  
Particle Concentration ◽  
Tensile Tests ◽  
Tensile Failure ◽  
Scanning Electron Micrographs ◽  
Sic Nanoparticles ◽  
Weight Percentage ◽  
Maximum Elevation ◽  
Local Plastic Deformation

In this study, a brittle epoxy resin has successfully been toughened by very small concentrations of SiC and diamond nanoparticles. The tensile stress-strain response (based on the ASTM tensile tests for polymers) and the fracture energy release rate, GIC, (based on the ASTM Single-Edge-Notched-Bending, SENB, tests for polymers) of neat and nano-reinforced epoxy were characterized over a range of nanoparticle concentrations. The maximum elevation of the fracture toughness, GIC, occurred at a very small particle concentration of about 0.2% by weight, for both diamond and SiC nanoparticles). This was also manifested as higher tensile failure stress and strain. The elevation of fracture toughness is most likely due to crack front trapping of the particles that promoted subsequent local plastic deformation. Scanning electron micrographs of the fracture surfaces for samples tested in tension and fracture showed the transition of epoxy behavior from brittle-to-ductile-to-brittle with increasing weight percentage of nanoparticles. At higher particle concentrations, flaky fracture surface was observed and the fracture toughness dropped, attaining values similar to the unreinforced polymer, which is attributed to agglomeration of the nanoparticles.

THERMODYNAMIC AND KINETIC ANALYSES OF SYNTHESIZING ZrB2@Al(OH)3–Y(OH)3 CORE–SHELL COMPOSITE PARTICLES

2007 ◽  
Vol 14 (01) ◽  
pp. 117-122 ◽  
Author(s):  
JIEGUANG SONG ◽  
LIANMENG ZHANG ◽  
JUNGUO LI ◽  
JIANRONG SONG
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Solubility Product ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Composite Particles ◽  
Core Shell ◽  
High Temperature Strength ◽  
Co Precipitation ◽  
Shell Composite

ZrB 2 has some excellent performances, but it is easily oxidized at high temperatures to impact the high-temperature strength, which restricts its applied range. To protect from the oxidization and improve the strength of ZrB 2 at high temperature, the surface of ZrB 2 particles is coated with the Al ( OH )3– Y ( OH )3 shell to synthesize ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles. Through the thermodynamic and kinetic analyses of the heterogeneous nucleation and homogeneous nucleation, the concentration product of precursor ion ( Y 3+ or Al 3+) and OH - (Qi) must be greater than the solubility product (K sp ), respectively; the conditions of Y 3+ and Al 3+ are reached to produce Al ( OH )3– Y ( OH )3 shell on the ZrB 2 surface between the Y 3+ line and the AlO 2- line. Through TEM and XRD analyses, ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles are successfully synthesized by the co-precipitation method, the shell layer quality is better at pH = 9, which established the foundation for preparing high-performance YAG / ZrB 2 and Al 2 O 3– YAG / ZrB 2 multiphase ceramic materials.

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