scholarly journals Iron-chromium-carbon-vanadium white cast irons: Microstructure and properties

2014 ◽  
Vol 68 (4) ◽  
pp. 413-427 ◽  
Author(s):  
Mirjana Filipovic
Keyword(s):  
Fracture Toughness ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Dynamic Fracture Toughness ◽  
M23c6 Carbide ◽  
Cast Irons ◽  
Repeated Impact ◽  
Secondary Carbides ◽  
The Matrix ◽  
Microstructure Parameters

The as-cast microstructure of Fe-Cr-C-V white irons consists of M7C3 and vanadium rich M6C5 carbides in austenitic matrix. Vanadium changed the microstructure parameters of phase present in the structure of these alloys, including volume fraction, size and morphology. The degree of martensitic transformation also depended on the content of vanadium in the alloy. The volume fraction of the carbide phase, carbide size and distribution has an important influence on the wear resistance of Fe-Cr-C-V white irons under low-stress abrasion conditions. However, the dynamic fracture toughness of Fe-Cr-C-V irons is determined mainly by the properties of the matrix. The austenite is more effective in this respect than martensite. Since the austenite in these alloys contained very fine M23C6 carbide particles, higher fracture toughness was attributed to a strengthening of the austenite during fracture. Besides, the secondary carbides which precipitate in the matrix regions also influence the abrasion behaviour. By increasing the matrix strength through a dispersion hardening effect, the fine secondary carbides can increase the mechanical support of the carbides. Deformation and appropriate strain hardening occur in the retained austenite of Fe-Cr-C-V alloys under repeated impact loading. The particles of precipitated M23C6 secondary carbides disturb dislocations movement and contribute to increase the effects of strain hardening in Fe-Cr-C-V white irons.

scholarly journals The effect of the subcritical heat treatment on the microstructure and properties of Fe-Cr-C-V alloys

2014 ◽  
Vol 20 (1) ◽  
pp. 1-14
Author(s):  
Mirjana Filipović ◽  
Željko Kamberović ◽  
Marija Korać
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Volume Fraction ◽  
Dynamic Fracture Toughness ◽  
Austenitic Matrix ◽  
Cast Irons ◽  
High Chromium ◽  
Eutectic Carbides ◽  
Matrix Microstructure ◽  
The Matrix

Experimental results indicate that the volume fraction of the carbide phase, carbide size and distribution had an important influence on the wear resistance of Fe-CrC-V alloys under low-stress abrasion conditions. Besides, the martensitic or martensiteaustenitic matrix microstructure more adequately reinforced the M7C3 eutectic carbides, minimizing cracking and removal during wear, than did the austenitic matrix. The secondary carbides which precipitate in the matrix regions of high chromium iron also influence the abrasion behaviour. The results of fracture toughness tests show that the dynamic fracture toughness in Fe-Cr-C-V white cast irons is determined mainly by the properties of the matrix. The high chromium iron containing 1.19 wt.% V in the as-cast condition, showed the greater dynamic fracture toughness when compared to other experimental alloys. The higher fracture toughness was attributed to strengthening during fracture, since very fine secondary carbide particles were present mainly in an austenitic matrix. In heat treated Fe-Cr-C-V alloys with varying contents of vanadium, lower Kid values were obtained, compared with as-cast alloys.

Loading Rate Effect on Translaminar Fracture Toughness of Hybrid Composite Laminate

2000 ◽  
Author(s):  
Paul Moy ◽  
Jerome Tzeng
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Glass Matrix ◽  
Small Volume ◽  
Loading Rate ◽  
Volume Fraction ◽  
Rate Effect ◽  
The Matrix ◽  
Small Volume Fraction ◽  
Matrix Property

Abstract Fracture toughness properties of composite laminates were evaluated at a loading rate commonly observed in ordinance applications. The laminates are composed of IM7 graphite and a small volume fraction of S2 glass plies to form a cross-ply laminate. Fracture toughness appears to be very rate sensitive if the crack growth perpendicular to the plane dominated by glass/matrix property. Experimental data shows a 30–40% increase of fracture toughness for various layup as the loading rate was increase by 1000 times. The specimens examined under microscopic indicates the strengthening might due to different failure mechanism in the matrix. In addition, there is no visible rate effect if the crack propagation is perpendicular to the graphite dominant plane.

scholarly journals Structural Investigations of Solidification and Heat Treatments Influence on High Alloyed Cast Irons Grades with Nb-V-Ti Additions

2009 ◽  
Vol 289-292 ◽  
pp. 77-86 ◽  
Author(s):  
Jacqueline Lecomte-Beckers ◽  
Jérôme Tchoufang Tchuindjang
Keyword(s):  
Phase Transformations ◽  
Volume Fraction ◽  
Raw Materials ◽  
Solidification Process ◽  
Heat Treatments ◽  
Hot Strip Mill ◽  
Cast Irons ◽  
Structural Investigations ◽  
Alloyed Cast ◽  
The Matrix

Two High Alloyed Cast Irons (HACI) were studied, both belonging to the Fe-C-Cr-Si-X system where X represented a strong carbide forming element. One of these alloys was obtained after adding Nb, V and Ti to the chemical composition of the other alloy. Raw materials originated from spun cast rolls for hot strip mill were submitted to different heat treatments routes, in order to study the influence of alloying elements on the microstructure. Both HACI grades contained a mixture of martensite and retained austenite matrix in the as-cast conditions and after quenching. Differential Thermal Analysis was carried out on the heat treated samples in order to determine the phase transformations occurring during re-melting and subsequent solidification sequence. Diffusionless transformations leading to various types of martensite were found in the matrix. Bulky NbC carbides precipitating at the beginning of the solidification process strongly influence the nature and the rate of the subsequent diffusional phase transformations, particularly for HACI grade with Nb, V and Ti additions. Quantitative metallography was done to determine graphite, NbC carbides, cementite and matrix volume fraction in HACI studied grades.

Climb-Enabled Discrete Dislocation Plasticity Analysis of the Deformation of a Particle Reinforced Composite

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
C. Ayas ◽  
L. C. P. Dautzenberg ◽  
M. G. D. Geers ◽  
V. S. Deshpande
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Dislocation Motion ◽  
Dislocation Climb ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Wall Structures ◽  
The Matrix

The shear deformation of a composite comprising elastic particles in a single crystal elastic–plastic matrix is analyzed using a discrete dislocation plasticity (DDP) framework wherein dislocation motion occurs via climb-assisted glide. The topology of the reinforcement is such that dislocations cannot continuously transverse the matrix by glide-only without encountering the particles that are impenetrable to dislocations. When dislocation motion is via glide-only, the shear stress versus strain response is strongly strain hardening with the hardening rate increasing with decreasing particle size for a fixed volume fraction of particles. This is due to the formation of dislocation pile-ups at the particle/matrix interfaces. The back stresses associated with these pile-ups result in a size effect and a strong Bauschinger effect. By contrast, when dislocation climb is permitted, the dislocation pile-ups break up by forming lower energy dislocation wall structures at the particle/matrix interfaces. This results in a significantly reduced size effect and reduced strain hardening. In fact, with increasing climb mobility an “inverse size” effect is also predicted where the strength decreases with decreasing particle size. Mass transport along the matrix/particle interface by dislocation climb causes this change in the response and also results in a reduction in the lattice rotations and density of geometrically necessary dislocations (GNDs) compared to the case where dislocation motion is by glide-only.

Characterization of Fracture Toughness of Hybrid MMCs the Short Fiber Reinforced Metal Matrix Composites

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1827-1832
Author(s):  
Moon Sik Han ◽  
Jung Il Song
Keyword(s):  
Fracture Toughness ◽  
Metal Matrix Composites ◽  
Dynamic Fracture ◽  
Metal Matrix ◽  
Matrix Alloy ◽  
Short Fiber ◽  
Dynamic Fracture Toughness ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
The Matrix

Evaluation of fracture toughness of short fiber reinforced metal matrix composites (MMCs) becomes important for the application as structural materials. Therefore, in this study static and dynamic fracture toughness of MMCs manufactured by squeeze casting process were investigated. A number of MMCs have been tested with various matrix alloys, volume fractions, and specifically types of reinforcements. It was found that static and dynamic fracture toughness of metal matrix composites was remarkably decreased by the addition of ceramic reinforcements. Dynamic fracture toughness slightly decreased compared with static fracture toughness because of the effect of dynamic velocity under impact loading. The toughness of ceramic reinforced MMCs is controlled by a complexity interaction between the matrix alloy and reinforcement. Important properties which influence toughness include the type of reinforcement (its physical form, size), volume fraction and combination of reinforcement, and the matrix alloy. And notch fracture toughness of MMCs for simple evaluation was also discussed.

The Effects of Material Properties on Crack Tip Constraint and CTOD Fracture Toughness for Commonly Used Pipelines Steels

2020 ◽  
Author(s):  
Yinhui Zhang ◽  
Jian Shuai
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Strain Hardening ◽  
Oil And Gas ◽  
Volume Fraction ◽  
Petroleum Industry ◽  
Void Volume Fraction ◽  
Void Volume ◽  
Strain Hardening Exponent ◽  
Material Parameters

Abstract As the main transportation carrier of oil and gas, pipelines play a very important role in the petroleum industry. When the crack-containing pipelines subjected to external loads, the cracks may propagate gradually, and result in serious failure eventually. Therefore, accurately obtaining the fracture toughness is very essential for the safety assessment of the crack-containing pipelines. However, the fracture toughness is not a material intrinsic parameter, but heavily depends on the constraint. To obtain the accurate relationship between the constraint and the fracture toughness for different materials, it is necessary to determine the effects of different material parameters on the change characteristics of the constraint and the fracture toughness. In this work, the commonly used pipelines steels are selected as the research materials. The SENB specimens and the complete Gurson model are used to conduct the simulation with ABAQUS. The material parameters analyzed include strain hardening exponent, yield strength and initial void volume fraction. The results show that for the thinner specimen, the higher strain hardening capacity will result in lower constraint. The higher strain hardening capacity will result in higher constraint for the thicker specimen. For the thinner specimen, the constraint is approximately the same for the materials with different yield strength. The constraint will decrease with the increase of yield strength for the thicker specimen. In the middle range of the thickness of specimen, higher initial void volume fraction will result in higher constraint. For the thicker and thinner specimen, the effect of initial void volume is very weak. As the increase of strain hardening capacity and yield strength, the decreasing degree of the fracture toughness becomes higher in the increasing process of the constraint. A higher initial void volume will result in a lower decreasing degree of the fracture toughness. All of the results indicate that the strain hardening capacity is the main factor affecting the constraint and the fracture toughness. The initial void volume also has a significant effect on the fracture toughness. For the relationship between the constraint and the fracture toughness, the main affecting factor is the strain hardening capacity.

scholarly journals Structure and Properties of Cast Iron DESIGNATED for Working Layer of Rolls

2015 ◽  
Vol 5 (1) ◽  
pp. 77 ◽  
Author(s):  
K. N. Vdovin ◽  
A. N. Zavalishchin ◽  
D. A. Gorlenko ◽  
N. A. Feoktistov
Keyword(s):  
Cast Iron ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Centrifugal Casting ◽  
Structure And Properties ◽  
Cast Irons ◽  
Metallic Base ◽  
Slow Cooling ◽  
Working Layer ◽  
Secondary Carbides

<p class="1Body">The formation of the structure and properties of cast irons designated for the working layer during solidification and subsequent tempering of Indefinite Chill Double Poured Centrifugal Casting Rolls (ICDP) has been studied.</p><p class="1Body">Graphitization of cast irons designated for the working layer of rolls occurs under isothermal conditions at high temperatures, which vary over the cross section and resulted from casting the roll core. At subsequent slow cooling, secondary carbides precipitate and austenite partially transforms into martensite; the resulting end structure consists of martensite and austenite metallic base (primary austenite dendrites) with 11.4 per cent of retained austenite, 26 per cent of eutectic and secondary carbides, and 2.6 per cent of flake graphite.<em> </em></p><p class="1Body">The amount of retained austenite in the metallic base of the cast structure of cast iron designated for the working layer, heated to 430 °C, decreases<strong> </strong>from 11.4 per cent to 3.2 per cent due to the partial transformation into bainite. The martensite tetragonality decreases due to the carbide precipitation; the existing excess phases grow and the new ones are formed; the total volume fraction of the carbide phase increases to 29.8 per cent and graphite to 3.7 per cent.</p>

Determination of the relationship between microstructure and constitutive behaviour of nodular cast iron with a unit cell model

2005 ◽  
Vol 40 (2) ◽  
pp. 107-116 ◽  
Author(s):  
L Collini ◽  
G Nicoletto
Keyword(s):  
Cast Iron ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Cell Model ◽  
Nodular Cast Iron ◽  
Unit Cell ◽  
Constitutive Law ◽  
Cast Irons ◽  
Present Contribution ◽  
The Matrix

Unit cell models have been proposed to predict the constitutive law and failure of ductile materials with complex microstructures, such as ferritic nodular cast iron and particulate metal matrix composites (PMMCs). The present contribution aims to extend this modelling approach to the prediction of the constitutive response of nodular cast iron with a mixed ferritic/pearlitic matrix. The finite element method is used within the framework of continuum mechanics to carry out the calculations. The effect of some microstructural features, such as graphite volume fraction and ferrite-pearlite ratio of the matrix, on the mechanical performance is determined. The computational results are compared to results obtained in a previous experimental activity on nodular cast irons.

scholarly journals Weldability and Damage Evaluations of Fresh-to-Aged Reformer Furnace Tubes

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 900
Author(s):  
Chengming Fuyang ◽  
Yang Zhou ◽  
Bing Shao ◽  
Tianyu Zhang ◽  
Xiaofeng Guo ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Welded Joint ◽  
Cast Alloy ◽  
Aging Treatment ◽  
Creep Process ◽  
M23c6 Carbide ◽  
Continuous Exposure ◽  
Damage Evaluation ◽  
Secondary Carbides ◽  
The Matrix

The microstructures and tensile properties of fresh and aged reformer furnace tubes and a fresh-to-aged welded joint were investigated to assess the weldability of fresh-to-aged reformer furnace tubes. Damage evaluation of the fresh-to-aged welded joint was also carried out using the modified Kachanov–Rabotnov model. The experimental results showed that M7C3 carbide transforms into M23C6 carbide and secondary carbides precipitate in the matrix after aging treatment. With continuous exposure, the interdendritic precipitates coalesced and coarsened and the number of secondary carbides reduced gradually. Microdefects were absent in the fresh-to-aged welded joint, and the tensile properties of the welded joint were close to the as-cast alloy, which confirms the weldability of fresh-to-aged furnace tubes. According to the results of the simulation, stress redistribution occurred during the creep process and the peak damage of the welded joint was located in the aged tube. The maximum damage of the fresh-to-aged welded joint reached 34.01% at 1.5 × 105 h.

Effect of the microstructure on the notched tensile strength of as-cast and austempered ductile cast irons

2012 ◽  
Vol 226 (9) ◽  
pp. 2214-2229 ◽  
Author(s):  
Ali Durmuş ◽  
Hakan Aydın ◽  
Mümin Tutar ◽  
Ali Bayram ◽  
Kurtuluş Yiğit
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Notch Root ◽  
Notch Sensitivity ◽  
Cast Irons ◽  
The Matrix ◽  
Notch Tensile Strength ◽  
The Difference ◽  
Notched Tensile Strength

In this study, the effect of microstructure on the mechanical properties of four types of ductile cast irons with different morphologies was investigated using circumferentially notched cylindrical specimens with different notch root radii. These cast irons were also austempered using the same austempering heat treatment to make a comparison with the as-cast samples. Characterization of the specimens has been carried out by means of microstructure, hardness, tensile properties, notch tensile strength, notch sensitivity, fracture toughness, and fractography. A mixture of ferrite and pearlite in the microstructure of cast irons gives rise to a material of the highest tensile strength, notch tensile strength, and fracture toughness properties with the intermediate ductility and notch sensitivity. A higher pearlite in the matrix of cast irons gives very important mechanical properties such as hardness and strength, but brittleness of the matrix andnotch sensitivity are greatly increased. Austempering significantly increased the mechanical properties and also reduced the difference between the mechanical properties of the cast irons. Austempered ferritic ductile irons exhibited the highest notch tensile strength and fracture toughness, and the high tensile strength and the intermediate ductility properties with the lowest notch sensitivity, whereas austempered pearlitic ductile irons had the lowest tensile strength, ductility, notch tensile strength, fracture toughness, and the intermediate notch sensitivity properties. The mechanical properties of the as-cast and austempered ductile irons have increased almost linearly with increase in the notch root radius.

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