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Mehmet Erdogan - One of the best experts on this subject based on the ideXlab platform.
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The Evaluation of Structure - Property Relationships in the Dual Matrix Ductile Iron by Magnetic Barkhausen Noise Analysis
2020Co-Authors: Melika Ozer, Mehmet ErdoganAbstract:Structure-property relationships in ferritic ductile iron with a Dual-Matrix (ferrite, martensite) structure were evaluated by Magnetic Barkhausen Noise (MBN) analysis. Specimens were partially austenitised in the ferrite-austenite region at 795°C and 815°C for 20 minutes, and then quenched in 100oC-oil to obtain different phase contents. The specimens were subjected to tempering at 500oC for 1 and 3 h. The results showed that the volume fraction of phases can be controlled to modify the mechanical properties, and any change in the microstructure can be monitored by MBN.
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Comparison of abrasive wear behavior of ductile iron with different Dual Matrix structures
Wear, 2010Co-Authors: Y Sahin, Volkan Kilicli, Melika Ozer, Mehmet ErdoganAbstract:Abstract Abrasive wear behavior of ductile irons with different Dual Matrix structures has been investigated. In order to obtain ductile irons with different Dual Matrix structures an unalloyed ductile iron specimens were austenitized in the two-phase region (α + γ) at various temperature (795 °C and 815 °C) and then rapidly transferred to a salt bath held at the 365 °C for austempering for 30, 90 and 120 min. Some specimens were quenched from same intercritical austenitizing temperatures and tempered at 550 °C for 60 and 300 min. Some specimens were also conventionally austempered and/or quenched from 900 °C for comparison. Experimental results showed that, the tensile strength increased and ductility decreased with increasing martensite volume fraction in the specimen with martensite Dual Matrix structure. By increasing the tempering time, the yield and UTS decreased and ductility increased. In addition, the specimens with ausferrite Dual Matrix structures exhibited much greater ductility than conventionally austempered ones. The tensile strength increased while ductility decreased with increasing ausferrite volume fraction. Furthermore in all austenitized specimens, the abrasive weight loss of austempered specimens (A series) was lower than those of quenched specimens (Q series) irrespective of all loads due to increased AFVFs and total elongation. It was shown that wear loss of both tested materials in abrasive wear was proportional to the applied load. However, there was a decreasing trend in the weight loss of the A795 with Dual Matrix structure austempered for 30 and 90 min with increasing load. The reason was because of the fact that the specimen surface was work hardened with cutting efficiency of the abrasive reduced through clogging, and attrition jointly leading to less weight loss. Moreover, increasing the austempering time caused more ductile ausferritic structure to displace hard martensite. In all austempered samples, the abrasive weight loss increased with increasing the austempering time. As for the case of Q samples, the abrasive weight loss increased more or less linearly with load since an increase in the applied load might increase the contact stress. Among the Q samples, the highest weight loss was obtained for the Q795-300, Q815-300 sample because of lower martensite volume fraction, but the lowest weight loss was observed for the Q900 sample due to the highest martensite volume fraction. For Q900 samples, the amount of fracture of the abrasives was found to be increase with the harder specimen, and it may have contributed somewhat to the increased wear. Furthermore, microchips were dominant wear mechanism by cutting mode for higher ductile materials while micro-ploughing was predominant wear for harder materials, but wear also occurred by combinations of ploughing and embedding particles into the surface for Q samples. Cross-section examination by SEM through the wear surfaces revealed that a more smoother surface was observed for the A795 sample than that of the Q795 sample. However, a more rougher surface was observed for the A900-120 sample than that of the Q900 sample.
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The Nature of the Tensile Fracture in Austempered Ductile Iron with Dual Matrix Microstructure
Journal of Materials Engineering and Performance, 2009Co-Authors: Volkan Kilicli, Mehmet ErdoganAbstract:The tensile fracture characteristics of austempered ductile irons with Dual Matrix structures and different ausferrite volume fractions have been studied for an unalloyed ductile cast iron containing (in wt.%) 3.50 C, 2.63 Si, 0.318 Mn, and 0.047 Mg. Specimens were intercritically austenitized (partially austenitized) in two phase region (α + γ) at various temperatures for 20 min and then quenched into a salt bath held at austempering temperature of 365 °C for various times and then air cooled to room temperature to obtain various ausferrite volume fractions. Conventionally austempered specimens with fully ausferritic Matrix and unalloyed as-cast specimens having fully ferritic structures were also tested for comparison. In Dual Matrix structures, results showed that the volume fraction of proeutectoid ferrite, new (epitaxial) ferrite, and ausferrite [bainitic ferrite + high-carbon austenite (stabilized or transformed austenite)] can be controlled to influence the strength and ductility. Generally, microvoids nucleation is initiated at the interface between the graphite nodules and the surrounding ferritic structure and at the grain boundary junctions in the fully ferritic microstructure. Debonding of the graphite nodules from the surrounding Matrix structure was evident. The continuity of the ausferritic structure along the intercellular boundaries plays an important role in determining the fracture behavior of austempered ductile iron with different ausferrite volume fractions. The different fracture mechanisms correspond to the different levels of ausferrite volume fractions. With increasing continuity of the ausferritic structure, fracture pattern changed from ductile to moderate ductile nature. On the other hand, in the conventionally austempered samples with a fully ausferritic structure, the fracture mode was a mixture of quasi-cleavage and a dimple pattern. Microvoid coalescence was the dominant form of fracture in all structures.
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Effect of martensite volume fraction and tempering time on abrasive wear of ferritic ductile iron with Dual Matrix
Wear, 2008Co-Authors: Y Sahin, Mehmet Erdogan, M. CerahAbstract:Abstract The effect of martensite volume fraction (MVF) and tempering time on the abrasive wear of ferritic ductile iron with a Dual Matrix structure (DMS) was investigated. Specimens were partially austenitized in the two-phase region (α + γ) at temperatures of 795 and 815 °C for 20 min and then quenched in oil held at 100 °C to obtain different MVF. The specimens were subjected to tempering at a temperature of 500 °C for 1 and 5 h. Some specimens were also conventionally heat-treated (austenitized at 900 °C and then quenched + tempered) for comparison. Samples were tested for tensile strength, ductility and abrasive wear. The results showed that weight loss resistance and strength increased and ductility decreased with increasing MVF. At constant MVF (∼25 or 62%), weight loss increased with increasing tempering time. The lowest weight loss was obtained for the conventionally heat-treated sample having ∼90% MFV, while the highest weight loss was observed for the sample having ∼25% MFV. Moreover, the weight loss increased with increased applied load for all tested samples. Abrasive wear was predominant for the conventionally heat-treated sample while adhesive wear was observed for the Dual Matrix structure, but only slight changes occurred with increased tempering time.
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Investigation of the Variations in Microstructure and Mechanical Properties of Dual-Matrix Ductile Iron by Magnetic Barkhausen Noise Analysis
Research in Nondestructive Evaluation, 2008Co-Authors: Melika Ozer, Mehmet ErdoganAbstract:The variations in the microstructure and tensile properties of Dual-Matrix ductile irons have been investigated non-destructively by Magnetic Barkhausen Noise (MBN) method. Specimens have been intercritically austenitised at 795°C and 815°C for 20 minutes, and then oil-quenched to obtain different martensite volume fractions. Two specimens, namely as-cast and oil-quenched from 900°C, were prepared for comparison purpose. To investigate the effect of tempering, some specimens were tempered at 500°C for 1 h and 3 h. The results showed that there is a good correlation between MBN response and variations in microstructure and mechanical properties. The volume fraction of martensite can be controlled to modify the mechanical properties, and all changes in the microstructure can be nondestructively monitored by MBN.
M Taher - One of the best experts on this subject based on the ideXlab platform.
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properties of single and Dual Matrix aluminum carbon nanotube composites processed via spark plasma extrusion spe
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: K. Morsi, Amal M.k. Esawi, P Borah, S Lanka, A Sayed, M TaherAbstract:Abstract The interest in carbon nanotube (CNT) aluminum composites has been growing significantly over the past decade. Most work has focused on the generation of composite materials with homogeneously dispersed carbon nanotubes. On the other hand, the Dual Matrix composite microstructural design, where the Matrix is selectively reinforced in localized regions within the microstructure separated by ductile unreinforced Matrix, may present significant benefits. Primarily these benefits include an ability to tailor the properties of the final composite which may give rise to controlled properties and enhanced formability. This paper discusses Dual- and single-Matrix CNT–Al composites and milled aluminum processed via Spark Plasma Extrusion (SPE) and discusses the effect of the microstructural design on the mechanical properties.
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Properties of single and Dual Matrix aluminum–carbon nanotube composites processed via spark plasma extrusion (SPE)
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Khaled Morsi, Amal M.k. Esawi, P Borah, S Lanka, A Sayed, M TaherAbstract:Abstract The interest in carbon nanotube (CNT) aluminum composites has been growing significantly over the past decade. Most work has focused on the generation of composite materials with homogeneously dispersed carbon nanotubes. On the other hand, the Dual Matrix composite microstructural design, where the Matrix is selectively reinforced in localized regions within the microstructure separated by ductile unreinforced Matrix, may present significant benefits. Primarily these benefits include an ability to tailor the properties of the final composite which may give rise to controlled properties and enhanced formability. This paper discusses Dual- and single-Matrix CNT–Al composites and milled aluminum processed via Spark Plasma Extrusion (SPE) and discusses the effect of the microstructural design on the mechanical properties.
Joung-man Park - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of interfacial properties of atmospheric pressure plasma-treated CNT-phenolic composites by Dual Matrix fragmentation and acoustic emission tests
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Zuo Jia Wang, Ga Young Gu, Dong-jun Kwon, K. Lawrence Devries, Jong Kyoo Park, Joung-man ParkAbstract:Abstract A novel process of atmospheric pressure plasma treatment was performed, on powdered carbon nanotube (CNT) in water, to modify reinforcing effects and interfacial adhesion in carbon fiber reinforced CNT-phenolic composites. The change in chemical functional groups, as result of the plasma-treatment, was analyzed using Fourier transform infrared (FT-IR) spectroscopy. A significant enhancement in the wettability of plasma-treated CNT was also confirmed by static contact angle measurements. The advancing contact angle indicated a change in the surface from hydrophobic to hydrophilic. The interfacial adhesion between the carbon fibers and the plasma-treated CNT-phenolic Matrix also improved, as evidenced by an increase in the apparent modulus. Due to the brittle nature of the phenolic Matrix, Dual Matrix composites (DMC) were used in a modified fragmentation test. The different microfailure modes (phenolic Matrix cracking and carbon fiber breaking) were investigated by acoustic emission and electrical resistance measurements.
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Evaluation of interfacial properties of atmospheric pressure plasma-treated CNT-phenolic composites by Dual Matrix fragmentation and acoustic emission tests
Composites Part A: Applied Science and Manufacturing, 2013Co-Authors: Zuo Jia Wang, Ga Young Gu, Woo Il Lee, Dong-jun Kwon, K. Lawrence Devries, Jong Kyoo Park, Joung-man ParkAbstract:A novel process of atmospheric pressure plasma treatment was performed, on powdered carbon nano-tube (CNT) in water, to modify reinforcing effects and interfacial adhesion in carbon fiber reinforced CNT-phenolic composites. The change in chemical functional groups, as result of the plasma-treatment, was analyzed using Fourier transform infrared (FT-IR) spectroscopy. A significant enhancement in the wettability of plasma-treated CNT was also confirmed by static contact angle measurements. The advancing contact angle indicated a change in the surface from hydrophobic to hydrophilic. The interfacial adhesion between the carbon fibers and the plasma-treated CNT-phenolic Matrix also improved, as evidenced by an increase in the apparent modulus. Due to the brittle nature of the phenolic Matrix, Dual Matrix composites (DMC) were used in a modified fragmentation test. The different microfailure modes (phenolic Matrix cracking and carbon fiber breaking) were investigated by acoustic emission and electrical resistance measurements. ?? 2012 Elsevier Ltd. All rights reserved.
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Interfacial properties of glass fiber/brittle‐ductile Dual‐Matrix composites using micromechanical techniques and acoustic emission
Polymer Composites, 1999Co-Authors: Joung-man Park, Dong-woo Shin, Dong-jin YoonAbstract:The interfacial adhesion and microfailure modes of glass fiber-reinforced brittle unsaturated polyester/modified epoxy composites were investigated via micromechanical techniques and acoustic emission (AE). Various silane coupling agents caused different degrees of interfacial adhesion and subsequent microfailure modes. In the brittle Matrix layer, the number of Matrix fragments was significantly influenced by the type of silance coupling agents. The more cracks, the higher the interfacial adhesion under both dry and wet conditions. This is attributed to the chemical and hydrogen bondings in two interphases. The results obtained from microdroplet and fragmentation tests were correlated by associating with the AE technique. The sequential occurrence of mainly three groups of AE were as follows: the first group originated mainly from brittle Matrix cracking. The second and the third groups resulted in fiber breakage and ductile Matrix cracking and debonding. For Dual-Matrix specimens the micromechanical tests provide reliable information with regard to the interfacial adhesion and characterize the microfailure modes when combined with the AE technique.
Zuo Jia Wang - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of interfacial properties of atmospheric pressure plasma-treated CNT-phenolic composites by Dual Matrix fragmentation and acoustic emission tests
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Zuo Jia Wang, Ga Young Gu, Dong-jun Kwon, K. Lawrence Devries, Jong Kyoo Park, Joung-man ParkAbstract:Abstract A novel process of atmospheric pressure plasma treatment was performed, on powdered carbon nanotube (CNT) in water, to modify reinforcing effects and interfacial adhesion in carbon fiber reinforced CNT-phenolic composites. The change in chemical functional groups, as result of the plasma-treatment, was analyzed using Fourier transform infrared (FT-IR) spectroscopy. A significant enhancement in the wettability of plasma-treated CNT was also confirmed by static contact angle measurements. The advancing contact angle indicated a change in the surface from hydrophobic to hydrophilic. The interfacial adhesion between the carbon fibers and the plasma-treated CNT-phenolic Matrix also improved, as evidenced by an increase in the apparent modulus. Due to the brittle nature of the phenolic Matrix, Dual Matrix composites (DMC) were used in a modified fragmentation test. The different microfailure modes (phenolic Matrix cracking and carbon fiber breaking) were investigated by acoustic emission and electrical resistance measurements.
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Evaluation of interfacial properties of atmospheric pressure plasma-treated CNT-phenolic composites by Dual Matrix fragmentation and acoustic emission tests
Composites Part A: Applied Science and Manufacturing, 2013Co-Authors: Zuo Jia Wang, Ga Young Gu, Woo Il Lee, Dong-jun Kwon, K. Lawrence Devries, Jong Kyoo Park, Joung-man ParkAbstract:A novel process of atmospheric pressure plasma treatment was performed, on powdered carbon nano-tube (CNT) in water, to modify reinforcing effects and interfacial adhesion in carbon fiber reinforced CNT-phenolic composites. The change in chemical functional groups, as result of the plasma-treatment, was analyzed using Fourier transform infrared (FT-IR) spectroscopy. A significant enhancement in the wettability of plasma-treated CNT was also confirmed by static contact angle measurements. The advancing contact angle indicated a change in the surface from hydrophobic to hydrophilic. The interfacial adhesion between the carbon fibers and the plasma-treated CNT-phenolic Matrix also improved, as evidenced by an increase in the apparent modulus. Due to the brittle nature of the phenolic Matrix, Dual Matrix composites (DMC) were used in a modified fragmentation test. The different microfailure modes (phenolic Matrix cracking and carbon fiber breaking) were investigated by acoustic emission and electrical resistance measurements. ?? 2012 Elsevier Ltd. All rights reserved.
Volkan Kilicli - One of the best experts on this subject based on the ideXlab platform.
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Comparison of abrasive wear behavior of ductile iron with different Dual Matrix structures
Wear, 2010Co-Authors: Y Sahin, Volkan Kilicli, Melika Ozer, Mehmet ErdoganAbstract:Abstract Abrasive wear behavior of ductile irons with different Dual Matrix structures has been investigated. In order to obtain ductile irons with different Dual Matrix structures an unalloyed ductile iron specimens were austenitized in the two-phase region (α + γ) at various temperature (795 °C and 815 °C) and then rapidly transferred to a salt bath held at the 365 °C for austempering for 30, 90 and 120 min. Some specimens were quenched from same intercritical austenitizing temperatures and tempered at 550 °C for 60 and 300 min. Some specimens were also conventionally austempered and/or quenched from 900 °C for comparison. Experimental results showed that, the tensile strength increased and ductility decreased with increasing martensite volume fraction in the specimen with martensite Dual Matrix structure. By increasing the tempering time, the yield and UTS decreased and ductility increased. In addition, the specimens with ausferrite Dual Matrix structures exhibited much greater ductility than conventionally austempered ones. The tensile strength increased while ductility decreased with increasing ausferrite volume fraction. Furthermore in all austenitized specimens, the abrasive weight loss of austempered specimens (A series) was lower than those of quenched specimens (Q series) irrespective of all loads due to increased AFVFs and total elongation. It was shown that wear loss of both tested materials in abrasive wear was proportional to the applied load. However, there was a decreasing trend in the weight loss of the A795 with Dual Matrix structure austempered for 30 and 90 min with increasing load. The reason was because of the fact that the specimen surface was work hardened with cutting efficiency of the abrasive reduced through clogging, and attrition jointly leading to less weight loss. Moreover, increasing the austempering time caused more ductile ausferritic structure to displace hard martensite. In all austempered samples, the abrasive weight loss increased with increasing the austempering time. As for the case of Q samples, the abrasive weight loss increased more or less linearly with load since an increase in the applied load might increase the contact stress. Among the Q samples, the highest weight loss was obtained for the Q795-300, Q815-300 sample because of lower martensite volume fraction, but the lowest weight loss was observed for the Q900 sample due to the highest martensite volume fraction. For Q900 samples, the amount of fracture of the abrasives was found to be increase with the harder specimen, and it may have contributed somewhat to the increased wear. Furthermore, microchips were dominant wear mechanism by cutting mode for higher ductile materials while micro-ploughing was predominant wear for harder materials, but wear also occurred by combinations of ploughing and embedding particles into the surface for Q samples. Cross-section examination by SEM through the wear surfaces revealed that a more smoother surface was observed for the A795 sample than that of the Q795 sample. However, a more rougher surface was observed for the A900-120 sample than that of the Q900 sample.
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The Nature of the Tensile Fracture in Austempered Ductile Iron with Dual Matrix Microstructure
Journal of Materials Engineering and Performance, 2009Co-Authors: Volkan Kilicli, Mehmet ErdoganAbstract:The tensile fracture characteristics of austempered ductile irons with Dual Matrix structures and different ausferrite volume fractions have been studied for an unalloyed ductile cast iron containing (in wt.%) 3.50 C, 2.63 Si, 0.318 Mn, and 0.047 Mg. Specimens were intercritically austenitized (partially austenitized) in two phase region (α + γ) at various temperatures for 20 min and then quenched into a salt bath held at austempering temperature of 365 °C for various times and then air cooled to room temperature to obtain various ausferrite volume fractions. Conventionally austempered specimens with fully ausferritic Matrix and unalloyed as-cast specimens having fully ferritic structures were also tested for comparison. In Dual Matrix structures, results showed that the volume fraction of proeutectoid ferrite, new (epitaxial) ferrite, and ausferrite [bainitic ferrite + high-carbon austenite (stabilized or transformed austenite)] can be controlled to influence the strength and ductility. Generally, microvoids nucleation is initiated at the interface between the graphite nodules and the surrounding ferritic structure and at the grain boundary junctions in the fully ferritic microstructure. Debonding of the graphite nodules from the surrounding Matrix structure was evident. The continuity of the ausferritic structure along the intercellular boundaries plays an important role in determining the fracture behavior of austempered ductile iron with different ausferrite volume fractions. The different fracture mechanisms correspond to the different levels of ausferrite volume fractions. With increasing continuity of the ausferritic structure, fracture pattern changed from ductile to moderate ductile nature. On the other hand, in the conventionally austempered samples with a fully ausferritic structure, the fracture mode was a mixture of quasi-cleavage and a dimple pattern. Microvoid coalescence was the dominant form of fracture in all structures.
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Effect of ausferrite volume fraction and morphology on tensile properties of partially austenitised and austempered ductile irons with Dual Matrix structures
International Journal of Cast Metals Research, 2007Co-Authors: Volkan Kilicli, Mehmet ErdoganAbstract:Abstract In the present study, an unalloyed ductile iron containing 3·50%C, 2·63%Si, 0·318%Mn and 0·047%Mg was intercritically austenitised (partially austenitised) in the two phase region (α + γ) at temperatures of 795 and 815°C for 20 min, and then was quenched into a salt bath held at an austempering temperature of 365°C for various times to obtain various ausferrite volume fractions. Fine and coarse Dual Matrix structures were obtained from the two different starting conditions. Some specimens were also conventionally austempered from 900°C for comparison. Results showed that a structure having proeutectoid ferrite plus ausferrite (bainitic ferrite + high carbon retained or stabilised austenite) was developed. The phase previously described as new ferrite (also called epitaxial ferrite) was observed to form following heat treatment only in specimens with coarse austenite dispersion after austempering from the (α + γ) temperature range. It was observed that the parent austenite dispersion present at th...
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The Strain-Hardening Behavior of Partially Austenitized and the Austempered Ductile Irons with Dual Matrix Structures
Journal of Materials Engineering and Performance, 2007Co-Authors: Volkan Kilicli, Mehmet ErdoganAbstract:In the current study, an unalloyed ductile iron containing 3.50 C wt.%, 2.63 Si wt.%, 0.318 Mn wt.%, and 0.047 Mg wt.% was intercritically austenitized (partially austenitized) in two-phase regions (α + γ) at different temperatures for 20 min and then was quenched into salt bath held at austempering temperature of 365 °C for various times to obtain different ausferrite plus proeutectoid ferrite volume fractions. Fine and coarse Dual Matrix structures (DMS) were obtained from two different starting conditions. Some specimens were also conventionally austempered from 900 °C for comparison. The results showed that a structure having proeutectoid ferrite plus ausferrite (bainitic ferrite + high-carbon austenite (retained or stabilized austenite)) has been developed. Both of the specimens with ∼75% ausferrite volume fraction (coarse structure) and the specimen with ∼82% ausferrite volume fraction (fine structure) exhibited the best combination of high strength and ductility compared to the pearlitic grades, but their ductility is slightly lower than the ferritic grades. These materials also satisfy the requirements for the strength of the quenched and tempered grades and their ductility is superior to this grade. The correlation between the strain-hardening rates of the various austempered ductile iron (ADI) with DMS and conventionally heat-treated ADI microstructures as a function of strain was conducted by inspection of the respective tensile curves. For this purpose, the Crussard-Jaoul (C-J) analysis was employed. The test results also indicate that strain-hardening behavior of ADI with Dual Matrix is influenced by the variations in the volume fractions of the phases, and their morphologies, the degree of ausferrite connectivity and the interaction intensities between the carbon atoms and the dislocations in the Matrix. The ADI with DMS generally exhibited low strain-hardening rates compared to the conventionally ADI.
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wear behavior of austempered ductile irons with Dual Matrix structures
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Y Sahin, Mehmet Erdogan, Volkan KilicliAbstract:Abstract An unalloyed ductile iron containing 3.42 C wt.%, 2.63 Si wt.% and 0.318 Mn wt.% was intercritically austenitized in two-phase region (α + γ) at various temperatures of 795 °C, and 815 °C for 20 min and then quenched into salt bath held at austempering temperature of 365 °C for various times to obtain austempered ductile iron (ADI) with different ausferrite volume fractions distributed in soft proeutectoid ferrite Matrix. Some samples were also conventionally austempered for comparison reason. For austempered samples, the tensile strength and hardness decreased with increasing the austempering time, whereas the elongation increased considerably. In addition, the abrasive wear behavior of as cast and ADI's with Dual Matrix structure was studied under different loads without lubrication. It was found that the wear resistance of ADI with Dual Matrix structure was superior to that of as cast iron. Among the austempered samples, the lowest weight loss was observed for conventionally austempered samples with its wholly ausferritic structure throughout the specimen while the highest weight loss was obtained for the samples having the lowest ausferrite volume fractions in those samples with Dual Matrix structures. Moreover, wear resistance increased with increasing ausferrite volume fraction and decreasing austempering time in all tested samples.
