Pub Date : 2016-12-09DOI: 10.7777/jkfs.2016.36.6.187
Heon-Joo Kim
The effects of scrap content on the impact and fatigue properties were investigated in AC4A alloy. The impact absorbed energy of as-cast specimens were 3.61, 3.56, 3.47, and 3.08 Joules, respectively, when scrap contents of the specimens were 0, 20, 35, and 50%. And, the corresponding energy levels of the T6 heat-treated condition were 3.66, 3.48, 3.25, and 2.96 Joule. In the same way, the fatigue strength values of the as-cast specimens were 53.2, 52.0, 48.4, and 43.8MPa, respectively, and the corresponding fatigue strengths of the T6 heat-treatment specimens were 85.4, 75.7, 60.6, and 51.2 MPa. Impact absorbed energy and fatigue strength decreased as scrap content of the specimen increased. It is assumed that impact absorbed energy decreased owing to the presence of oxide films, which act as branches of 2nd cracks; fatigue strength also decreased with decreased deflection of the fatigue crack path as the scrap content of the specimens increased.
{"title":"Effect of Scrap Content on the Impact Property and Fatigue Property of AC4A Alloy","authors":"Heon-Joo Kim","doi":"10.7777/jkfs.2016.36.6.187","DOIUrl":"https://doi.org/10.7777/jkfs.2016.36.6.187","url":null,"abstract":"The effects of scrap content on the impact and fatigue properties were investigated in AC4A alloy. The impact absorbed energy of as-cast specimens were 3.61, 3.56, 3.47, and 3.08 Joules, respectively, when scrap contents of the specimens were 0, 20, 35, and 50%. And, the corresponding energy levels of the T6 heat-treated condition were 3.66, 3.48, 3.25, and 2.96 Joule. In the same way, the fatigue strength values of the as-cast specimens were 53.2, 52.0, 48.4, and 43.8MPa, respectively, and the corresponding fatigue strengths of the T6 heat-treatment specimens were 85.4, 75.7, 60.6, and 51.2 MPa. Impact absorbed energy and fatigue strength decreased as scrap content of the specimen increased. It is assumed that impact absorbed energy decreased owing to the presence of oxide films, which act as branches of 2nd cracks; fatigue strength also decreased with decreased deflection of the fatigue crack path as the scrap content of the specimens increased.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"07 1","pages":"187-194"},"PeriodicalIF":0.0,"publicationDate":"2016-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85856988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-09DOI: 10.7777/JKFS.2016.36.6.202
Jeehoon Kim, Ji-tae Kim, Jin-Han Kim, Heung-Il Park, Sung-Gyoo Kim
The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the α phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nom-inal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of 703-781 N/mm 2 , elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.
{"title":"Effects of Iron and Silicon Additions on the Microstructures and Mechanical Properties of Aluminium Bronze","authors":"Jeehoon Kim, Ji-tae Kim, Jin-Han Kim, Heung-Il Park, Sung-Gyoo Kim","doi":"10.7777/JKFS.2016.36.6.202","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.6.202","url":null,"abstract":"The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the α phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nom-inal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of 703-781 N/mm 2 , elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"10 1","pages":"202-207"},"PeriodicalIF":0.0,"publicationDate":"2016-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77626843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-31DOI: 10.7777/JKFS.2016.36.5.147
Min-kyung Park, J. Cho, Seong-Hee Lee, C. Kim
Aluminum has been used as an alternative material for copper, due to its good electrical and thermal conductivities. However, small quantities of transition elements such as Ti and V affect the conductivities of aluminum. Therefore, in this study, the influence of B addition to reduce the effects of Ti and V on the conductivities of aluminum was investigated. Both the electrical and thermal conductivities of aluminum were improved with addition of B up to 0.05 wt%, while the conductivities were gradually reduced with an excess amount of B. SEM-EDS and XRD results exhibited that B reacted with Ti and V element to form diborides, such as TiB 2 and VB 2 phase, and those diborides tended to settle down to the bottom of the crucible because their densities were higher than that of aluminum melt. As a result, B reduced the deleterious effects of Ti and V, and the electrical and thermal conductivities of aluminum were improved.
{"title":"Effect of Boron on Electrical and Thermal Conductivities of Aluminum","authors":"Min-kyung Park, J. Cho, Seong-Hee Lee, C. Kim","doi":"10.7777/JKFS.2016.36.5.147","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.5.147","url":null,"abstract":"Aluminum has been used as an alternative material for copper, due to its good electrical and thermal conductivities. However, small quantities of transition elements such as Ti and V affect the conductivities of aluminum. Therefore, in this study, the influence of B addition to reduce the effects of Ti and V on the conductivities of aluminum was investigated. Both the electrical and thermal conductivities of aluminum were improved with addition of B up to 0.05 wt%, while the conductivities were gradually reduced with an excess amount of B. SEM-EDS and XRD results exhibited that B reacted with Ti and V element to form diborides, such as TiB 2 and VB 2 phase, and those diborides tended to settle down to the bottom of the crucible because their densities were higher than that of aluminum melt. As a result, B reduced the deleterious effects of Ti and V, and the electrical and thermal conductivities of aluminum were improved.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"10 1","pages":"147-152"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82321535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-31DOI: 10.7777/JKFS.2016.36.5.153
Jeong-Min Kim, Tae-Hyung Ha, K. Choe
The lost foam casting process was used to fabricate Al-Si-Mg cast specimens, and the effects of the chemical composition and process variables on the tensile properties and the mold filling ability were investigated. Some porosity formation was observed in thick sections of the casting and better tensile properties were obtained for thin sections, presumably because of their lower porosity and the higher cooling rate. Tensile properties were not clearly enhanced by grain refining treatment with Ti; however, the elon-gation was significantly improved by Sr modification of the Al-Si-Mg alloy. The mold filling distance was generally proportional to the pouring temperature of the melt, and the distance was also increased by the addition of Ti.
{"title":"Mechanical Properties and Mold Filling Capability of Al-Si-Mg Casting Alloy Fabricated by Lost Foam Casting Process","authors":"Jeong-Min Kim, Tae-Hyung Ha, K. Choe","doi":"10.7777/JKFS.2016.36.5.153","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.5.153","url":null,"abstract":"The lost foam casting process was used to fabricate Al-Si-Mg cast specimens, and the effects of the chemical composition and process variables on the tensile properties and the mold filling ability were investigated. Some porosity formation was observed in thick sections of the casting and better tensile properties were obtained for thin sections, presumably because of their lower porosity and the higher cooling rate. Tensile properties were not clearly enhanced by grain refining treatment with Ti; however, the elon-gation was significantly improved by Sr modification of the Al-Si-Mg alloy. The mold filling distance was generally proportional to the pouring temperature of the melt, and the distance was also increased by the addition of Ti.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"8 1","pages":"153-158"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76270832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-31DOI: 10.7777/JKFS.2016.36.5.167
J. Do, Insoo Kim, B. Choi, J. Jung, In-Yong Jung, C. Jo
The effect of various types of heat-treatment on the mechanical properties of cast Alloy 718 has been investigated. Cast Alloy 718 bars were subjected to ‘standard heat-treatment’_(SHT), ‘HIP (Hot Isostatic Pressing) heat-treatment’_(HHT), and ‘HIP-sim-ulated heat-treatment’_(HS). In the absence of long time high temperature heat-treatment, a small amount of Laves phase remained in the ‘SHT’ specimen, and needle shaped δ precipitated in the vicinity of the Laves phase. Due to the formation of the Laves and δ phases in the ‘SHT’ specimen, it exhibited lower tensile properties than those of the others_specimens. On the other hand, the Laves phase was completely dissolved into the matrix after ‘HHT’ and ‘HS’ treatments. It is known that isostatic pressure reduces the self-diffusion coefficient, because of the lower self-diffusivity under HIP conditions in the interdendritic region, Nb segregation and the high amount of γ ” precipitation that occurs. Due to the higher fraction of coarse γ ” phases, the ‘HHT’ treated Alloy 718 showed excellent tensile
{"title":"Effect of Heat-treatment on Microstructure and Tensile Properties in Cast Alloy 718","authors":"J. Do, Insoo Kim, B. Choi, J. Jung, In-Yong Jung, C. Jo","doi":"10.7777/JKFS.2016.36.5.167","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.5.167","url":null,"abstract":"The effect of various types of heat-treatment on the mechanical properties of cast Alloy 718 has been investigated. Cast Alloy 718 bars were subjected to ‘standard heat-treatment’_(SHT), ‘HIP (Hot Isostatic Pressing) heat-treatment’_(HHT), and ‘HIP-sim-ulated heat-treatment’_(HS). In the absence of long time high temperature heat-treatment, a small amount of Laves phase remained in the ‘SHT’ specimen, and needle shaped δ precipitated in the vicinity of the Laves phase. Due to the formation of the Laves and δ phases in the ‘SHT’ specimen, it exhibited lower tensile properties than those of the others_specimens. On the other hand, the Laves phase was completely dissolved into the matrix after ‘HHT’ and ‘HS’ treatments. It is known that isostatic pressure reduces the self-diffusion coefficient, because of the lower self-diffusivity under HIP conditions in the interdendritic region, Nb segregation and the high amount of γ ” precipitation that occurs. Due to the higher fraction of coarse γ ” phases, the ‘HHT’ treated Alloy 718 showed excellent tensile","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"55 1","pages":"167-173"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74433544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-31DOI: 10.7777/JKFS.2016.36.5.159
Insoo Kim, B. Choi, J. Jung, J. Do, In-Yong Jung, C. Jo
The microstructural evolution of a cast Ni base superalloy, IN738LC, has been investigated after long term exposure at several temperatures. Most of the fine secondary γ ' particles resolved after 2000 hour exposure at 816 o C. At higher temperatures of 871 o C and 927 o C, secondary γ ' resolved after 1000 hours of exposure, and cuboidal primary γ ' grew with exposure time. During the thermal exposure, σ phase formed at all tested temperatures, and η phase was observed around interdendritic regions due to carbide degeneration. The influence of microstructural evolution during thermal exposure on the mechanical properties has been analyzed. The effects of γ ' particle growth are more pronounced on the high temperature creep properties than on the room temperature tensile properties.
{"title":"Evolution of Microstructure and Mechanical Properties of a Ni Base Superalloy during Thermal Exposure","authors":"Insoo Kim, B. Choi, J. Jung, J. Do, In-Yong Jung, C. Jo","doi":"10.7777/JKFS.2016.36.5.159","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.5.159","url":null,"abstract":"The microstructural evolution of a cast Ni base superalloy, IN738LC, has been investigated after long term exposure at several temperatures. Most of the fine secondary γ ' particles resolved after 2000 hour exposure at 816 o C. At higher temperatures of 871 o C and 927 o C, secondary γ ' resolved after 1000 hours of exposure, and cuboidal primary γ ' grew with exposure time. During the thermal exposure, σ phase formed at all tested temperatures, and η phase was observed around interdendritic regions due to carbide degeneration. The influence of microstructural evolution during thermal exposure on the mechanical properties has been analyzed. The effects of γ ' particle growth are more pronounced on the high temperature creep properties than on the room temperature tensile properties.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"7 1","pages":"159-166"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85332753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-08-31DOI: 10.7777/JKFS.2016.36.4.117
In-Je Hwang, Young-Jig Kim, J. Jun
The effects of the Zn content on the microstructure and corrosion behavior in 1M NaCl solution were investigated in Mg(0~6)%Zn casting alloys. The MgZn phase was scarcely observed in the Mg-1%Zn alloy, while the Mg-(2~6)%Zn alloy consisted of α-(Mg) and MgZn phases. With an increase in the Zn content, the amount of the MgZn phase was gradually increased. Immersion and electrochemical corrosion tests indicated that the Mg-1%Zn alloy had the lowest corrosion rate among the alloys, and a further increase in the Zn content resulted in the deterioration of the corrosion resistance. Microstructural examinations of the corroded surfaces and EIS analyses of surface corrosion films revealed that the best corrosion resistance at 1%Zn was associated with the absence of MgZn phase particles in the microstructure and the contribution of Zn element to the formation of a protective film on the surface. A micro-galvanic effect by the MgZn particles led to the increased rate of corrosion at a higher Zn content.
{"title":"Corrosion behavior of Mg-(0~6)%Zn Casting Alloys in 1M NaCl Solution","authors":"In-Je Hwang, Young-Jig Kim, J. Jun","doi":"10.7777/JKFS.2016.36.4.117","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.4.117","url":null,"abstract":"The effects of the Zn content on the microstructure and corrosion behavior in 1M NaCl solution were investigated in Mg(0~6)%Zn casting alloys. The MgZn phase was scarcely observed in the Mg-1%Zn alloy, while the Mg-(2~6)%Zn alloy consisted of α-(Mg) and MgZn phases. With an increase in the Zn content, the amount of the MgZn phase was gradually increased. Immersion and electrochemical corrosion tests indicated that the Mg-1%Zn alloy had the lowest corrosion rate among the alloys, and a further increase in the Zn content resulted in the deterioration of the corrosion resistance. Microstructural examinations of the corroded surfaces and EIS analyses of surface corrosion films revealed that the best corrosion resistance at 1%Zn was associated with the absence of MgZn phase particles in the microstructure and the contribution of Zn element to the formation of a protective film on the surface. A micro-galvanic effect by the MgZn particles led to the increased rate of corrosion at a higher Zn content.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"67 1","pages":"117-125"},"PeriodicalIF":0.0,"publicationDate":"2016-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90377486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-06-30DOI: 10.7777/JKFS.2016.36.3.88
S. Kang, Kyeong-Seob Park, Eun-Ho Oh, Jung-Il Shim, Hee-Soo Kim
We investigated the effect of heat treatment on an ADC12 alloy produced using diecasting. The heat treatment used in this study was a typical T6 process: a solid solution treatment followed by an artificial aging treatment. As-cast specimens were solid-solution-treated at 500 o C and 530 o C for 1-16 hr, and aged at 160 o C and 180 o C for 1-8 hr. Microstructural changes in the alloy during the heat treatment were observed. Changes in mechanical properties of the alloy were measured using a micro-Vickers hardness tester. Finally, we determined the optimal heat treatment conditions for the diecast ADC12 alloy.
{"title":"Change of Mechanical Properties During Heat Treatment of Diecast ADC12 Alloy","authors":"S. Kang, Kyeong-Seob Park, Eun-Ho Oh, Jung-Il Shim, Hee-Soo Kim","doi":"10.7777/JKFS.2016.36.3.88","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.3.88","url":null,"abstract":"We investigated the effect of heat treatment on an ADC12 alloy produced using diecasting. The heat treatment used in this study was a typical T6 process: a solid solution treatment followed by an artificial aging treatment. As-cast specimens were solid-solution-treated at 500 o C and 530 o C for 1-16 hr, and aged at 160 o C and 180 o C for 1-8 hr. Microstructural changes in the alloy during the heat treatment were observed. Changes in mechanical properties of the alloy were measured using a micro-Vickers hardness tester. Finally, we determined the optimal heat treatment conditions for the diecast ADC12 alloy.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"98 1","pages":"88-94"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76099130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-06-30DOI: 10.7777/JKFS.2016.36.3.81
Gu Beom Jeong, I. Kim, J. Song, P. Shin, S. Hong
In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle α phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added Fe2O3 exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.
{"title":"Effect of Scrap Impurities on Microstructure and Mechanical Properties of Zr Alloys","authors":"Gu Beom Jeong, I. Kim, J. Song, P. Shin, S. Hong","doi":"10.7777/JKFS.2016.36.3.81","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.3.81","url":null,"abstract":"In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle α phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added Fe2O3 exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"25 1","pages":"81-87"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90984015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-30DOI: 10.7777/JKFS.2016.36.2.60
D. Kim, B. Kim, K. Park, I. K. Chang
In this study, comparison of corrosion properties of the Mg-1.5Ge-1Zn (GZ21) alloy and Mg-9Al-1Zn (AZ91) alloy were investigated. The studied alloys were fabricated by permanent mold casting method. And the potentiodynamic test, hydrogen evolution test, immersion test and A.C Impedance test were carried out in a 3.5% NaCl solution with pH7.2 at room temperature to measure the corrosion properties. The microstructure of GZ21 alloy was composed of α-Mg and Mg2Ge phases and AZ91 alloy was composed of α-Mg and Mg17Al12 phases. From the test results, the corrosion property was improved by adding Ge. It seemed that the corrosion mechanism was changed from galvanic corrosion (AZ91) to filiform corrosion (GZ21).
{"title":"Comparison of Electrochemical Corrosion Properties of Permanent Mold Casting GZ21 Alloy and AZ91 Alloy","authors":"D. Kim, B. Kim, K. Park, I. K. Chang","doi":"10.7777/JKFS.2016.36.2.60","DOIUrl":"https://doi.org/10.7777/JKFS.2016.36.2.60","url":null,"abstract":"In this study, comparison of corrosion properties of the Mg-1.5Ge-1Zn (GZ21) alloy and Mg-9Al-1Zn (AZ91) alloy were investigated. The studied alloys were fabricated by permanent mold casting method. And the potentiodynamic test, hydrogen evolution test, immersion test and A.C Impedance test were carried out in a 3.5% NaCl solution with pH7.2 at room temperature to measure the corrosion properties. The microstructure of GZ21 alloy was composed of α-Mg and Mg2Ge phases and AZ91 alloy was composed of α-Mg and Mg17Al12 phases. From the test results, the corrosion property was improved by adding Ge. It seemed that the corrosion mechanism was changed from galvanic corrosion (AZ91) to filiform corrosion (GZ21).","PeriodicalId":16318,"journal":{"name":"Journal of Korea Foundry Society","volume":"43 1","pages":"60-66"},"PeriodicalIF":0.0,"publicationDate":"2016-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84559277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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