• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.38-48
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• 1998

To apply the high chromium white cast irons for sliding parts of construction equipments, the wear characteristics of these alloys which have three kinds of microstructure(hypoeutectic, near-eutectic, hypereutectic) were investigated by dry sand/rubber wheel tester. Also, the effect of heat treatment was investigated for the same alloys. As result of the test, heat treatment have no effect on the wear characteristics. And, hypereutectic composition alloy has the highest wear resistance against SiO$_2$. Also after test, cracking was observed in eutectic and primary carbides of all materials tested. This phenomenon was important factor in the wear resistance.

• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.43-49
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• 1990

The influences of Cu and Mg addition on wear properties of SiC particulate reinforced Al-Si metal(alloy) matrix composites were investigated. Metal matrix composites were prepared by combination of compocasting and hot pressing techniques. The main results obtained are as follows : 1) The composite with Mg addition exhibits letter wear resistance than that with Cu addition. It is considered that Mg addition improved wettability of matal matrix composite by the strong segregation to the SiC / Al matrix interface. 2) After homogenization treatment, it was found that the interfacial segregation of Mg was predominant, while that of Cu was not detected. 3) The SiC / Al-11Si eutectic composite exhibits better wear resistance than the SiC / Al-6Si hypoeutectic composite does. 4) It seems that the increase in the amount of Mg addition affects on the uniform dispersion of SiC particulates, on the refinement of microstructure and on age hardening and these effects cause wear resistance improvement of composites.

• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1421-1425
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• 1996

Sintered Si3N4 and Inconel composed of Ni(58-63%) Cr(21-25%) Al(1-17%) Mn(<1%) fe(balance) were pressurelessly joined by using Ag-Cu-Ti brazing filler metal at 950℃ and 1200℃ under N2 gas atmosphere of 1atm and their interfacial structures were investigated. In case that the reaction temperature was low as 950℃ its interfacial structure was "Inconel metal/Ti-rich phase layer/brazing filler metal layer/Si3N4 " Ti used as reactive metal existed in between inconel steel and brazing metal and moved to the interface of between brazing filler metal nd Si3N4 according as reaction temperature increased up to 1200℃. The interfacial structure of inconel steel-Si3N4 reacted at 1200℃ was ' inconel metal/Ni-rich phase layer containing of Fe. Cr and Si/Cu-rich phase layer containing of Mn and Si/Si3N4 " Cr Mn, Ni and Fe diffused to the interface of between brazing filler metal and Si3N4 and reacted with Si3N4 The most reactive components of ingredients of inconel metal were Cr and Mn. On the other hand Ti added as reactive components to Ag-Cu eutectic segregated into Ni-rich phase layer,.

• Korean Journal of Metals and Materials
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• v.48 no.7
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• pp.589-597
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• 2010

In the present study, the effect of variation in alloying elements on the carbide formation behavior during casting and homogenization treatment of M2 high speed steels was investigated. M2 high speed steels of various compositions were produced by vacuum induction melting. Contents of C, Cr, W, Mo, and V were varied from the basic composition of 0.8C, 0.3Si, 0.2Mn, 4.0Cr, 6.0W, 5.0Mo, and 2.0V in weight percent. Homogenization treatment at $1150^{\circ}C$ for 1.5 hr followed by furnace cooling was performed on the ingots. Area fraction and chemical compositions of eutectic carbide in as-cast and homogenized ingots were analyzed. Area fraction of eutectic carbide appeared to be higher in the ingots with higher contents of alloying elements the area fraction of eutectic carbide also appeared to be higher on the surface regions than in the center regions of ingots. As a result of the homogenization treatment, $M_2C$ carbide, which was the primary eutectic carbide in the as-cast ingots, decomposed into thermodynamically stable carbides, MC and $M_6C$. The latter carbide was found to be the main one after homogenization. Fine carbides uniformly distributed in the matrix was found to be MC type carbide and coarsened by homogenization.

• Journal of Korea Foundry Society
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• v.33 no.2
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• pp.55-62
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• 2013

Effect of Fe and Mn contents on the castability of Al-4wt%Mg-0.9wt%Si system alloy has been studied. According to the analysis of cooling curve for Al-4wt%Mg-0.9wt%Si-0.3wt%Fe-0.3/0.5wt%Mn alloy, ${\alpha}-Al_{15}(Fe,Mn)_3Si_2$ and ${\beta}-Al_5FeSi$ phases crystallized above eutectic temperature of $Mg_2Si$. Therefore, these phases affected both the fluidity and shrinkage behaviors of the alloy during solidification. As Fe and Mn contents of Al-4wt%Mg-0.9wt%Si system alloy increased from 0.1 wt% to 0.4 wt% and from 0.3 wt% to 0.5 wt% respectively, the fluidity of the alloy decreased by 26% and 33%. When Fe content of the alloy increased from 0.1 wt% to 0.4 wt%, 23% decrease of macro shrinkage and 19% increase of micro shrinkage appeared. Similarly, Mn content of the alloy increased from 0.3 wt% to 0.5 wt%, 11% decrease of macro shrinkage and 14% increase of micro shrinkage appeared. Judging from the castability of the alloy, Al-4wt%Mg-0.9wt%Si alloy with low content of Fe and Mn, 0.1 wt% Fe and 0.3 wt% Mn, is recommendable.

• Journal of Korea Foundry Society
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• v.13 no.1
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• pp.94-101
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• 1993

The effects of strontium content as modifier on microstructure and mechanical properties were studied in Al-10%Si-0.3%Mg cast alloys. There were not big differences in the form of eutectic Si particle and its morphology depending on adding amount of strontium, but the alloy modified by 0.012%Sr had shown the higher values than the alloy modified 0.038%Sr in strength, elongation and impact value.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.46-47
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• 2004

The microstructure and mechanical properties of the hypereutectic prealloyed Al-Si powders prepared by the gas atomization process were described in this paper. With increasing the gas pressure of the atomization, the average powder size was decreased from about $145{\mu}m\;to\;80{\mu}m$. The primary eutectic Si particles were uniformly distributed in the Al matrix and their size varied in the range of $8-10{\mu}m$. The high densified specimens with above 96% of the theoretical density were fabricated the hot pressing process. The UTS mechanical properties of VN1 specimens were much higher than that of conventional hypoeutectic Al-Si alloys.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.66-71
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• 2008

Alumium alloys hot forging process are gaining increased acceptance in the automotive and electronic industries and hot forging is one of the most efficient manufacturing method for mass product parts. It has been investigated the microstructures and mechanical properties of Al-11.7Si-0.5Mg (KNT40-T6)alloy fabricated by hot forging process for development of connecting rod in this study. The microstructure of hot forged specimen was composed of eutectic structure of alumimum solid solution and $Mg_2Si$ precipitates. The tensile strength of solutionized Al-11.7Si-0.5Mg alloy was 217MPa. This alloy showed a good corrosion resistance using electrochemical polarization test.

• Journal of Korea Foundry Society
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• v.38 no.6
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• pp.111-120
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• 2018

In this study, the effects of two different casting methods (gravity casting and, diecasting) and various solid-solution conditions on the mechanical properties of ASC (Al-10.5wt%Si-1.75wt%Cu) and ALDC12 (Al-10.3wt%Si-1.72wt%Cu-0.76wt%Fe-0.28wt% Mn-0.32wt%Mg-0.9wt%Zn) alloys were investigated. A thermodynamic solidification analysis program (PANDAT) was used to predict the liquidus, solidus, and phases of the used alloys. In the results of an XRD analysis, ${\beta}$-AlFeSi peaks were observed only in the ALDC12 alloy regardless of the casting method or SST (solid-solution treatment) conditions. However, according to the results of a FE-SEM observation, both ${\theta}(Al_2Cu)$ and ${\beta}$-AlFeSi were found to exist besides ${\alpha}$-Al and eutectic Si in the gravity-casted ASC alloy at $500^{\circ}C$ after a SST of 120min. The ${\alpha}$-AlFeSi and ${\beta}$-AlFeSi phases including the eutectic phases were also found to exist in the ALDC12 alloy. The results of a microstructural observation and analyses by XRD, FE-SEM and EDS were in good agreement with the PANDAT results. The gravity-casted ALDC12 and ASC specimens showed the highest Y.S. and UTS values after aging for three hours at $180^{\circ}C$ after a SST at $500^{\circ}C$ for 30min. At longer solid-solution treatment times at $500^{\circ}C$ in the gravity-casted ALDC12 and ASC specimens, the elongations of the ASC alloys increased, whereas they decreased slightly in the ALDC12 alloys.

• Journal of Korea Foundry Society
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• v.17 no.6
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• pp.585-591
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• 1997

Hyper-eutectic Al-17.5wt%Si alloy bars of 25 mm in diameter were produced by horizontal continuous casting process. Effect of both casting speed and primary Si refiner (AlCuP) on microstructure and mechanical properties of the alloy have been investigated. With increasing a weight fraction of AlCuP, the average primary Si size decreased down to $20 {\mu}m$. On the contrary, there was no notable changes of microstructure and primary Si size according to the casting speed in the experimental range of this study, indicating that the cooling rate should be increased to optimize and refine microstructure and primary Si size. The experimental results including hardness, tensile strength and wear resistance tests of the processed alloy bars showed a good possibility to develop the high performance wear resistant Al-Si alloy.