• 한국주조공학회지
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• 제35권1호
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• pp.8-14
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• 2015

Variations of nickel contents and microstructures in molten magnesium alloys on the addition of aluminum, zirconium, and manganese have been investigated. Specimens were prepared by melting under $SF_6$ and $CO_2$ atmosphere and casting into a disc of 29 mm diameter with 7~10 mm thickness from the melt acquired at the top of crucible. Before casting, the molten metal was stirred for 3 minutes after each addition of alloying elements and maintained for 30 minutes for settling down. Results showed that zirconium did not significantly affect the content of nickel while aluminum remarkably reduced it by forming $Al_3Ni_2$ phase. When manganese are added to Mg-1wt%Ni alloy along with aluminum, both elements remarkably reduced the content of nickel. The addition of 1.5 wt% manganese to Mg-1wt%Ni alloy containing aluminum further reduced the content of nickel by more than 30%, during which an additional intermetallic phase $Al_{10}Mn_3Ni$ was precipitated in the molten magnesium.

• Corrosion Science and Technology
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• 제21권4호
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• pp.290-299
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• 2022

Anodizing is an electrochemical surface treatment method conferring corrosion resistance and durability by forming a thick anodization film on the metal surface. Aluminum has a long service life and high thermal conductivity and formability, as well as excellent corrosion resistance. Aluminum 3003 alloy has improved formability, strength, and corrosion resistance due to the addition of a small amount of manganese. However, corrosion occurs in seawater and environments polluted with corrosion-inducing substances, which reduce corrosion resistance. Therefore, it is necessary to artificially form a thick anodized film to improve corrosion resistance. In this study, the anodization treatment time was 4 minutes, and voltages of 10 V, 20 V, 30 V, 40 V, 50 V, 60 V, 70 V, 80 V, 90 V, and 100 V were applied. The thickness and pore size of the oxide film increased according to the applied voltage. A barrier film was formed under voltage conditions from 10 V to 50 V, and a porous film was formed under voltage conditions from 60 V to 100 V. After anodizing, coating was applied. Wettability and corrosion resistance were observed before and after coating according to the surface shape and thickness of the oxide film.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.71-77
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• 2013

알루미늄 테르밋 반응의 환원제로서 알루미늄 분말은 200 메쉬 이하의 미분이 필요하나, 알루미늄의 높은 인성과 분말 제조비 때문에 경제적으로 용이하지 않다. 그러므로 $Mn_3O_4$ 분진 환원용 알루미늄 미분의 제조 코스트를 낮추기 위해, 알루미늄 합금분말의 제특성이 검토되었다. 망간을 다량 함유한 알루미늄 합금괴는 취성이 큰 금속간 화합물을 함유하고 있기 때문에 쉽게 파쇄할 수 있다. 또 망간은 망간 합금철의 주성분이다. Al-15%Mn 합금분말을 기계적 파쇄법으로 저렴하게 제조할 수 있다. Al 분말 대신에 Al-15%Mn 합금분말을 사용한 테르밋 반응 결과는 환원제로 순 알루미늄 분말을 사용한 경우와 같이 고순도 망간 합금철을 얻을 수 있었다. Al-15%Mn 합금분말를 이용한 $Mn_3O_4$ 분진의 망간 회수율은 알루미늄 분말을 이용한 경우의 약 65% 보다 높은 약 70%의 높은 수준을 보였으며, 이는 비산이 적은 것에 기인한다.

• 한국기계가공학회지
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• 제12권2호
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• pp.49-54
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• 2013

Recently welding of aluminum material is actively carried out to make lightweight in the fields of LNG vessels, aircraft, chemical plants, etc. To obtain high strength, hardness and elongation, elements such as manganese, zinc, silicon, etc should be added in aluminum alloy, which has been improved on the mechanical properties like precipitation hardening, age hardening, loosening, corrosion resistance acid resistance. Ar gas is used as a shielding gas of MIG welding for aluminum, also $N_2$, $O_2$, $CO_2$, $H_2$ etc can be added depending on the composition of the alloy. In this study, Ar + $O_2$, Ar, and He were used for welding, hardness, penetration status and changes in composition of penetrated parts were compared and analyzed. This made it possible to know the status and changes of the process in the penetrated parts depending on used gas throughout this study.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 춘계학술발표 개요집
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• pp.65-67
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• 1995

The solidification crack susceptifility of aluminum alloy weld metal have been evaluated by means of the slef restraint and external restraint cracking test. It has been observed expermently as follows : (1) The manganese is beneficial to decrease the solidification cracking susceptibility. (2) Weld metal containing zirconium is less sensitive to the solidification cracking than the weld metal containing chromium does. (3) The self restraint test method shows the same tendency in results as the external restraint test does.

• 한국주조공학회지
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• 제30권4호
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• pp.151-156
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• 2010

The high-strength low-alloy (HSLA) steels have low carbon contents (0.05~0.25% C) in order to produce adequate formability and weldability, and they have manganese contents up to 1.7%. Small quantities of silicon, chromium, nickel, copper, aluminum, molybdenum are used in various combinations. The results contained in this paper can provide the valuable information on the development of $-40^{\circ}C$ low temperature HSLA. Furthermore, the present experimental data will provide important database for casting steel materials of the offshore structure.

• Applied Microscopy
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• 제48권4호
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• pp.117-121
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• 2018

The multiple length scale analysis of previously designed Fe-Mn-Al-C based low-density model alloys reveals the difference in ordered ${\kappa}-carbide$, $(Fe,Mn)_3AlC_x$, between Fe-25Mn-16Al-5.2C (at%) alloy and Fe-3Mn-10Al-1.2C (at%) alloy. For the former alloy composition consisting of fully austenite grains, ${\kappa}-carbide$ showed majorly cuboidal and minorly pancake morphology and its chemical composition was not changed through aging for 24 h and 168 h at $600^{\circ}C$. Meanwhile, for the isothermally annealed ferritic alloy system for 1 hr at 500 and $600^{\circ}C$, the dramatic change in the chemical composition of needle-shape ${\kappa}-carbide$, $(Fe,Mn)_3(Fe,Al)C_x$, was found. Here we address that the compositional fluctuations in the vicinity of the carbides are significantly controlled by abutting phase, either austenite or ferrite. Namely, the cooperative ordering of carbon and Al is an important factor contributing to carbide formation in the high-Mn and high-Al alloyed austenitic steel, while the carbon and Mn for the low-Mn and high Al alloyed ferritic steel.

• 대한금속재료학회지
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• 제46권1호
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• pp.13-19
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• 2008

To develop a recycling process of magnesium alloy scrap, a fundamental study on the distillation of magnesium alloy melt was carried out. Melt temperature, vacuum degree and reaction time were considered as experimental variables. The amount of vaporized magnesium melt per unit surface area of melt increases with the increase of melt temperature, reaction time and vacuum degree. The vapor condensed at the tip of water cooling Cu-condenser as a form of pine cone. Magnesium and zinc were vaporized easily from the melt. However, It's difficult to separate magnesium and zinc by vacuum distillation because vapor pressure of zinc is similar to one of magnesium. The contents of aluminum, manganese and iron, etc. in residual melt increase due to the decrease of magnesium and zinc content after the distillation of magnesium alloy.

• 대한조선학회논문집
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• 제45권4호
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• pp.426-431
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• 2008

The high-strength low-alloy(HSLA) steels have low carbon contents($0.05{\sim}0.25%$ C) in order to produce adequate formability and weldability, and they have manganese contents up to 1.7%. Small quantities of silicon, chromium, nickel, copper, aluminum, molybdenum are used in various combinations. The results contained in this paper can provide the valuable information on the development of $-40^{\circ}C$ low temperature HSLA. Furthermore, the present experimental data will provide important database for casting steel materials of the offshore structure.

• 한국재료학회지
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• 제24권5호
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• pp.229-235
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• 2014

In this paper, the effects of precipitates and Mn-solute atoms on the recrystallization behavior of an Al-Mn alloy was studied using micro-Vickers hardness, electrical conductivity measurements and optical microscopy. Various thermo-mechanical processes were designed to investigate the different morphologies, and the solute concentration, of Mn in the matrix. The results indicate that the recrystallization temperature, $T_R$ and time, $t_R$, are influenced by the amount of M-solute atoms in the matrix, and that the recrystallization microstructure is influenced by the amount of precipitates. Recrystallization in the Slow-Cooling specimen was rapid due to its low concentration of Mn-solute atoms, and the crystal-grain size was the smallest due to finely distributed precipitates. However, in the case of the No-Holding specimen, elongated grains were observed at the low annealing temperature and the largest recrystallized grains were observed at the high annealing temperatures (compared with Slow-Cooling and Base specimens) due to the high Mn-solute atoms in the matrix.