• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 1997년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
• /
• pp.5-5
• /
• 1997

Rapidly-solidified P/M aluminium alloys for automobile and home appliance industries were developed. Rapidly-solidification made it possible to refine microstructures and to expand the range of alloy composition. For example, Al-Si alloys containing transition metal have lower thermal expansion coefficient, more excellent wear resistance, higher strength, and better machinability than those of conventional aluminium alloys. Therefore, in Japan, the technologies on powder-extrusion and powder-forging of aluminium alloy powders are developed for fifteen years, and applied to several parts, such as cylinder liners of motor cycle engines, rotors and vanes of compressors for car air conditioner, oil pump rotor for racing car, and so on. In this presentation, applications for automobile are mentioned. In particular, cylinder liners made of particle-dispersed composites with fine alumina and graphite are in detail described.

• Corrosion Science and Technology
• /
• 제15권4호
• /
• pp.153-158
• /
• 2016

Light metal alloys of Mg, Ti, and Al undergo environmentally assisted cracking (EAC). Passive film breakdown and pitting are not only precursor events for stress corrosion, but can accelerate hydrogen evolution that is responsible for hydrogen embrittlement. This is clearly demonstrated in the case of Mg and Ti alloys. The so-called innocuous precipitates, which do not directly participate in either alloy strengthening or EAC can be effective precursors for initiating EAC. This aspect is highlighted using high strength aluminium alloys. Such behaviours lead to a paradigm shift in the design of alloys with resistance to EAC.

• Journal of Advanced Marine Engineering and Technology
• /
• 제31권5호
• /
• pp.567-574
• /
• 2007

Aluminum and aluminum alloys have high rate of lightness, recycling property and excellent specific strength. Fields using them have been widening because they ould satisfy both energy reduction and high efficiency in manufactures production. But they have many problems on welding due to high thermal conductivity and reflectivity, so the study to solve these problems ate proceeding actively around the world. This study was purposed to improve weldability and spread application range for aluminium alloys by using the unique property of aluminium which absorb high energy around $800{\mu}m$ wavelength and the higher temperature, the mote absorbtion of laser beam on preheating by multi-wavelength laser beam(pulsed Nd:YAG laser + diode laser with $808{\mu}m$ wavelength). The favorable mechanical properties were acquired by the test results of strength, hardness and leak of weld metal which had reduced its defect like crack and so on.

• 열처리공학회지
• /
• 제33권4호
• /
• pp.161-172
• /
• 2020

The tensile property of A5082 and A6060 aluminium wrought alloys was investigated, in terms of the strain rate sensitivity on alloy conditions by heat treatment and bake hardenability on pre-strain prior to strain ageing. The tensile test was carried out in a range of strain rate of 4.17 × 10^-5 s^-1 ~ 4.17 × 10^-5 s^-1 in room temperature and the nominal range of pre-strain was 3.0 ~ 10.5%. The tensile deformation of A5082 alloys is characterized as typical case of dynamic strain ageing with negative strain rate sensitivity for all conditions, and the tensile strength indicates a similar level regardless of alloy conditions, except only in full annealed condition. The stress-relief annealing on A6060 alloys can induce practical decrease in strength level of over approximately 100 MPa without any ductility loss, compared to as-rolled condition, while a full annealed and aged condition leads remarkable strengthening effect with the decrease of tensile elongation. Additionally, the bake hardenability of A5082 alloy by strain ageing indicates a negative dependence upon the increase of pre-strain, while A6060 alloy exhibits a positive sign even in low level relatively compared with conventional SPCC.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1993년도 춘계학술발표회
• /
• pp.29-30
• /
• 1993

• Corrosion Science and Technology
• /
• 제2권1호
• /
• pp.30-35
• /
• 2003

In this study, sand cast AZ91E and zirconium grain refined MEZ are representative of two typical groups of magnesium alloys: those containing aluminium and those containing no aluminium but with zirconium as a grain refiner. The corrosion performance of these two alloys was evaluated and compared in 5%wt NaCI solution through measurements of weight loss and polarisation curves and examination of microstructure. Corrosion damage of AZ91E was deeper and more localised than that of MEZ, while MEZ had a lower rate of cathodic hydrogen evolution and a higher rate of anodic dissolution than AZ91E. These differences in behaviour can be related to the differences in microstructure and chemical composition between the two alloys.

• 한국주조공학회지
• /
• 제32권2호
• /
• pp.86-90
• /
• 2012

Aluminium-silicon based casting alloys have received an attention for high electrical and thermal conductivity applications, however relatively low conductivity of Al-Si alloys often limits the application. Efforts have been made to develop new high conductivity aluminium casting alloys containing no or less silicon. In this study Al-Zn-Fe based alloys were selected as the new alloys, and the effect of Mg additions on their properties and casting characteristics were investigated. As the magnesium content was increased, the tensile strength of Al-2Zn-0.2Fe based alloy was remarkably increased, while the electrical conductivity was deteriorated. It was observed that the fluidity of the alloys was generally inversely proportional to the Mg content but the hot cracking resistance was rather proportional to it. Cooling curve analyses were carried out to measure the actual solidification range and dendrite coherency temperature.

• 한국기계가공학회지
• /
• 제10권6호
• /
• pp.56-62
• /
• 2011

In this study, a method for the press forming of rectangular aluminium tube has been proposed. Rectangular aluminium tube has high stiff as the cold steel which can be lighter over 30% weight. It is increased every year by being recycled over 80%. Press die consists of punch, wing-die and holder for aluminium tube bending. When punch is applied with aluminium tube, holder is operated as same punch and wing-die is rotated through hinge. Stress-strain relations and springback are considered by bending angle of aluminium tube. In this study, the behaviors on tubes of square aluminium and rectangular aluminium with different thickness and area are established by the analysis of $DEFORM^{TM}$-3D program. Reducing fuel consumption is expected by using the aluminium tube deformation and it becomes the lightweight through recycling.

• 한국주조공학회지
• /
• 제13권3호
• /
• pp.259-267
• /
• 1993

The effects of casting processes-direct and indirect squeeze casting, permanent mold casting and die casting on the microstructure and mechanical properties were studied for the hypereutectic B390 aluminium alloy. The effects of T5 and T6 heat treatment were also examined. The direct and indirect squeeze casting showed no casting defects such as porosity and shrinkage were observed in permanent mold castings and die castings. The primary silicon phase was refined and homogeneously distributed in the order of indirect squeeze casting, diecasting, direct squeeze casting and permanent mold casting. Depletion of primary silicon phase in die casting surface was disappeared in indirect squeeze casting. Tensile strength of cast and heat treated specimens were increased in the order of direct squeeze casting, permanent mold casting, indirect squeeze casting and die casting. Hardness of indirect squeeze castings was larger than that of other castings. As indirect squeeze casting of B390 aluminium alloy, the time of T6 heat treatment to achieve high strength can be reduced.

• 한국주조공학회지
• /
• 제25권4호
• /
• pp.161-167
• /
• 2005

The experiment of hot dip interaction tests was carried out in order to study the formation behavior of interfacial reaction layer between as-received STD61 hot work tool steel and a commercial pure aluminum melt, Al-xwt.%Fe(x=0.2, 0.5, 0.8 and 1.1) alloys melt and Al-xwt.%Si(x=1.0, 4.0, 7.0 and 10.0) alloys melt, respectively. The results show that the reaction layer, over 300 ${\mu}m$ in thickness, is easily formed by the dissolution of silicon from as-received tool steel. When the iron content in the aluminum alloy is higher than 1.1 wt.%, the thickness of reaction layer decreases below 180 ${\mu}m$ by preventing iron dissolution from the tool steel. The silicon dissolved from tool steel acts as a strong promoter on the formation of reaction layer, but the alloyed silicon in molten aluminum alloys acts as an inhibitor on the formation of reaction layer.