• Journal of Welding and Joining
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• 제15권2호
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• pp.43-53
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• 1997

The complete joining method for dissimilar press punch materials and its real-time evaluation method is not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. This work was carried out to determine the proper friction welding conditions and to analyze mechanical properties of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch) using aluminum (A6061 for the interlayer material) as an insert material between the sintered carbide tool materials and the alloy steel. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.109-111
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• 2006

In this study, microstructure and mechanical properties for the friction stir welded 2519Al-T87 alloy of the thickness of 38.8mm were studied using DSC, OM, SEM and micro hardness tester. DSC analysis show that GP Zone, ${\theta}'$ and $\theta$ phases in upper part and ${\theta}'$ and $\theta$ phase in lower part of the FSW zone. Recrystallized large grains are observed in HAZ, and elongated small and large grain in the TMAZ. In SZ, very small grains forms by high plastic deformation and heat from friction by tool and specimen.

• 대한기계학회논문집
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• 제10권6호
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• pp.830-836
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• 1986

본 연구에서는 이러한 사실에 착안하여 프랑스의 Granjon에 의해 이미 개발된 용접부의 재용성이 탁월한 종래의 정적임플란트(implant)시험기를 정한.고안하여 아아 크용접부의 피로특성에 영향을 미칠 수 있는 제영향인자를 재현하여 간편하게 피로시 험을 할 수 있는 동적 임플란트시험기를 개발하였다. 이러한 시험기를 이용하여 저 온.고압력용강재에 대해서 다음과 같은 항목들을 구명할 목적으로 본 연구는 수행된 것이다.

• 동력기계공학회지
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• 제4권4호
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• pp.54-58
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• 2000

The complete joining method for dissimilar hot die punch materials and its real-time evaluation method are not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. So, this work was carried out to determine the optimal friction welding conditions and to analyze mechanical properties of friction welded joints of hot die punch materials (STD61 for the blade part of hot die punch) to alloy steel (SCM440 for the shank part of hot die punch) such as plunger. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• 대한기계학회논문집A
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• 제31권4호
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• pp.532-539
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• 2007

The 7075-T651 Al alloy was welded by friction stir welding. Microstructure, macro behaviors and fracture type in the nugget, thermo-mechanically affected zone(TMAZ) and heat affected zone(HAZ) of the welded part were compared to base metal. The microsturctures of nugget zone were compared with tool rotation speeds and various tool transition speed. When the rotation speeds were decreased and transition speeds were increased, the hardness of nugget zone were decreased. Also, the optimal microstructure was observed at the low rotation speed of 800rpm and the high transition speed of 124mm/min. The transgranular dimple and quasi-cleavage at fractured part of nugget zone were investigated.

• 대한조선학회지
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• 제9권2호
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• pp.43-48
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• 1972

Inertia friction welding, a relatively recent innovation in the art of joining materials, is a forge-welding process that releases kinetic energy stored in the flywheel as frictional heat when two parts are rubbed together under the right conditions. In a comparatively short time, the process has become a reliable method for joining ferrous, and dissimilar metals. The process is based on thrusting one part, attached to a flywheel and rotating at a relatively high speed, against a stationary part. The contacting surfaces, heated to plastic temperatures, are forged together to produce a reliable, high-strength weld. Welds are made with little or no workpiece preparation and without filler metal or fluxes. However, In order to obtain a good weld, the determination of the optimum weld parameters is an important problem. Especially, because the amount of the flywheel mass will be determined according to the initial rotating velocity values at the constant thrust load, the initial rotating velocity is an important factor to affect a weld character of the inertia-welded IN713C-SAE8630, which is used for the wheel-shafts of turbine rotors or turbochargers, exhausting valves, etc. In this paper, the effects of initial rotational velocity on a weld character of inertia-welded IN713C-SAE8630 was studied through considerations of weld parameters determination, micro-structural observations and tensile tests. The results are as the following: 1) As initial rotating velocity was reduced to 267 FPM, cracks and carbide stringers were completely eliminated in the micro-structure of welded zone. 2) As initial rotating velocity was reduced and flywheel mass was increased correspondingly, the maximum welding temperatures were decreased and the plastic working in the weld zone was increased. 3) As initial rotating velocity was progressively decreased and carbides were decreased, the tensile strengths were increased. 4) And also the fracture location moved out of the weld zone and the tensile tests produced, the failures only in the cast superalloy IN713C which do not extend into the weld area. 5) The proper initial rotating velocity could be determined as about 250 thru 350 FPM for the better weld character.

• 동력기계공학회지
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• 제21권3호
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• pp.102-107
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• 2017

A tungsten inert gas (TIG) welding method was used for the bonding of stainless steel. TIG welding using inert gas (He or Ar gas) is a method to prevent oxidation and nitriding of materials and to combine non-ferrous metals. This method has the advantage of obtaining a smooth weld surface. In this study, the welding characteristics of 304 stainless steel welded by TIG welding method were analyzed by using nondestructive technique. Ultrasonic and Acoustic Emission (AE) was applied to evaluate the micro-damage of TIG welded 304 stainless steel. The velocity and damping coefficient of ultrasonic wave showed a slight difference in HAZ, which is the welding part of stainless steel. The AE parameters of average frequency, rise time and event were analyzed for the dynamic behavior of stainless steel during loading. Optimal AE parameters for evaluating the degree of damage to the specimen have been derived. Fractograph and metal structures of 304 stainless steel using SEM and optical microscope were discussed.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.185-188
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• 2006

The sea water pipe of engine room in all kinds of ships is being surrounded with severe corrosive environment. Therefore it's leakage part due to corrosion is inevitably prevented by various welding method. In this case corrosion property of welded zone may be considerably different by each welding materials. In this study corrosion resistance of the welded zone of sea water pipe with some welding materials such as shielded metal arc welding materials, inert gas arc welding materials was investigated with electrochemical method.

• 대한기계학회논문집A
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• 제32권11호
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• pp.1028-1034
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• 2008

The exhaust systems are usually subjected to vibration or shock at high temperatures. The high temperature fatigue tests of the exhaust systems are rarely performed in domestic industries due to limited number of test facility and high test costs. In this paper, the high temperature fatigue test of some part of the exhaust system, not the whole system, is carried out. The resonator located at the central range is heated in the cylindrical electric furnace and the alternating load is applied on the end of the pipe welded to the resonator. The high temperature fatigue strength of the welded joint is obtained. The location of the fatigue crack is different to that in room temperature.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1992년도 특별강연 및 춘계학술발표 개요집
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• pp.81-84
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• 1992