• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1661-1667
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• 2008

Recently, a rolling stock has been requiring more efficient manufacturing method than welding for the improved quality and the enhanced fabrication of car body structure. As an alternative, modularization of car body structure is being studied. Accordingly, rolling stock manufacturers need to make it possible to develop a variety of rolling stock vehicles made from modularized sub-blocks in order to meet various customer's demands. The bolt-assembled car body structure for modularization is known to have many advantages over the existing weld-assembled method and is free from the possible welding defects, such as welds between dissimilar metals, crack, deformation and loss of strength. Consequently, we can have the improved overall quality, the reduced man powers for assembly and the satisfied strength of car body structure. The review is about the bolt-assembled car body structure for modularization to assure global competitiveness and an enhanced technique in terms of assembly methodology of car body structure.

• 대한기계학회논문집
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• 제11권6호
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• pp.953-962
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• 1987

본 연구에서는 국산 구조용강의 SM 45C 와 SUS 304 재를 최고 강도치가 나타 나는 압접조건하에서 압접하여 우재료의 용착금속부, 열영향부, 각 모재부 소정의 장 소에 미소원공을 가공한 시험편을 토대로 피로크랙의 발생 및 전파거동을 응력 레벨의 고저를 고려하여 고찰하였다.

• Journal of Welding and Joining
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• 제34권1호
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• pp.59-67
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• 2016

The automotive manufactures increase their use of lightweight materials to improve fuel economy and energy usage has a significant influence on the choice of developing materials. To meet this requirements manufacturers are replacing individual body parts with lightweight metals, for these the process treating and painting surfaces is changing. The pre-coated steels are newly developed to avoid the conventional complex and non-environmental painting process in the body-in-white car manufacturing. The development of new joining techniques is critically needed for pre-coated steel sheets, which are electrically non-conductive materials. In the present study, dissimilar combination of pre-coated steel and galvanized steel sheets were joined by the self-piercing rivet, adhesive bonding and hybrid joining techniques. The tensile shear test and free falling high speed crash test were conducted to evaluate the mechanical properties of the joints. The highest tensile peak load with large deformation was observed for the hybrid joining process which has attained 48% higher than the self-piercing rivet. Moreover, the hybrid and adhesive joints were observed better strain energy compared to self-piercing rivet. The fractography analyses were revealed that the mixed mode of cohesive and interfacial fracture for both the hybrid and adhesive bonding joints.

• 대한기계학회논문집A
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• 제34권3호
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• pp.333-340
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• 2010

본 논문은 Alloy 82/182를 용가재로 사용한 SA508 Gr.3 노즐과 F316L 스테인리스강 안전단 사이의 이종금속 용접부에서 상온의 인장물성치와 파괴물성치를 평가하였다. 이를 위해서 두 모재와 열영향부, 버터링부, 그리고 용접부 내의 각 위치에서 채취된 시편을 이용하여 인장시험과 J-R 시험을 수행하였다. 시험 결과 Alloy 82/182 용접 루터부가 상부에 비해 높 은 강도를 보였다. 용접 루터부에서는 항복강도와 인장강도가 위치에 따라 크게 변화하였다. 버터링 부분이 가장 낮은 강도를 보였으며, F316L 스테이리스강 인접부로 갈수록 강도가 증가하였다. 반면, 용접 상부에서는 위치에 따른 강도의 변화가 크지 않았다. Alloy 82/182 용접부는 모재와 열영향부에 비해 낮은 파괴인성을 보였다. Alloy 82/182 용접부 내에서는 용접부 중심이 용접 경계부와 버터링부에 비해 약간 낮은 파괴인성을 보였으며, 용접 루터부가 용접 상부에 비해 높은 파괴인성을 보였다.

• 대한기계학회논문집
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• 제11권5호
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• pp.762-771
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• 1987

본 연구에서는 국산 구조용 강인 SM45C와 SUS304재를 마찰가열압력과 업셋압 력을 서로 변화시키고 업셋시간을 2초로 고정하여 압접시간 10초를 기준으로 하여 변 화시키면서 마찰압접한 후 압접시간 변화에 따른 인장강도의 변화와 업셋량 변화에 따 른 인장강도 및 굽힘강도를 고찰하였다.또 최고 강도치를 나타내는 압접조건을 구 한 후 미소 경도치 및 이종재의 압접부에서 미소하게 변화하는 조직변화도 함께 고찰 하였다.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1163-1169
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• 2012

초탄성 재료인 고무는 타이어의 주 원료인데, 주행 중 다양한 형태의 하중을 받는다. 그와 같은 하중에 의하여 타이어에 변형률에너지가 축적되어 파손에 이르게 된다. 일반적으로 초탄성재료인 고무는 금속과 다른 응력연화 특성을 갖고 있기 때문에 금속의 시험법을 적용할 수 없다. 따라서 본 연구에서는 조성비가 다른 2 종의 타이어용 고무에 대한 피로특성을 평가하기 위하여, ASTM D4482 규격에서 요구하는 변형률 범위를 확장하여 인장 및 피로시험을 진행하였으며, 실험 결과를 이용하여 피로수명식을 제안하였다.

• 대한기계학회논문집A
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• 제24권2호
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• pp.438-448
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• 2000

Mechanical press joining technique has been used in sheet metal joining processes because of its simple process and possibility of joining dissimiliar metals, such as steel and aluminum. The static and cyclic behavior of single overlap AI-alloy and steel(SPCC) joints has been investigate. Relationships were developed to estimate the strength of the joint taking into consideration base metal strength properties and the geometry of the joint. Fatigue test results have shown that fatigue resistance of the SPCC mechanical press joints is almost equal to that of the spot weld at the life of $10^6$ cycles. Also, the dissimilar material jointed specimen with upper SPCC plate and button diameter corresponding to the nugget diameter of the spot welded specimen has almost same strength as the same material jointed specimen and as the spot welded specimen.

• 열처리공학회지
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• 제29권2호
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• pp.66-74
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• 2016

In this study, characteristics of TiAl alloy and SCM440 (Cr-Mo steel) have been investigated with the various joining condition by servo motor type friction welder. The experimental factors of friction welder used in this study are spindle revolution, friction speed, and distance, upset speed and distance, respectively. Servo motor type friction welder could be controlled by the level of oil pressure, and it could be performed by position control dependence of electrical energy. Mechanical properties and morphology of welded interface were characterized by various joining condition. This aroused due to the bond strength dependence on friction heat and size of the heat affected zone. Therefore, it is necessary to have enough friction heat and decreased heat affected zone for good friction welding between dissimilar metals. An optimum bond was obtained between TiAl alloy and SCM440 by controlling friction speed and distance. At the spindle revolution 4,000 rpm, friction speed 120 mm/min, friction distance 15 mm, the bond strength was found to be 312 MPa.

• 한국공작기계학회논문집
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• 제11권3호
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• pp.65-71
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• 2002

Friction welding has may merits such as energy efficiency, simple processing, etc. but it is difficult to obtain good welding at the welded interfaces and heat affected zone. It is discovered that stress singularity exists at the interferes and heat affected zone. The computer program based on boundary element method is utilized in this study. A mathematical model is implemented based on results from several experiments performed at and around the welded interfaces and heat affected zone of disimilar metals under static and dynamic loadings. This stay is to investigate the characteristics of the deformation and fracture behavior around interfaces for friction welded materials under static tensile load. Also, the stress distribution at the tip of crack is analyzed by using BU based on Kelvin's solution of 2-dimensional binding zone. The results of BEM are identical with those in case of considering interfaces of both heat affected zone. Also, stress singularity at the tip of interfaces appears when the elastic modulus ratio is 1.07.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.205.2-205.2
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• 2014

The effects of ion beam mixing of a SiC film coated on super alloys (hastelloy X substrates) were studied, aiming at developing highly sustainable materials at above $900^{\circ}C$ in decomposed sulfuric acid gas (SO2/SO3/H2O) channels of a process heat exchanger. The bonding between two dissimilar materials is often problematic, particularly in coating metals with a ceramics protective layer. A strong bonding between SiC and hastelloy X was achieved by mixing the atoms at the interface by an ion-beam: The film was not peeled-off at ${\geq}900^{\circ}C$, confirming excellent adhesion, although the thermal expansion coefficient of hastelloy X is about three times higher than that of SiC. Instead, the SiC film was cracked along the grain boundary of the substrate at above $700^{\circ}C$. At ${\geq}900^{\circ}C$, the film was crystallized forming islands on the substrate so that a considerable part of the substrate surface could be exposed to the corrosive environment. To cover the exposed areas and cracks multiple coating/IBM processes have been developed. An immersion corrosion test in 80% sulfuric acid at $300^{\circ}C$ for 100 h showed that the weight retain rate was gradually increased when increasing the processing time.