Friction stir spot welding (FSSW) is a solid-state joining process and a rapidly growing dissimilar material welding technology for joining metallic alloys in the automotive industry. Welding tool shape and process conditions must be appropriately controlled to obtain high bonding characteristics. In this study, FSSW is performed on dissimilar materials AA5052-H32 aluminum alloy sheet and SPRC440 steel sheet, and the influence of the shape of joining tool and tool insertion depth during joining is investigated. A new intermetallic compound is produced at the aluminum and steel sheets joint. When the insertion depth of the tool is insufficient, the intermetallic compound between the two sheets did not form uniformly. As the insertion depth increased, the intermetallic compound layer become uniform and continuous. The joint specimen shows higher values of tensile shear load as the diameter and insertion depth of the tool increase. This shows that the uniform formation of the intermetallic compound strengthens the bonding force between the joining specimens and increases the tensile shear load.

In this study, we investigated the change in fracture properties after friction stir welding on Al606. In the L-T direction test, the fracture toughness of the unwelded base material was 275 MPa, and the specimen subjected to friction stir welding (FSW) was 227 MPa, showing that the fracture toughness decreased significantly with friction stir welding. In the T-L direction test, the difference between the base material and the weld material was not large, but the fracture toughness was shown to decrease during welding. In the comparison of the L-T direction and the T-L direction, it was found that both the base material and the weld material showed high fracture toughness in the L-T direction.In this study, the following conclusions were obtained after friction stir welding of Al 6061-T6.

Power converter devices require a high level of quality because they have a high direct connection with vehicle operation. Therefore, structural bonding was carried out by friction stir welding with excellent mechanical properties. Friction stir welding can cause structural deflection depending on the load of the welding tool, so it is important to control this for high quality flatness. In this study, pre-welding was performed before welding to minimize deflection generated during welding. And deflection reduction data according to the location of pre-welding were analyzed through dynamic analysis. As a result, based on computerized data rather than experimental data an optimized position of pre-welding was secured to minimize the deflection that occurs during friction stir welding. Through this, a process guide that enables high quality structural bonding was presented.

In this study, the following conclusions were obtained after friction stir welding of Al 6061-T651. 1) The organization of the welding unit is largely divided into four parts, the Stir zone, themal-mechanical affected zone, heat affected zone, it was confirmed that it is clearly separated into the material portion. 2) As a result of observing the hardness test results of the welding unit, the minimum hardness value was about 45Hv, which was significantly lower than the hardness of the base material about 72Hv. 3) The tensile strength of the welding part was about 2/3 compared to the tensile strength of the base material.

In this study, experiments and simulations were performed for fillet joint friction stir welding according to tool shape and welding conditions. Conventional butt friction stir welding has good weldability because heat is generated by friction with the bottom of the tool shoulder. However, in the case of fillet friction stir welding, the frictional heat is not sufficiently generated at the bottom of the tool shoulder due to the shape of the tool and the shape of the joint. Therefore, it is important to sufficiently generate frictional heat by slowing the welding speed as compared to butt welding. In this study, experiments and simulations were carried out on an aluminum battery housing made by friction stir welding an extruded material with a fillet joint. The temperature of the structure was measured using a thermocouple during welding, and the heat source was calculated through correlation analysis. Thermal elasto-plastic analysis of the structure was carried out using the calculated heat source and geometric boundary conditions. It is confirmed that the experimental results and the simulation results are well matched. Based on the results of the study, the deformation of the structure can be calculated through simulation even if the tool shape and welding process conditions change.

Recently, the use of non-ferrous metals has been increasing to lighten the weight of automobiles and parts. In particular, demand for non-ferrous alloy materials such as aluminum alloys and magnesium alloys is increasing. The purpose of this study is to calculate the optimization process of friction stir welding by using different materials of AA5052 and AA6061. By analyzing the reaction value of tensile strength and elongation by full factorial design and Custom Design Methodology. In other words, we analyzed the optimization process according to rotation speed, feed rate, tool angle and tool shape. In conclusion, the optimal process for tensile strength was achieved by using a tool with a rotation speed of 900 RPM, feed rate of 270, tool angle of 2.5° and a triangle tool. and The rotation speed was 1003 RPM, the feed rate was 314.5, tool angle of 1° and a triangle tool, it was able to get the maximum value of elongation when using a tool of the form.

In this study, the deformation of friction stir welding on the aluminum battery housing material(AL6063-T5) applied to the electric vehicle was effectively predicted through experiments and numerical simulations. The temperature data were measured during the friction stir welding experiment, and the numerical simulation was carried out using the experimental temperature data. In the heat transfer analysis, the temperature distribution of the structure over time was calculated using the Reynolds equation. The final friction stir welding deformation was calculated by performing the structural analysis using the calculated temperature distribution data over time. The thermal elasto-plastic analysis was performed according to the friction stir welding process conditions and the welding sequences. Finally, the optimum welding condition was derived that the welding speed is 1000 mm/min and the rotation speed of the tool is 2000 RPM.

Since the directly bonded interface between TiAl alloy and SCM440 includes lots of cracks and generated intermetallic compounds(IMCs) such as TiC, FeTi, and Fe2Ti, the interfacial strength can be significantly reduced. Therefore, in this study, Cu is selected as an insert metal to improve the lower tensile strength of the joint between TiAl alloy and SCM440 during friction welding. As a result, newly formed IMCs, such as Cu2TiAl, CuTiAl, and TiCu2, are found at the interface between TiAl alloy and Cu layer and the thickness of IMCs layers is found to vary with friction time. In addition, to determine the relationship between the thickness of the IMCs and the strength of the welded interfaces, a tensile test was performed using sub-size specimens obtained from the center to the peripheral region of the friction-welded interface. The results are discussed in terms of changes in the IMCs and the underlying deformation mechanism. Finally, it is found that the friction welding process needs to be idealized because IMCs generated between TiAl alloy and Cu act to not only increase the bonding strength but also form an easy path of fracture propagation.

In this study, SM45C-STKM13B hollow shaft of different thickness was joined by friction welding. After friction welding, we treated to specimen of annealing(post-weld heat treatment). The specimens were tested as-welded and post-weld heat treatment(PWHT). The mechanical properties including tensile test and vickers micro-hardness were examined. And then, the mechanical properties were compared for as-welded and PWHT in SM45C to STKM13B. Microstructure of joining part were examined in the weld interface and weld region and heat affected zone and base metal of weld parts.

Friction welding in dissimilar materials is widely applied in various engineering fields such as automobiles, rolling stocks, machine tools. Since interface edges of Friction-welded materials have stress singularity by differences of mechanical properties and temperature changes, it is necessary to assess stress singularity with the variation of flash shape and length. In this paper, the influences which the flashes created by friction welding concern to the stress singularity at interface edges are investigated. Through stress analysis by the BEM and static experiments, the influences were studied quantitatively, the stress singularity greatly depends on the shape of the flash and its size.

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heat-treated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed,and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out ata tool rotation speed of 200 rpm and tool down force of 19.6-39.2kN; post-heat-treatment with two steps was carried out at720oC for 8h and 620oC for 6h in vacuum. To prevent the surface oxidation of the specimen, the method of using argongas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective todevelop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties ascompared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated theformation of precipitates, such as gamma prime (γ') and MC carbides, which led to the significant improvement of mechanicalproperties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased morethan 110%, 124% and 85%, respectively, relative to the overlap welded material. This study systematically examined therelationship between precipitates and mechanical properties.

With increasing use of SUH35/SUH3 dissimilar materials for automotive engine valves, it is required that stress singularities under residual stress on an interface for friction welded dissimilar materials analyzed to establish strength evaluation. The stress singularity index() and stress singularity factor( ) were calculated by using the results of stress analysis considering residual stress and loads. The stress singularities on variations for temperatures and loads acting from outside were analyzed and discussed. This paper suggested that the strength evaluation by using the stress singularity factors as fracture parameters, considering the stress singularity on an interface edge of friction welded dissimilar materials will be useful.

선박 구조재료 FRP 재료의 대체 재료로 빠른 선속과 선적량 증가는 물론 재활용이 용이한 Al 선박으로 전환되고 있다. 본 논문에서는 인장실험을 통해 레저선박에 사용되는 5456-H116 합금에 대한 최적의 마찰교반용접 조건에서 프루브 직경의 효과를 기술하였다. 마찰교반용접에서 이송속도, 회전속도를 변수로 5 mm의 프루브 직경을 사용하여, 이송속도가 61 mm/min의 조건에서 가장 우수한 결과를 나타냈다. 프루브 직경 6 mm, 회전속도 170-210 rpm, 이송속도 15 mm/min 에서는 낮은 회전속도로 인하여 불충분한 용접열이 발생하여 거친 표면과 기공이 형성 되었다. 회전속도 500-800 rpm인 경우, 용접부에 칩이 관찰되었으며, 기공은 생기지 않았고, 용접표면은 우수하였으나 1100-2500 rpm에서는 지나친 용접열의 발생으로 많은 칩이 발생하였다. 열에 의한 영향은 용접 배면에서 관찰되었다. 이송속도가 15 mm/min에서 회전속도의 증가하게 되면 마찰이 증가함에 따라 용접열이 발생한다. 기계적 특성은 용접 입열량이 증가할수록 재질의 연화가 가속화되어 저하하였다.

The shock absorber base assembly is one of the parts in the shock absorber equipment that controls the vehicle movement. It absorbs the shock and vibration to guarantee riding stability and comfort. It demands strength, reliability and strict airtightness

Shock absorber base assembly is one of the parts in shock absorber equipment which control the vehicle movement and absorb the shock and vibration to realize the stability and the comfort for the riding. This part demand hardness, reliance and rigorous density of the welded section because it is a resist pressure container which needs durability by being filled with gas and oil. However, the present engineering needs much time, high cost and shows low production rate due to the eight processes which are spot welding, reinforcement welding(MAG), prior process of base cap and tube for the precision and pressing etc. In this study we will analyze the problem of the processes for the base assembly and suggest an engineering to improve the problem innovatively using frictional welding. As the result of experiment by frictional welding using frictional heat, its hardness for the joining section became high and its precision showed excellence. Therefore we can expect the curtailment for the welding processes, the reduction of cost and excellent joining function.

Friction welding of particulate reinforced aluminum composites was performed and the following conclusions were drawn from the study of interfacial bonding characteristics and the relationship between experimental parameters of friction welding and interfacial bond strength. Highest bonded joint efficiency (HBJE) approaching was obtained from the post-brake timing, indicating that the bonding strength of the joint is close to that of the base material. For the pre-brake timing, HBJE was . Most region of the bonded interface obtained from post-brake timing exhibited similar microstructure with the matrix or with very thin, fine-grained layer. This was attributed to the fact that the fine-grained layer forming at the bonding interface was drawn out circumferentially in this process. Joint efficiency of post-brake timing was always higher than that of pre-brake timing regardless of rotation speed employed. In order to guarantee the performance of friction welded joint similar to the efficiency of matrix, it is necessary to push out the fine-grained layer forming at the bonding interface circumferentially. As a result, microstructure of the bonded joint similar to that of the matrix with very thin, fine-grained layer can be obtained.

이종재 마찰용접재 강도특성과 초음파 반사계수와의 상관성에 관하여 실험적으로 연구한 결과의 요약은 다음과 같다. 1. 이종재 마찰용접 이음면에서의 초음파 반사계수를 펄스반사법에 의하여 측정산출할 수 있다. 2. 5MHz의 비교적 낮은 주파수의 탐촉자를 사용하므로써 시험편의 표면가공 오차를 무시할 수 있다. 3. 알루미늄과 스테인레스의 마찰용접에서는 용접조건으로 마찰가열시간이나 가열압력을 변수로 하였을 때보다 업셋가압력을 변수로 하였을 때 반사계수의 변화가 뚜렷하다. 4. 업셋가압력을 변수로 한 용접조건과 반사계수사이에는 선형적 상관관계가 있다. 5. 용접이음면에서의 이음인장강도와 반사계수와의 상관관계식을 정량적으로 도출할 수 있다. 6. 초음파 반사계수에 의해 이종재 마찰용접 품질의 비파괴적 평가가 가능하다