Effect of friction stir welding parameters on fatigue resistance, weld quality and mechanical properties of Al 6061-T651 / Mohamed Ackiel Mohamed and Yupiter HP Manurung

The present work examined the fatigue life cycle, tensile behavior, nugget zone hardness and weld quality of friction stir welded Al 6061-T651 with varying welding parameters. The joining process was conducted with varied process parameters namely the rotational speed and traverse speed on butt joints with plate thickness of 6mm. The experimental method was based on a full factorial design with varied parameters between 350-1400 rpm and 0.2-4.6 mm/s for rotational speed and traverse speed respectively utilizing four levels for each parameter. The fatigue life cycle for each variation was determined. The zone formation and internal weld defects were analyzed using digital x-ray and macroscopically with a designated weld class for each parameter variation. Furthermore, the causes of internal weld defects and the effect of zone formation on tensile strength properties and hardness profile were discussed and concluded. The best mechanical properties are obtained at higher traverse speeds with moderate rotational speed probably owing to the incidence of homogeneous grains and higher heat input. Two parameter variations displayed a combination of good weld class quality and mechanical properties namely rotation speed 950rpm with 4.6 mm/s traverse speed as well as 650 rpm rotation speed with 2.4 mm/s traverse speed. An increase in the nugget hardness shows an increment in the fatigue life

Analysis of Weld Induced Distortion of Butt Joint using Simulation and Experimental Study / Mohd Shahar Sulaiman ...[et al.]

This paper focuses on investigation of welding distortion that occurred due to GMAW process which can adversely affect the dimensional accuracy and aesthetical value of the welded structure. Distortion can lead to production delay and costly remedial work. Based on this fact, it is necessary to predict the welding distortion in advance in order to produce high quality welded parts and thus to reduce production cost. In this study, the welding distortion induced in butt joint with thickness of 4 mm was simulated using Finite Element Method (FEM) software Simufact.Welding Version 5. The welding deformation was computed based on non-linear thermo-elastic-plastic numerical analysis. Low carbon steel material was employed for the simulation and experimental study. A series of experiments using fully automated welding process were carried out for verification purpose in order to measure the distortion. By comparing the results between simulation and experiment, it was found out that a good agreement was achieved and fast solution analysis time was provided in predicting weld induced distortion

A Quality Improvement Approach for Resistance Spot Welding using Multi-objective Taguchi Method and Response Surface Methodology

This research deals with an approach for optimizing the weld zone developed by the resistance spot welding (RSW). This approach considers simultaneously the multiple quality characteristic (weld nugget and heat affected zone) using Multi-objective Taguchi Method (MTM). The experimental study was conducted under varying welding currents, weld and hold times for joining two sheets of 1.0 mm low carbon steel. The setting of welding parameters was determined using Taguchi experimental design method and L9 orthogonal array was chosen. The optimum welding parameter for multi-objectives was obtained using multi signal to noise ratio (MSNR) and the significant level of the welding parameters was further analyzed using analysis of variance (ANOVA). Furthermore, the first order model for predicting the weld zone development was developed by using Response Surface Methodology (RSM). Confirmation experiment was conducted at an optimal condition for observing accuracy of the developed response surface model. Based on the confirmation test results, it is found out that the developed model can be effectively used to predict the size of weld zone which can improve the welding quality and performance in RSW

Fatigue Life Assessment of 9mm Thickness Low Carbon Steel with Multi-Objective Optimized Welding Process / Azrriq Zainul Abidin...[et al.]

Gas Metal Arc Welding (GMAW) is one of the popular methods in joining metal in manufacturing industries. However the transient thermal stresses and non-uniform distribution of elastic strains is produced by the weld causes residual stresses and distortion, thus affecting the fatigue performance of the welded structure. The used of Robotic Welding (RW) allows this welding process parameters to be controlled significantly to improve the welding quality. First, Multi-Objective Taguchi Method (MTM) were used to analyse optimum parameters value which started application of common Taguchi methods (L8) Orthogonal Array (OA) and Total Normalized Quality Loss (TNQL) followed by ANOVA under simultaneous consideration response factors. The value was furthermore analysed by applying Multi-Signal to Noise Ratio (MSNR). The two (2) optimize welding parameter ranges are selected to be used for fatigue life assessment on the 9 mm plate which is labelled as set A and B. Tensile test was carried out on the specimen prior to fatigue testing to know the value of yield strength and UTS of the specimens. The fatigue test was carried out on three (3) type of specimen with one sample without any welding as controlled specimen. It can be concluded that welding parameters of set A is more superior for fatigue performance of this 9 mm low carbon steel plate

Fatigue Life Enhancement of Transverse and Longitudinal T-Joint on Offshore Steel Structure HSLAS460G2+M using Semi-automated GMAW and HFMI/PIT

This research deals with a method and procedure for enhancing the structural life of the commonly used steel structure in oil and gas industries HSLA S460G2+M with a thickness of 10 mm. The type of joint and welding process is T-joint with transverse and longitudinal attachment welded using semi-automated GMAW. Filler wire ER80S-Ni1 and mixed shielding gas (80% Ar / 20% CO2) is used as material consumables. At first, the best suitable welding parameters are comprehensively investigated, prepared, tested and qualified according to welding procedure specification (WPS) qualification requirements. Further, the weld toe is treated by using HFMI/PIT with a frequency of 90Hz, 2 mm pin radius and air pressure of 6 bars. In accordance with the recommendation of the International Welding Institute (IIW), fatigue test is conducted using constant amplitude loading with the stress ratio of 0.1 and loading stresses from 55% to 75% of the yield strength of the material. Finally, the results of the fatigue experimental are compared with the fatigue recommendation of as-welded and HFMI/PIT of IIW as well as the untreated raw material. As a conclusion, it is observed that the fatigue life is increased up to 300% compared to IIW and 70% to as-welded. It is also obvious that treated transverse T-joint shows significant improvement than the longitudinal attachment

Development of Bead Modelling for Distortion Analysis Induced by Wire Arc Additive Manufacturing using FEM and Experiment

In this research, Wire Arc Additive Manufacturing is modelled and simulated to determine the most suitable bead modelling strategy. This analysis is aimed to predict distortion by means of thermomechanical Finite Element Method (FEM). The product model with wire as feedstock on plate as substrate and process simulation are designed in form of multi-layered beads and single string using MSC Marc/Mentat. This research begins with finding suitable WAAM parameters which takes into account the bead quality. This is done by using robotic welding system with 01.2mm filler wire (AWS A5.28 : ER80SNi1), shielding gas (80% Ar/ 20% CO2) and 6mm-thick low carbon steel as base plate. Further, modelling as well as simulation are to be conducted with regards to bead spreading of each layers. Two different geometrical modelling regarding the weld bead are modelled which are arc and rectangular shape. Equivalent material properties from database and previous researches are implemented into simulation to ensure a realistic resemblance. It is shown that bead modelling with rectangular shape exhibits faster computational time with less error percentage on distortion result compared to arc shape. Moreover, by using the rectangular shape, the element and meshing are much easier to be designed rather than arc shape bead

Comparative Distortion Analysis of Welded T-Joint between 2D-Shell and 3D-Solid Element using FEA with Experimental Verification / Keval. P Prajadhiana...[et al.]

In this paper, three different finite element simulations of welded T-Joint are to be computed using 2D-shell and 3D-solid element types. The assigned element types are built and modelled on T-joint plate with thickness of 4 mm. The thermo-mechanical FEM simulation using MSC Marc/Mentat is implemented throughout the analysis. The angular distortion induced by welding process on the web is to be analysed under similar heat input and clamping condition on the stiffener. The selected heat source model is Goldak’s double ellipsoid which is normally used for arc welding processes.In order to verify the simulation process, selected one-pass and double-sided GMAW process with fully automated experimental procedure was conducted using the exactly similar parameters assigned in FEM simulation. A measurement point analysis is furthercarried out to assess the displacement value of the actual T-Joint welding process by using Coordinate Measuring Machine (CMM) and to compare with the result of FEM simulation.It is found out that, for this kind of joint design and geometry, conducted FEM procedure shows good agreement on distortion tendency of the web within the range of percentage error up to 20%. However, the element types shell and solid without table do not indicate significant difference in simulation result compared to solid element with table

Optimization of HFMI/PIT Parameters with Simultaneous Multiple Response Consideration using Multi-Objective Taguchi Method for Fatigue Life Enhancement of Friction Stir Welding

The friction stir welding process is witnessing a growth in its application in a wide range of The friction stir welding (FSW) process is witnessing a growth in a wide range of industrial applications due the minimal governing parameters and many other advantages as a solid state welding compared to the commonly used fusion welding process. However, tensile residual stress remains to be significant concern due to its extensive clamping and stirring process which can lead to lower fatigue resistance particularly in structures subjected to fluctuating loads. Up to day, research dealing with fatigue enhancements methods for FSW is rarely found in literature. This novel study presents an unconventional method to optimize the governing process parameters of Pneumatic Impact Treatment (PIT) also known as one of the High Frequency Mechanical Impact (HFMI) techniques. The post weld treatment is aimed to enhance fatigue resistance of FSW butt joints. The experimental study was conducted for Aluminum alloy (AA 6061) plates with thickness of 6 mm under varied PIT parameters centered on the intender pin diameter, applied air pressure and hammering frequency. The investigation began with obtaining optimum parameters for single response by using conventional Taguchi method with L9 orthogonal array. Further, advanced optimization approach by means of Multi-objective Taguchi Method (MTM) attempts to consider the multiple quality features simultaneously which are hardness value and fatigue life cycle. The significant level of the PIT parameters was investigated by using analysis of variance (ANOVA). As the final results, the optimum value was acquired by calculating the total normalized quality loss (TNQL) and multi signal to noise ratio (MSNR). Subsequent confirmation test was conducted upon determination of the optimized PIT parameters

Methoden und Herausforderungen bei der numerischen Simulation des selektiven Laserschmelzens (SLM)

Additive Fertigungsverfahren stellen in den letzten Jahren einen Megatrend dar, da sich mit diesen Verfahren endkonturnahe Werkstücke mit hohem Materialausnutzungsgrad herstellen lassen. Die auch als 3D-Druck bekannt gewordenen additiven Fertigungsverfahren sind jedoch nicht auf die Prototypenfertigung aus Kunststoffen begrenzt. Beim selektiven Laserschmelzen werden metallische Werkstoffe im Pulverbettverfahren mittels Laserstrahl aufgeschmolzen und somit schichtweise aufgebaut. Das Verfahren findet bereits in der Luft- und Raumfahrt, der Medizintechnik, aber auch in der Automobilindustrie und im Maschinenbau Anwendung für Prototypen, Einzelanfertigungen oder Kleinstserien. Des Weiteren ermöglicht es auch die Herstellung von Werkstücken mit besonders hoher Komplexität, die mit spanenden Verfahren nicht herstellbar sind, und bietet dadurch neue Gestaltungsmöglichkeiten bei der Konstruktion. Innerhalb des Vortrags werden nach der Vorstellung des Verfahrens verschiedene Methoden zur numerischen Simulation des selektiven Laserschmelzens von Edelstahl (1.4404) am Beispiel der kommerziellen Software Simufact Additive erläutert. Dazu werden der mechanische und thermo-mechanische Lösungsansatz betrachtet sowie die Methode zur Kalibrierung der Simulationen erläutert. Die Erläuterung eines voll transienten thermo-mechanischen Ansatzes erfolgt unter Verwendung der Software MSC Marc. Des Weiteren wird der Einfluss der Orientierung des Werkstücks im Herstellungsprozess auf resultierende Spannungen, Verzug sowie mechanische Eigenschaften analysiert und mit experimentellen Untersuchungen untersetzt

Methoden und Herausforderungen bei der numerischen Simulation des selektiven Laserschmelzens (SLM)

Additive Fertigungsverfahren stellen in den letzten Jahren einen Megatrend dar, da sich mit diesen Verfahren endkonturnahe Werkstücke mit hohem Materialausnutzungsgrad herstellen lassen. Die auch als 3D-Druck bekannt gewordenen additiven Fertigungsverfahren sind jedoch nicht auf die Prototypenfertigung aus Kunststoffen begrenzt. Beim selektiven Laserschmelzen werden metallische Werkstoffe im Pulverbettverfahren mittels Laserstrahl aufgeschmolzen und somit schichtweise aufgebaut. Das Verfahren findet bereits in der Luft- und Raumfahrt, der Medizintechnik, aber auch in der Automobilindustrie und im Maschinenbau Anwendung für Prototypen, Einzelanfertigungen oder Kleinstserien. Des Weiteren ermöglicht es auch die Herstellung von Werkstücken mit besonders hoher Komplexität, die mit spanenden Verfahren nicht herstellbar sind, und bietet dadurch neue Gestaltungsmöglichkeiten bei der Konstruktion. Innerhalb des Vortrags werden nach der Vorstellung des Verfahrens verschiedene Methoden zur numerischen Simulation des selektiven Laserschmelzens von Edelstahl (1.4404) am Beispiel der kommerziellen Software Simufact Additive erläutert. Dazu werden der mechanische und thermo-mechanische Lösungsansatz betrachtet sowie die Methode zur Kalibrierung der Simulationen erläutert. Die Erläuterung eines voll transienten thermo-mechanischen Ansatzes erfolgt unter Verwendung der Software MSC Marc. Des Weiteren wird der Einfluss der Orientierung des Werkstücks im Herstellungsprozess auf resultierende Spannungen, Verzug sowie mechanische Eigenschaften analysiert und mit experimentellen Untersuchungen untersetzt