This study conducts an experimental investigation to explore the impact of the Traverse speed of a tool on the tensile strength and micro-structural peculiarities of joints attained during friction stir welding of Cu alloy namely CDA 101 at plates. In this process, other parameters including spinning speed of tool (1100 rpm) and downward force (6 kN) were kept constant. A tool with a cylindrical tapered pin geometry was made to Traverse at varying speeds, from 20 mm/min to 45 mm/min. It was observed that the CDA 101 joints fabricated at 20 mm/min were entirely free of flaws, while the joints fabricated at other Traverse speeds of the tool were featured several weld flaws. Grains in the center of the stir zone of the joints obtained at 20 mm/min were uniformly distributed and homogeneous due to the significant volume of frictional heat and sufficient stirring force. The highest tensile strength of 200. 65 MPa (nearly 85. 38% of base metal) was exhibited by the joint attained at 20 mm/min.

In this study, thermo-mechanical stability of two-pass constrained groove pressing (CGP) AA1050 sheets towards friction stir welding (FSW) employing hybrid powder (%50vol. micrometric graphite powder+%50vol. α-Al2O3 nanoparticles) was investigated by examining its microstructural evolutions and mechanical properties. FSW was carried out via different process variables in order to reach the highest ultimate mechanical properties of joints. The welding variables employed in this study were single-pass and multi-pass FSW, and different rotation speed to Traverse speed ratios (ω/v) were. In order to appraise the powder effect on mechanical properties in the fabricated hybrid metal matrix composite (HMMC), some CGPed sheets were also welded with no powder. Besides optical microscopy and field emission scanning electron microscopy (FESEM) observations, Vickers microhardness and transverse tensile tests were conducted to examine mechanical properties of the weld zone. It was revealed that the effect of graphite powder as a solid lubricant was substantially influenced by the welding variables. More precisely, by employing graphite powder during the FSW, the peak temperature decreased to 224 ℃, while the peak temperature of 489 ℃ was resulted by welding without any powder. Thus, the thermo-mechanical stability of CGPed aluminum and their mechanical properties were enhanced. On the other hand, graphite powder can be responsible for mechanical properties drop due to deteriorating material flow. In addition, different strengthening mechanisms, including grain boundary Zener-pinning and particulate stimulated nucleation (PSN) mechanism, were provided and governed by both powders. However, increasing the ω/v ratio was a practical approach to obtain uniform powder distribution, and consequently, to attain ultimate mechanical properties. Moreover, weld soundness was perceived to be achievable by increasing the number of FSW passes due to eliminating the cavities and improved material flow, resulting in an ultimate tensile strength of 101 MPa, as an optimum efficiency of ~ %80, in three-pass FSW at ω/v=70.

In this research, the influence of friction stir welding parameters (tool Traverse speed ranging from 50 to 150 mm/min, and tool rotational speed ranging from 300 to 1100 rpm) was investigated on the microstructure and mechanical properties of AA5052 aluminum/PP-Z30S polypropylene joint. Results showed that joint formation was accompanied by the formation of mechanical locks in the shape of anchor-like aluminum pieces. Decreasing the heat input (either by increasing the tool Traverse speed or decreasing the tool rotational speed) resulted in the formation of larger anchors. The results of tensile-shear test showed that increasing the tool Traverse speed from 50 to 100 mm/min led to an enhancement in the fracture load (by ~10%), while at higher Traverse speeds, the fracture load decreased (from 235 to 181 N) due to the formation of defects and voids at the joint interface. An increase in the tool rotational speed from 300 to 900 rpm resulted in a superior fracture load (by 70%) due to the formation of anchors perpendicular to the polymer surface with greater penetration depth.

In spite of increasingly utilizing high speed machining (HSM), the conventional tool path generation methods which are based on linear/circular blocks by applying standard strategies like parallel, z constant and Iso are usually employed in practice. Even though these tool-paths are employed by non-linear interpolators they have inherent limitations for HSM applications. This paper presents a new method for tool path generation in terms of NURBS. In order to increase the continuity of machining in HSM, a helical topology tool path in terms of NURBS is developed. This method reduces the number of CNC blocks up to five times. This algorithm creates a 2D-horizontal guide plane by offsetting the contour edges of the design surface. After that the inside offset of the contour is generated at a computed distance and then the contour and all its offsets are projected on the CL-surface. Finally, the tool-paths are approximated with NURBS approximation algorithm. The algorithm is designed to minimize the number of control points. An example of proposed approach consisting the comparison of the conventional method and verification is given.

Friction-Stir Processing (FSP) was applied on AA1050 Aluminum Alloy (AA) to find the highest mechanical properties among 28 combinations of the rotational and Traverse speed (800-2000 rpm and 50-200 mm.min-1) and four different tool probe shapes (threaded, columnar, square and triangle). To this aim, the AA standard sheet went through a single pass of FSP. The 1600 rpm and 100 mm.min-1 with threaded tool probe was chosen as the best combination of rotational and Traverse speed. Grain size at the Stirred Zone (SZ) was studied using Optical Microscopy (OM). The results showed that the SZ’s grain size was refined from 30 μm down to about 12 μm due to dynamic recrystallization during FSP. The processed sample exhibited improved hardness, yield stress, ultimate tensile strength, elongation up to 65, 80, 66, and 14%, respectively, compared to the annealed AA sample. Studying fractographic features by OM and field emission scanning electron microscope (FESEM) revealed a dominantly ductile fracture behavior.

In this study, the effects of friction stir welding parameters on the formation of intennetallic compounds, defects and tensile strength of AAII00 aluminum joints A441 AISI steel were studied. Thick Intermetallic compound formed at high tool rotational speed and low Traverse welding speed. iChemical compositions of these components were Al6Fe2 and Al6Fe that formed in joints interfaces. Tunnel defects were main voids that formed in the stir zone. Due to improper heat generation in lower rotational speeds, this void made in low rotational tool speeds and these voids vanished with increasing the frictional heat. Frictional heat increased by tool plunge depth and stir zone void became smaller. By controlling mechanical parameters of the process strongest joint produced in 800rpm tool speed, 63 mm/min Traverse speed and 0.2 mm tool plunge depth. This joint had 90% of the aluminum base metal strength.

Friction stir welded butt joints were performed on sheets made of AA2024-T351 aluminum alloy at tool rotational speeds of 400, 630, 800 rpm and Traverse speeds of 8, 16, 25 mm/min. The fatigue crack propagation rate was investigated according to standard ASTM-E647 in CT specimens. FE simulation of FSW process was implemented for different welding conditions and next the fatigue crack propagation was simulated using XFEM method. In this analysis, to assess the damage in the joints, maximum stress criterion is used. The maximum principal stress in element was the fracture criterion. Numerical results are in good agreement with the experiments so the simulation is reliable. The obtained results show that the tool rotational and Traverse speed affect the fatigues crack growth rate. For all welded specimens crack propagation rate was slower than that of the base metal for low values of DK (DK£13 MPa) but is much faster at high values of DK. Furthermore fatigue properties of specimens that were welded with lower speeds are better than base metal and increase in rotational or Traverse speeds of the tool will increase the crack propagation rate of the welded specimens.

Selecting tool materials, tool sizes and determining the cutting parameters presents a great challenge in machining operations especially in high speed machining processes. In this study effect of feed rate which is one of the important machining parameters and tool size on tool life in high speed machining of Ti-6Al-4V alloy were investigated. Fixed cutting speed of 200 m/min, feed rate of 0.03 and 0.06 mm/tooth together with axial cutting depth of cut 5.0 mm, and radial cutting depth of cut 1.5 mm were employed as the cutting parameters. TiAlN+TiN coated tungsten cemented carbide insert in two different sizes was used during machining operations. Flank wear land measurement was taken by using a toolmakers’ microscope and recorded accordingly throughout the machining processes. The results showed during the machining employing both feed rate and using smaller tool size chipping occurred on the tool nose along with gradual tool flank wear. Also by increasing the feed rates utilizing the smaller size of tool highly affected tool life compared to employing the larger one during the high speed machining operations. Reducing the feed rate by 50 percent increased the tool life of smaller tool size by 200 percent.

Friction Stir Welding is one of the solid-state processes and today it has been used to join different types of materials. Friction stir welding does not have many problems and limitations due to melting and solidification of weld metal and by controlling its variables, the microstructure and desired mechanical properties can be achieved at the joint. Recently, in most industrial areas, due to its lightness and energy saving, much attention has been paid to the joining of aluminum alloys. The present study investigates the microstructure and evaluation of mechanical properties of friction stir welding in AA2024 and AA6061butt welds. A cylindrical threaded tool was used to join 5 mm thick plates at rotational speeds of 800, 1000 and 1200 rpm and Traverse speeds of 30, 50, 70, 90 and 110 mm / min. In order to perform the necessary investigations, metallurgical observations were performed by optical microscope and scanning electron microscope equipped with a chemical analysis system of the elements, as well as mechanical tests of tensile strength and micro hardness. The results showed that the difference between the two alloys causes hardness variations in the nugget zone and a large hardness drop at the transition between the zone composed of both alloys and the 6061 zone. By increasing the Traverse speed from 30 to 110 mm / min at constant rotational speeds of 800, 1000 and 1200 rpm, due to reduced input heat, the grain size decreases and the hardness and strength increase. Also, the highest tensile strengths and hardness were 221. 6 Mpa and 111. 05 Vickers, respectively, for a sample welded at a rotational speed of 1000 rpm and a Traverse speed of 110 mm / min.