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The friction spot welding (FSpW) method was used to weld 2198-T8 Al-Li alloy at rotational speeds of 500 rpm, 1000 rpm, and 1800 rpm. It was shown that the grains in the FSpW joints were transformed from "pancake" grains to fine equiaxed grains by the heat input of welding, and the reinforcing phases of S' and θ were all redissolved into the Al matrix. This leads to a decrease in the tensile strength of the FsPW joint compared to the base material and a change in the fracture mechanism from mixed ductile-brittle fracture to ductile fracture. Finally, the tensile properties of the welded joint depend on the size and morphology of the grains and their dislocation density. At the rotational speed setting of 1000 rpm in this paper, the mechanical properties of welded joints consisting of fine and uniformly distributed equiaxed grains are best. Therefore, a reasonable set of the rotational speed of FSpW can improve the mechanical properties of the welded joints of 2198-T8 Al-Li alloy. [ABSTRACT FROM AUTHOR]

Aluminium metal matrix surface composites are gaining more attention in industries such as aerospace, marine and defence, due to the improved hardness, strength, ductility and better resistance to corrosion. In this study, Al/Ni–40Fe–10Ti surface composites were fabricated using friction stir processing (FSP) and the effect of tool rotational speed and transverse speed on the microstructural and mechanical properties was studied. Processing parameters chosen for the experiment are tool rotational speeds between 600 rpm and 1000 rpm, and transverse speeds between 70 mm/min and 210 mm/min. The results show that at a tool rotational speed of 1000 rpm and at transverse speeds of 140–210 mm/min, the hardness values were found to be improved significantly from 38 Hv of the base metal to 41 Hv of the friction stir processed (FSPed) surface. The tensile strength was also found to be improved in a sample produced at a rotational speed of 1000 rpm and transverse speed of 70 mm/min. Tool rotational speed and transverse speed have a greater influence on the mechanical properties of friction stirred process surface because of the high heat input generated in the weld region causing proper mixing and incorporation of the reinforcing Ni–40Fe–10Ti powder. [ABSTRACT FROM AUTHOR]

This paper deals with rotational moulding. The relationship between mould speed and wall thickness in the upper, middle and lower areas of rotational moulded parts is investigated. Young's modulus of moulded parts is determined via static tensile testing. A static compression test is performed to determine the maximum compressive force causing strain. The test is conducted on the wall of moulded parts, parallel to the main axis of rotation. Also, energy consumption in rotational moulding is investigated for different rotational speeds of the mould. Moulded parts are made of DOWLEX®2629UE linear low-density polyethylene (LLDPE). Experimental results are statistically analysed using STATISTICA 13. Non-parametric statistical tests are used for results analysis. The ANOVA method is employed to determine if there are any significant differences between obtained results. The statistical tests show that the range is much narrower for a speed ratio of 4:1. The narrowest range value is obtained for 12n3 rpm. The highest Young's modulus values are obtained for the parts moulded at 12n3 rpm (1263.33 MPa) and 16n4 rpm (1263.67 MPa). The highest maximum compressive force is obtained for the parts moulded at 12n3 rpm (10 400 N). An analysis of the results demonstrates that the part moulded at 12n3 rpm has the most advantageous properties. For this mould speed, the power consumption amounts to 8.28 kWh. Experimental results and statistical analyses demonstrate that mould speed affects both moulded part quality and energy consumption in the rotational moulding process. [ABSTRACT FROM AUTHOR]

In this study mechanical properties of friction stir welded AM60 magnesium alloy in existence and lacking of alumina nanoparticles were examined. Microscopical analysis revealed peak condition could be made in 1200 rpm rotational speed, not only in the absence of reinforcing alumina nanoparticles but also in the presence of them. Adverse effects of higher strains in lowering grain size and higher temperatures in grain growth should be considered. In the existence of alumina nanoparticles in the matrix some areas of low content aluminum formed besides of high aluminum content of intermetallic compounds regions. Higher hardness and ultimate tensile strength achieved in optimum 1200 rpm rotational speed not only with alumina nanoparticles but also in the absence of alumina nanoparticles condition. Higher stresses and therefore lower agglomerated alumina nanoparticles resulted with increasing rotational speed. With alumina nanoparticles in matrix, lower grain size, higher hardness and higher ultimate tensile strength was attained.

Friction stir welding equipment was used to weld 3 mm thick 6082 aluminum alloy and T2 copper, through metallurgical microscopy, hardness testings tensile testing, etc.explore the impacts of rotational speed on the organization and mechanical properties of welded joints. The results show that: Intermittent defects always exist at the interface of the joint, alternating distribution of aluminum and copper, and uniform mixing of the two materials; The microhardness distribution of the joint shows that the highest value appears in the weld core area with hardness of 210 HV, aluminum and copper side heat affected zone hardness have decreased, the lowest value for the aluminum side heat affected zone of about 60 H V; with the increase in speedy the tensile strength increases first and then decreases, when the spindle speed of 1 000 r/min, welding speed of 50 mm/min, the optimal weld forming effect, the tensile strength can reach 255 MPa, the fracture shape becomes more uniform with the increase of rotational speed, and the toughness nest increases, showing a stratified distribution. The fracture location is the aluminum copper bond, and the crack extends along the interface defect, showing mixed brittle ductile fracture at low speed and ductile fracture at high speed. [ABSTRACT FROM AUTHOR]

The friction spot welding (FSpW) method was used to weld 2198-T8 Al-Li alloy at rotational speeds of 500 rpm, 1000 rpm, and 1800 rpm. It was shown that the grains in the FSpW joints were transformed from “pancake” grains to fine equiaxed grains by the heat input of welding, and the reinforcing phases of S’ and θ were all redissolved into the Al matrix. This leads to a decrease in the tensile strength of the FsPW joint compared to the base material and a change in the fracture mechanism from mixed ductile-brittle fracture to ductile fracture. Finally, the tensile properties of the welded joint depend on the size and morphology of the grains and their dislocation density. At the rotational speed setting of 1000 rpm in this paper, the mechanical properties of welded joints consisting of fine and uniformly distributed equiaxed grains are best. Therefore, a reasonable set of the rotational speed of FSpW can improve the mechanical properties of the welded joints of 2198-T8 Al-Li alloy.

The influences of the pin geometry and rotational speed on the microstructure evolution and mechanical properties of the AA 5052-H112 FSSW joint were investigated. Results showed that hook height and fully bonded region (FBR) width were significantly dependent by both pin geometry and rotational speeds. Both pin geometry and tool rotational speed had an apparent influence on the strength of the weld. At 900 and 1400 rpm, the strength of welds prepared using a cylindrical pin was higher compared to that of a step pin. For the step pin, the cross-tension strength of the welds increased as rotational speed increased. For cylindrical pin, the tensile/shear and cross-tension loads achieved the maximum values of 3589 and 3419 N at 1400 rpm, respectively. Under tensile/shear loading, shear and tensile/shear fractures were observed. On the other hand, under cross-tension loading, two types of fracture modes, namely nugget debonding and nugget pull-out were detected.

This study examined the effect of AISI H13 steel-tapered tool on the dissimilar friction stir welding of 7075-T651 and 1200-H19 aluminium alloys. Three mechanical tests which include hardness, tensile strength and impact energy were conducted to study the effect of tilt angle, rotational and welding speeds on the weld integrities, 50 and 175 HV were respectively obtained as hardness values for AA1200- H19 and AA 7075- T651, the hardness values were measured for three selected welding speeds of 30, 60 and 90 mm/min representing low, medium and high at a constant rotational speed of 1500 rpm, a tool tilt angle of 2°.The hardness increases with the welding speed from 81.99 to 98.5 HV as the speed increased from 30 to 60 mm/min and dropped to 77 HV at 90 mm/min.The impact energy increased from 12.9 to 21.4 J with an increase in the welding speed from 30 to 60 mm/min and dropped to 5.4 J at 90 mm/min.The ultimate tensile strength (UTS) increased from 126.04 to 151.54 MPa with an increase in the welding speed from 30–60 mm/min and decreased from 151.54 to 128.37 MPa, the hardness at 1500 rpm and 60 mm/min increased from 70.22 to 98.58 HV with an increase in the tilt angle from 1- $${2^^\circ }$$, a further increase from 2–3 o reduced the hardness from 98.58 to 66 HV, UTS increased from 123.32 to 151.54 MPa as tilt angle increased from 1–2 ° and decreased to 122.2 MPa, the medium tilt angle of $${2^^\circ }$$,rotational and traverse speeds of 1500 rpm and 60 mm/min respectively gave the highest impact energy of 21.4 J.

This study examined the effect of AISI H13 steel-tapered tool on the dissimilar friction stir welding of 7075-T651 and 1200-H19 aluminium alloys. Three mechanical tests which include hardness, tensile strength and impact energy were conducted to study the effect of tilt angle, rotational and welding speeds on the weld integrities, 50 and 175 HV were respectively obtained as hardness values for AA1200- H19 and AA 7075- T651, the hardness values were measured for three selected welding speeds of 30, 60 and 90 mm/min representing low, medium and high at a constant rotational speed of 1500 rpm, a tool tilt angle of 2°.The hardness increases with the welding speed from 81.99 to 98.5 HV as the speed increased from 30 to 60 mm/min and dropped to 77 HV at 90 mm/min.The impact energy increased from 12.9 to 21.4 J with an increase in the welding speed from 30 to 60 mm/min and dropped to 5.4 J at 90 mm/min.The ultimate tensile strength (UTS) increased from 126.04 to 151.54 MPa with an increase in the welding speed from 30–60 mm/min and decreased from 151.54 to 128.37 MPa, the hardness at 1500 rpm and 60 mm/min increased from 70.22 to 98.58 HV with an increase in the tilt angle from 1- 2 ° , a further increase from 2–3 o reduced the hardness from 98.58 to 66 HV, UTS increased from 123.32 to 151.54 MPa as tilt angle increased from 1–2 ° and decreased to 122.2 MPa, the medium tilt angle of 2 ° ,rotational and traverse speeds of 1500 rpm and 60 mm/min respectively gave the highest impact energy of 21.4 J. [ABSTRACT FROM AUTHOR]

Inertia friction welding (IFW) is a solid‐state welding technology that avoids defects associated with molten weld processes; however, this process has rarely been used to weld ultrahigh‐strength steel (UHSS). Herein, 32CrMnSi2Ni6MoV UHSS is joined successfully via IFW. The mechanical properties after welding at different rotational speeds and the microstructure at 2800 rpm are studied in detail. The temperature distributions in the peripheral and central areas are modeled according to the temperature at the weld zone. The microstructural transformation is analyzed for different temperature intervals, and the microstructural characteristics of each interval correspond to the actual microstructure of the welded joint according to the temperature distribution model. High‐strength martensite forms at the weld zone, and the thermomechanical‐affected zone (TMAZ) in the peripheral region is divided into phase transformation zone, partial recrystallization zone, and plastic deformation zone, whereas the TMAZ in the central region includes only the partial recrystallization and pure plastic deformation zones. This difference is due to the higher frictional heat caused by the higher peripheral linear velocity during rotation. A tensile test shows that fracture occurs in the base metal (BM) region, and the yield strength, tensile strength, and elongation are 805 MPa, 1064 MPa, and 13.88%, respectively. [ABSTRACT FROM AUTHOR]

This study focuses on optimization of process parameters, which may result in improved mechanical properties of the friction stir weldments of AA2014-T651. Plain taper and threaded taper cylindrical tool pin profiles were used for the study. A set of experiments was conducted at different levels of tool rotational and weld speeds using two tool pin profiles. Mechanical properties such as tensile strength, yield strength, impact strength, percentage of elongation, and hardness were measured. Objective functions are developed for the five mechanical properties in terms of input parameters. The input parameters were optimized using teaching–learning-based optimization algorithm technique to improve mechanical properties. The teaching–learning-based optimization algorithm suggested three best combinations such as combination-I (940 r/min and 32 mm/min), combination-II (1100 r/min and 40 mm/min), and combination-III (1205 r/min and 45 mm/min). The optimization is also validated with experimental results. [ABSTRACT FROM AUTHOR]

SA213 T12 and SA213 F12 low alloy steel (LAS) tubes have been successfully welded using the rotary friction welding (RFW) process. The effect of the rotational speed on the microstructure and the mechanical properties of the joints has been studied. With increasing rotational speed, the tensile strength first increases to a certain extent and then decreases. Weld samples with the highest tensile strength (488 MPa) and maximum elongation (40.01%) are achieved at 60 rps. Using higher rotational speed (68 rpm) increased grain size in the heat-affected zone (HAZ). The samples joined at different rotational speeds failed in the HAZ. The hardness profile showed that the interface (IF) has a higher hardness than the other zones and base metal. The highest hardness of welded joints (198 HV) was observed in the 60 rps sample. The phase transformation of bainite and acicular ferrite at the weld interface was attributed to the high strength of the weld joint. Weld joint defects are observed at 55 rpm and 65 rpm, where high heat inputs and impurities at the weld interface cause incomplete metallurgical bonding, resulting in defects in the weld seam. [ABSTRACT FROM AUTHOR]

Submerged friction stir welding of magnesium alloys has not been well investigated to date. ME20M is an important lightweight magnesium (Mg) alloy with enhanced yield strength and heat resistance that merits further research. In this paper, submerged friction stir welding of the ME20M Mg alloy was carried out using different parameters for the underwater cooling. Defect-free weld joints were produced, and the macrostructure, microstructure, tensile properties, and hardness were investigated. The results show that by increasing the rotational speed, the grain size of the weld nugget increased, the tensile strength of the joint decreased, and the microhardness of the different weld zones decreased. The finest obtained grain size was about 3.5 µm in the weld nugget at a rotational speed of 1100 rpm. The highest tensile strength achieved was 183.2 MPa, which was ~ 76.32% of the base metal. The highest and lowest hardness values of the weld joint were obtained at rotational speeds of 1100 and 1600 rpm, respectively, in the weld nugget and heat-affected zones. [ABSTRACT FROM AUTHOR]

Abstract The properties and microstructure of friction stir processed AA 7075-T651 (Al-Zn-Mg-Cu) Aluminium alloy were studied using various tool designs. Trials were conducted on AA 5005-H34 with the aim of determining the most suitable FSP tool design out of the considered three different pin designs. Fully recrystallised fine microstructure and a defect free processed zone was achieved through the use of some of the FSP pin designs. For FSP 5005-H34 aluminium alloy substantial grain refinement was detected. The initial 192 µm pancake-like microstructure in the AA 5005-H34 base material was refined to 10–20 µm in the processed regions. Similarly, the grain size of around 50 µm in the base material was decreased to 4–10 µm in the processed regions of the FSP of 7075-T651 aluminium alloy. The traverse speed has a greater influence on the microhardness and mechanical properties, compared to the tool rotational speed. Microhardness and mechanical properties were improved as the traverse speed increased, due to the reduction in the precipitate-free zones at the grain boundaries. [ABSTRACT FROM AUTHOR]

Abstract In this work, magnetron sputtering deposition facility was performed to fabricate TiC/graphite-like carbon (denoted as GLC) composite films. The microstructure and element composition of the as-fabricated TiC/GLC composite films were analyzed by field emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Moreover, the influence of rotational speeds of specimen holder on microstructure, mechanical, and electrical properties of the as-prepared TiC/GLC composite films were systemically investigated. Results indicate that the microstructures of TiC/GLC composite films experience the transition from layered growth pattern to columnar growth pattern with increasing rotational speed. The transmission electron microscope characterizations show that multilayered microstructure was self-organized in the TiC/GLC composite film deposited at rotational speed of 5°/s. The TiC crystallite embedded in carbon networks composite structure dominates the films with other rotational speeds. The TiC/GLC film with multilayered structure has lower internal stress and higher adhesion to the substrate compared to composite structure. The mechanical and electrical measurement results demonstrate that the nano-hardness and conductivity are enhanced owing to formation of high content of hard and conductive TiC phase embed in the carbon networks nanostructure in TiC/GLC composite films. Meanwhile, the growth mechanisms of TiC/GLC composite films at different rotational speeds are also proposed. The excellently electrical and mechanical properties indicate that the GLC/TiC composite film possesses widespread potential as transducers for biosensors in biology and carbonaceous electrode materials. Graphical abstract Unlabelled Image Highlights • Influence of rotational speed on microstructure and properties of TiC/GLC films was discussed. • Multilayered and composite TiC/GLC films were obtained by adjusting rotational speed. • GLC/TiC films exhibited excellent mechanical and electrical properties. • The GLC/TiC film possesses potential as transducers and carbonaceous electrode materials. [ABSTRACT FROM AUTHOR]

In this study, the effect of tool rotational speed on mechanical properties of AA 6082-T6 aluminum alloy was investigated. Different welded joints were produced by using four rotational speed (500, 710, 1000 and 1400 rpm) and constant welding speed at 80 mm/min. Mechanical properties of the welded joints were evaluated by hardness measurement on the transverse section and tensile testing. The experimental results show that the tool rotational speed has a significant effect on weld mechanical properties of joints. [ABSTRACT FROM AUTHOR]

Samples of 6082-T6 aluminum alloy were welded by bobbin tool friction stir welding at different rotational speeds. The thermal cycles, microstructure, microhardness, and tensile properties of the specimens were investigated. The results show that the maximum temperature at the joint increases first and then decreases with increasing rotational speed, and the maximum temperature is 509 °C at 1000 r/min. The macromorphology of the cross-section of the joint is rectangular, and an ‘’S” line and gray-white texture can be observed. The stirred zone had much smaller equiaxed recrystallized grains. With increasing welding speed, the average grain size in the stirred zone region decreases. The microhardness distribution of the cross-section of all joints is W-shaped. When the rotational speed increases, the hardness of the heat-affected zone decreases gradually, and the hardness of the stirred zone increases. At 600 r/min, the strength is the lowest. The fracture location is between the stirred zone and the thermomechanically affected zone. When the rotational speed is increased, the fracture location is entirely located in the heat affected zone, and the fracture surface is dimple-like; the strength significantly increases and reaches a maximum at 800 r/min.

Refill friction stir spot welding (RFSSW) was successfully used to weld alclad 2024 aluminum alloy with different thicknesses. Effects of tool rotational speed on the weld formation, microstructure, and mechanical properties of the RFSSW welds were mainly discussed. Results show that keyhole is successfully refilled and welding defects such as flash, annular groove, and material adhesion can be observed. A bright contrast bonding ligament is found embedded in the weld and it is thicker in the center. Defects of hook, void, lack of mixing, and incomplete refilling can be found at the thermo-mechanically affected zone/stir zone (TMAZ/SZ) interface, which can be attributed to weak metallurgical bonding effect. With increasing the tool rotational speed, thickness of the bonding ligament decreases, grains in the SZ coarsen, hardness of the SZ decreases, and lap shear load of the welds decreases. When changing the rotating speed, impact strength shows rather complicated variation trend. [ABSTRACT FROM AUTHOR]

Friction stir processing is a solid state technique for partial modification of microstructures in surface layers of metals. Heat input is one of the efficient factors in this process which can vary the mechanical properties and the grains size even up to nano scale. In the present study, the effects of different rotational to traverse velocity ratio and also the circumstances of each one's effects on heat input were investigated during FSP of Mg alloys. Microstructure analyses were implemented in order to gain some concepts of heat input effects on the structures of the stirred zone. In the next step, the microhardness measurements were also calculated by a hall-petch type equation according to the grains size of the microstructures. The results indicate that increase in heat input leads to increase in grain size and decrease in hardness in the process zone. This phenomenon occurs because of complex interactions between dynamic recrystallization and grain growth during increasing heat input. The results also showed that there is always an optimum velocity ratio which disorder the balance, thereby maximizes the dynamic recrystallization and minimizes the grain growth in order to gain the minimum possible grain size in this process. [ABSTRACT FROM AUTHOR]

Friction stir welded Mg AZ31B alloy have been investigated. Friction stir welding (FSW) is carried out at different rotational speeds of 900 rpm, 1120 rpm, 1400 rpm and 1800 rpm and with change of tool materials such as High speed steel (HSS) and Stainless steel (SS) at a constant welding speed of 40 mm/min, tilt angle of 2.50 and axial force of 5 KN. It is observed In this study, the effect of tool material and rotational speed on microstructure and mechanical properties of that the joint fabricated using SS tool material at a rotational speed of 1120 rpm obtained higher mechanical properties as compared to those of 900 rpm, 1400 rpm and 1800 rpm and also to those of HSS material. [ABSTRACT FROM AUTHOR]

Friction welding is widely used as a mass production method in various industries. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed AISI 1021 steels. In this study, low alloy steel (AISI 1021) was welded under different welding parameters and afterwards the mechanical properties such as tensile strength, impact strength and hardness were experimentally determined. On the basis of the results obtained from the experimentation, the graphs were plotted. It is the strength of welded joints, which is fundamental property to the service reliability of the weldments and hence present work was undertaken to study the influence of axial pressure and rotational speed in friction welded joints. Axial pressure and rotational speed are the two major parameters which can influence the strength and hence the mechanical properties of the friction welded joints. Thus the axial pressure and rotational speed were taken as welding parameters, which reflect the mechanical properties. [ABSTRACT FROM AUTHOR]

In this article, effects of rotational speed on the microstructure and mechanical properties of friction stir-welded 7075-T6 Al alloys were investigated. Good correlation existed between the rotational speeds and weld properties. It was found that with increase in the rotational speed, higher pick temperatures and wider thickness of the heat-affected zone were obtained, and then grain coarsening, dissolution, and accumulation of hardening precipitates in grain boundaries. The average grain size of nugget increased from 6.8 to 8.9 µm, with increasing rotary speed from 600 to 1550 r/min. In addition, the best mechanical properties were obtained at moderate rotational speed of 825 r/min while ultimate tensile strength and elongation were 405 MPa and 6.1 per cent, respectively. Also, it was observed that at low welding speed of 60 mm/min, the weld properties are found to be dominated by the thermal cycle rather than the plastic deformation induced by tool, so as to make a reduction in hardness and strength of the weld when using higher rotational speeds. [ABSTRACT FROM AUTHOR]