Wear Inducing Phase Transformation of Plasma Transfer Arc Coated Tools during Friction Stir Welding with Al Alloy (original) (raw)
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Wear of potential tool materials for aluminium alloys friction stir welding at weld temperatures
Proceedings of the Estonian Academy of Sciences, 2019
Friction stir welding is a solid-state joining process that uses a non-consumable tool to join materials by mixing them mechanically in the weld area instead of melting them. The high-quality friction stir welding (FSW) process temperatures are in the range of 400-500 °C. Adhesive wear is suggested to be the main wear mechanism for the FSW tool. Adhesive wear testing should be performed at the weld temperature or close to the welding process temperatures for better simulation of real-life FSW tool wearing conditions. Adhesive wear tests of three FSW tool materials, WC-Co and TiC based with NiMo and FeCr binders at temperatures of 70 °C (low) and 400 °C (high) were performed by turning aluminium alloy AW6082-T6. The higher temperature in the cutting zone was achieved by increasing the cutting speed. To measure the temperature at the interface of the cutting tool and the workpiece, a novel method based on the thermoelectric effect was used. The wear was determined as the change of the geometry of the cutting edges of the tool. Microscopic investigations were performed by using scanning electron microscopy. The distribution of chemical elements and the chemical composition of the tool cutting edge were analysed by energy dispersive X-ray spectroscopy. The TiC-based cermets (TiC-NiMo and TiC-FeCr) demonstrated superiority over WC-Co cemented carbide at both low (70 °C) and high (400 °C) temperatures. The highest wear performance at the low temperature was shown by the Fe-alloy bonded composite TiC-FeCr while at the high temperature the Ni-alloy bonded cermet TiC-NiMo had the highest wear performance.
2015
A Simple Method for Evaluating Wear in Different Grades of Tooling Applied to Friction Stir Spot Welding Kirtis Frankland Kennard School of Technology, BYU Master of Science In this study tools consisting of a 5mm cylindrical pin and a 12mm shoulder held by a simple tool holder were used to compare the wear of 11 tooling materials. The objective was to determine if using these tools in a spot welding configuration to simulate friction stir welding could differentiate the potential performance of tooling materials. All tools were made of varying percentages of polycrystalline cubic boron nitride (PCBN), tungsten (W) and rhenium (Re). The materials are referred to herein as GV1, GV2, G1, G2, G3, G4, G5, G6, G7, G8 and G9. The tools were run to 205 welds if they did not fracture first. The grades averaged the following quantities of welds before fracture failure GV-1:0; GV-2:200; G1:82; G2:204; G3:205; G4:205; G5:96; G7:102.73; G8:21.2; G9:38.5. Of the tools that ran the full 205 welds...
In this work, cemented carbides with different cobalt content were developed by using medium and ultrafine tungsten carbide grains. The GGI, (Cr3C2), was added in small amount (0.5 wt. %) to restrict the grain growth. The effect of particle size, reinforcement content and sintering temperature on metallography, densification and mechanical properties is investigated. At 1680 ºC, Co phase was uniformly distributed at WC interface by particle rearrangement and resulted in fully dense microstructure. The fine particle enhanced the sintering rate due to large specific surface area and surface energy. The developed tool was used to join 4 mm thick high strength low alloy steel plates without severe wear and degradation of the tool. Tool oxidation and interface degradation associated to extreme tribological welding condition is observed.
Journal of Materials Engineering and Performance, 2013
Friction stir welding (FSW) is the preferred joining method for metal-matrix composites (MMCs). As a solid-state process, it precludes formation of the intermetallic precipitates responsible for degradation of mechanical properties in fusion welds of MMCs. The major barrier to FSW of MMCs is the rapid and severe wear of the welding pin tool, a consequence of prolonged contact between the tool and the harder reinforcements which give the material its enhanced strength. This study evaluates the effectiveness of harder tool materials to combat wear in the FSW of MMCs. The tool materials considered are O1 steel, cemented carbide (WC-Co) of the micrograin and submicrograin varieties, and WC-Co coated with diamond. The challenges which accompany the application of harder tool materials and diamond coatings in FSW are also discussed. This study represents the first use of diamond-coated tools in FSW and the first comparative evaluation of tool materials for this application.
IOP Conference Series: Materials Science and Engineering
Aluminium alloys are difficult to weld together under the standard welding techniques. Among the all welding processes, friction stir welding has proved its importance in joining of different aluminium grades. In the present work, joining of two dissimilar aluminium alloys AA6101 & AA6351 has been carried out by friction stir welding process with different rotational speeds and a constant welding speed. Radiography study of the weld joint explains the defects present in the welded zone. A good quality weld zone is due to the proper selection of tool rotational speed as it helps in uniform mixing. The micro hardness test and wear behaviour were studied for the weld zone. The higher tool rotational speed of FSW reduces the wear volume due the increase in hardness of the weld zone. The SEM analysis shows the different worn out behaviour of the weld surfaces. Better burr free surfaces are obtained with the weld zones welded at high rotational speed.
Materials
The study presents the results of examinations of wear in tools made of 1.2344 steel without and with an anti-wear coating in the process of welding overlap joints of sheet metal made of 7075-T6 aluminum alloy using friction stir welding (FSW) technology. A commercial anti-wear AlCrN coating (Balinit® Alcrona Pro by Oerlikon Balzers Coating Poland Sp. z o.o., Polkowice, Poland) was examined, applied using physical vapor deposition (PVD) and used to improve tool life in metalworking processes. Wear tests for the tools were conducted in industrial conditions at specific parameters of the friction stir welding process. Tool wear was evaluated through examination of the tool working surface. The results of the static tensile strength tests and metallographic examinations of the joints were used to evaluate the effect of tool wear and the coating impact on joint quality. The results obtained in the study show that the tool made of 1.2344 steel was intensively worn after the welding of a ...
Friction stir welding (FSW) is a relatively new solid state joining process that uses a non-consumable tool to join two different material without melting the workpiece material. Heat is generated by friction between the rotating tool and the workpiece material. This joining process is energy efficient, environment friendly and versatile. Friction stir welding (FSW) was developed for microstructural modification of metallic material. This review article provides an overview of effect of FSW/FSP mechanism responsible for the formation of weld, microstructure refinement, wear of FSW tool and mechanical properties. This review conclude with recommendations for future research direction.
Experimental Techniques, 2009
I n this study, Al7075-T6 material has been joined by friction stir welding (FSW) and then burnishing process has been applied to the welded region. The effects of burnishing process parameters such as feed rate, compression force, revolution, and pass number on surface roughness, surface hardness, and weld strength have been experimentally investigated. The effects of these parameters on surface roughness and surface hardness of the welded region have been determined. Optimum conditions of surface roughness and surface hardness values have been obtained. It is observed that higher pass number has a negative effect on surface roughness. The results suggest that surface roughness of the workpiece improves and surface hardness increases provided suitable burnishing conditions are chosen. The mechanical properties were evaluated through uniaxial tensile tests, and tensile strength experiments have been applied to the burnished test specimens. Results have shown that burnishing process negatively affected material strength although it improves surface roughness positively.
Wear behavior of ceramic-metal composites as tool materials for FSW of stainless steel
BALTTRIB, 2019
Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join materials by mixing them mechanically in the weld area instead of melting the materials. The temperatures of the high-quality FSW process for stainless steels are above 1000˚C. The main wear mechanism for a FSW tool in the case of stainless steels is diffusion controlled wear. In our study, wear and diffusion tests were performed at the temperature close to the welding process for better physical simulation of real-life FSW tool wear conditions by turning stainless steel AISI304 at high speed. Tool materials such as WC-Co cemented carbides and TiC-based cermets with different binder composition and fraction were used. The temperature required in the cutting zone was achieved by increasing the cutting speed. To measure the temperature at the interface of the cutting tool and the workpiece, the method based on the thermoelectric effect was used. The wear was determined as the change of the geometry of the cutting edges of the tool. Microscopic investigations were performed using scanning electron microscopy. The diffusion mechanism was studied using the energy dispersive X-ray spectroscopy (EDS). TiC-based cermets with nickel based binder TiC-NiMo demonstrated superiority over WC-Co cemented carbides and TiC-based Fe-alloys bonded cermets TiC-FeNi and TiC-FeCr.
Journal of Materials Engineering and Performance, 2019
In the present study, dissimilar friction stir welding was carried out between stainless steel (UNS S30400) and mild steel (UNS G10080) plates of 4 mm thickness using a tungsten carbide tool. The influence of tool rotational speeds (600, 875 rpm) and tool offsets (0.6, 1.2 mm) on mechanical properties, i.e., hardness, tensile strength, and impact toughness of welded joints was investigated. Maximum tensile strength of the joint was about 107.6% of the mild steel under rotational speed of 875 rpm and tool offset of 1.2 mm. The maximum hardness reached in the stir zone was about 281 HV 0.5 due to the phase transformations and grain refinement. CharpyÕs notch toughness of the welded joints was observed lower than the base materials. The microstructural characterizations were carried by using an optical microscope, and FESEM-EDS analysis which revealed the complex material mixing and material movement during the welding. Tungsten-rich bands were observed in the weld micrograph especially toward the advancing side. During this study, various wear mechanisms like oxidation wear, abrasive wear, and adhesion wear were responsible for the degradation of tungsten carbide tool.