Friction Stir Welding and Processing XII: FSW of High Melting Temperature Materials
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Yuri Hovanski, Brigham Young University; Yutaka Sato, Tohoku University; Piyush Upadhyay, Pacific Northwest National Laboratory; Anton Naumov, Peter The Great St. Petersburg Polytechnic University; Nilesh Kumar, University of Alabama, Tuscaloosa
Tuesday 2:30 PM
March 21, 2023
Room: 29A
Location: SDCC
Session Chair: Kenneth Ross, Pacific Northwest National Laboratory; Arnold Wright, Bond Technologies
2:30 PM Invited
Advances in Steel FSW: Stephen Cater1; Jonathan Peter Martin1; 1TWI
Friction stir welding has been widely used for the fabrication of safety critical aluminium structures in the aerospace, road, rail and marine transport industries since its invention in 1991. Due to its ability to make high strength, tough, fatigue resistant welds with very low distortion, and the fact that the process can work underwater, considerable interest has been shown over many years in transferring the technology to the welding of steel. The difficulties in developing tools able to stir steel at the elevated temperatures required, in excess of 900 C, are now being overcome and the process is being developed for welding steel with an initial focus on marine applications. This paper discusses the technical advances being made at TWI and outlines the newly begun EU project “RESURGAM” which looks to develop the process for both the construction and repair of ships.
2:50 PM Invited
Assessing Manufacturability of the Oxide Dispersion Strengthened (ODS) 14YWT Alloy Fuel Cladding Tube using SolidStirTM Technology: Shubhrodev Bhowmik1; Pranshul Varshney1; Osman El Atwani2; Stuart Maloy3; Kumar Kandasamy4; Nilesh Kumar1; 1University of Alabama, Tuscaloosa; 2Los Alamos National Lab; 3Pacific Northwest National Lab; 4Enabled Engineering
The 14YWT (Fe–14Cr–3W–0.4Ti–0.3Y2O3 (wt.%)) alloy is a potential candidate material for fabricating fuel cladding tube and other structural components to be used in next-generation advanced nuclear reactors. Due to inherent limitations of current processing routes, this research explored a new variant of friction stir processing, commercially referred to as SolidStirTM Extrusion (patent pending) technology from Enabled Engineering to consolidate and extrude 14YWT powder into a fuel cladding tube. Several single layer and multiple layer consolidation experiments were carried out in an Inconel 625 die to determine the suitable processing parameters for SolidStir extrusion of the 14YWT alloy cladding tube. With these processing parameters, a 16-18 mm long tube of the 14YWT alloy with no visible defects was successfully extruded using this novel technology. Microstructural characterization results obtained using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy will be presented.
3:10 PM
Friction Stir Welding of Nickel-based Superalloys: Mageshwari Komarasamy1; Christopher Smith1; Woongjo Choi1; Jens Darsell1; Glenn Grant1; 1Pacific Northwest National Laboratory
Advanced ultra-supercritical (A-USC) steam plants are designed to operate at high temperatures and pressures due to the necessity for higher operational efficiency. The extreme operating conditions of A-USC requires the deployment of precipitation strengthened Ni-base alloys that exhibit elevated temperature strength and good fabricability. In the current study, friction stir welding, a solid-state joining technique was implemented on Haynes 282 (a precipitation strengthened nickel-based superalloy). Cross-weld tensile and creep tests, and electron microscopy characterization have led to the following observations. In post-weld heat treated condition, 100% joint efficiency was obtained. Under 760°C and 871°C thermal exposure, the welded region exhibited excellent thermal stability and higher strength as compared to the base material. Creep properties of the weld was similar to the base material under tested stress values. The microstructure of the creep failed sample and the creep failure mechanisms were investigated in detail.
3:30 PM
Friction Stir Welding of Thick Steel Plate by Silicon Nitride Tool: Yoshiaki Morisada1; Masakazu Mori2; Yasushi Hara3; Yusuke Katsu3; Hidetoshi Fujii1; 1Osaka University; 2Ryukoku University; 3NGK Spark Plug Co, LTD
Friction stir welding (FSW) is being increasingly attractive in welding steels on account of the high-quality weld formation and excellent weld properties. Although various materials such as polycrystalline cubic boron nitride (PCBN), tungsten alloys and Ir alloys are used as tool material, it is difficult to decrease the tool price because of the rare compositional elements and/or expensive production process. Among ceramic materials, silicon nitride is one of the best candidates as tool material due to its excellent fracture toughness and low cost. However, silicon nitride tool has been mainly used for only thin steel plates with a thickness of 3 mm or less. In this study, we investigated the ability of a silicon nitride FSW tool to weld a low carbon thick plate with a thickness of 6～15 mm. Additionally, effect of the FSW condition on the tool wear and tool life were clarified.
3:50 PM Break
4:10 PM
Friction Stir Welding of Steel with Steel Tool: Takuya Miura1; Yoshiaki Morisada1; Kohsaku Ushioda1; Hidetoshi Fujii1; 1Osaka University
In friction stir welding (FSW) of steels, extraordinary durability is required for tools at high temperature during the welding. Therefore, high-melting point metals and ceramics are usually used as tool materials for FSW of steels; however, some problems still remain in cost and durability. On the other hand, if the tool temperature can be kept lower than that of the material around tool during welding, it can be expected that a relatively inexpensive steel tool can be applied as the tool material for FSW of steels. Therefore, in this study, to demonstrate a possibility of the FSW of steel using a steel tool, cold-rolled steel sheets were FSWed using a FSW tool made of tool steel (JIS SKD61), which is cooled by flowing water through the center channel. It is noteworthy that the steel sheets were successfully joined without tool failure.
4:30 PM
Post-Irradiation Examination of High-dose Ion Irradiated Friction Stir Welding (FSW) MA956 ODS Alloy: Yu Lu1; Ramprashad Prabhakaran2; Yaqiao Wu1; Megha Dubey1; Lin Shao3; 1Boise State University; 2Pacific Northwest National Laboratory; 3Texas A&M University
Oxide dispersion strengthened (ODS) alloys are candidate cladding materials for the next generation advanced nuclear reactors due to their excellent resistance to irradiation damage and superior mechanical properties. However, conventional weld method would lead to agglomeration of fine oxide particles and result in loss of strength. Friction stir welding (FSW) is a solid-state joining technique that does not require melting at the joint interface. FSW was used to weld MA956 in a bead-on-plate configuration and higher weld efficiency was obtained. In this study, parent and friction stir welded MA956 were ion irradiated to different doses (2.5, 50 and 100 dpa) with Fe2+ at 320°C. Post-irradiation characterizations were performed using scanning transmission electron microscopy, atom probe tomography and nanoindentation techniques. With combination of these techniques, the microstructure evolution and mechanical property change of parent and friction stir welded MA956 after irradiation were examined and compared in detail.
4:50 PM Invited
Effect of Locally Beta-transformed Area on Fatigue Crack Propagation Resistance in a FSWed Ti-6Al-4V: Masakazu Okazaki1; Satoshi Hirano2; 1Niigata Institute of Technology; 2Hitachi Research Lab.
There are growing interest and potential application of FSW in fabricating titanium components in aerospace and space components. In the case of near alpha Ti-6Al-4V (Ti-6-4) alloy, a locally transformed area from hcp to beta structure are sometimes formed relating to the hot spot in temperature during the FSW process. The purposes of this research are to get basic knowledge on the above questions or dilemma, via exploration on the role of microstructure. Here special attention has been paid to the effect of the local beta-transformed microstructures. The experimental study demonstrated that the local fatigue crack propagation (FCP) rates in the stirred zone and near the interfacial zone were higher than those in the base metal by a few times. The local fatigue crack threshold level was also significantly affected. The local beta-transformed microstructure had undesirable effect on the FCP, not only in the longitudinal but in the transverse cracks.