Showing papers on "Friction stir processing published in 2004"

Microstructural modification of as-cast NiAl bronze by friction stir processing

Abstract: The application of friction stir processing (FSP) to a cast NiAl bronze (NAB) material is presented as a means for selective modification of the near-surface layers by converting as-cast microstructures to a wrought condition in the absence of macroscopic shape change. This may enable selective surface hardening of cast components. The complex physical metallurgy of the NAB is reviewed, and microstructure changes associated with FSP for a selected set of processing parameters are examined by optical microscopy (OM) and transmission electron microscopy (TEM) methods. Direct temperature measurement in the stir zone is infeasible and, so, these microstructure changes are used to estimate peak temperatures in the stir zone. The persistence of a Fe3Al phase (κii) indicates that peak temperatures are below the solvus for this phase, while the presence of transformation products of the β phase, including fine Widmanstatten α, bainite, and martensite, indicates that peak temperatures exceed the eutectoid temperature for the reaction β → α+κiii throughout the stir zone.

Evaluation of microstructure and superplasticity in friction stir processed 5083 Al alloy

Abstract: Friction stir processing (FSP) has been developed as a potential grain refinement technique. In the current study, a commercial 5083 Al alloy was friction stir processed with three combinations of FSP parameters. Fine-grained microstructures with average grain sizes of 3.5–8.5 μm were obtained. Tensile tests revealed that the maximum ductility of 590% was achieved at a strain rate of 3 × 10−3 s−1 and 530 °C in the 6.5-μm grain size FSP material, whereas for the material with 8.5-μm grain size, maximum ductility of 575% was achieved at a strain rate of 3 × 10-4 s−1 and 490 °C. The deformation mechanisms for both the materials were grain boundary sliding (m ~0.5). However, the 3.5-μm grain size material showed maximum ductility of 315% at 10-2 s−1 and 430 °C. The flow mechanism was solute-drag dislocation glide (m ~0.33). This study indicated that establishing a processing window is crucial for obtaining optimized microstructure for optimum superplasticity.

Crack repair using friction stir welding on materials including metal matrix composites, ferrous alloys, non-ferrous alloys, and superalloys

Abstract: A system and method of using friction stir welding and friction stir processing to perform crack repair or preventative maintenance of various materials and structures, wherein the structures include pipeline, ships, and nuclear reactor containment vessels, wherein the friction stir welding and processing can be performed on various materials including metal matrix composites, ferrous alloys, non-ferrous alloys, and superalloys, and wherein the friction stir welding and processing can be performed remotely and in harsh environments such as underwater or in the presence of radiation.

Superplastic Forming of 7475 Al Sheet after Friction Stir Processing (FSP)

Abstract: Since the invention of Friction Stir Welding (FSW) in 1991, an increasing number of successful applications have been found for this unique solid-state welding technique. More recently, attention has been given to utilizing the mechanics of friction stirring to thermo-mechanically modify the microstructure of aluminum alloys to create or enhance superplasticity. Until now, superplasticity induced by friction stir processing (FSP) has only been demonstrated in small samples and evaluated by hot tensile elongation testing. The present work describes what we believe to be the first biaxial testing and full size component superplastic forming of friction stir processed aluminum sheet. The remarkable formability demonstrated in these ‘first time’ trials is described in detail.

Friction stir processing of aluminum alloys

Abstract: OF THESIS FRICTION STIR PROCESSING OF ALUMINUM ALLOYS Friction stir processing (FSP) is one of the new and promising thermomechanical processing techniques that alters the microstructural and mechanical properties of the material in single pass to achieve maximum performance with low production cost in less time using a simple and inexpensive tool. Preliminary studies of different FS processed alloys report the processed zone to contain fine grained, homogeneous and equiaxed microstructure. Several studies have been conducted to optimize the process and relate various process parameters like rotational and translational speeds to resulting microstructure. But there is only a little data reported on the effect of the process parameters on the forces generated during processing, and the resulting microstructure of aluminum alloys especially AA5052 which is a potential superplastic alloy. In the present work, sheets of aluminum alloys were friction stir processed under various combinations of rotational and translational speeds. The processing forces were measured during the process and the resulting microstructure was analyzed using TEM. The results indicate that the processing forces and the microstructure evolved during FSP are sensitive to the rotational and translational speed. It is observed that the forces generated increase with the increasing rotational speed. The grain refinement was observed to vary directly with rotational speed and inversely with the translational speed. Also these forces generated were proportional to the grain refinement i.e., greater refinement of grains occurred at lower forces. Thus the choice of process parameters especially the rotational speed has a significant effect on the control and optimization of the process.

Friction stir processing for surface properties

Abstract: A surface of an article is heated and subjected to pressure by operation of a friction stir tool. The pressure of the face of the tool on the article surface, and the speed of rotation of the tool and of its progression along the surface of the article, are controlled to progressively hot-work a specified surface area. The face of the tool may be round and have a profiled, axially extending, smaller diameter pin for higher concentration of frictional heat and load and for plasticizing a surface layer of the workpiece. Such hot work may be applied for reducing surface porosity or for producing another change in the surface microstructure, or for effecting another change in surface material properties.

Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of Fusion Welded 304L Stainless Steel

Abstract: : A variation of FSW, friction stir processing (FSP), has been used to modify selected regions of materials to enhance specific properties while eliminating fusion welding defects such as porosity, cracking, and the cast microstructure. The combination of fusion welding defects and high tensile residual stresses caused by the solidification of the molten weld pool adversely affect the post weld service integrity. FSP has been demonstrated to eliminate many of these problems while at the same time improving the resulting properties. FSP has been utilized to locally process regions of arc weldments in 304L stainless steel to improve the service integrity. The cast microstructure and coarse delta-ferrite is replaced with a fine-grained wrought microstructure. This paper presents a preliminary processing window for FSP of 304L stainless steel, the resulting microstructure associated with this process window, along with considerations given to mechanical properties and corrosion.

Influence of process parameters on superplasticity of friction stir processed nugget in high strength Al – Cu – Li alloy

Abstract: A parametric study was carried out to evaluate the influence of friction stir processing (FSP) parameters (tool rotation speed and feed rate) on the superplasticity of the weld nugget. Dynamically recrystallised AA 2095 thin sheets with a fine grain size of 2 μm were welded using four feed rates and three rotational speeds. High temperature tensile testing was employed to understand the significance of the FSP parameters and to optimise the parameters for maximum elongation. The tool rotation speed was found to be the most decisive parameter for controlling superplastic behaviour. A strain rate sensitivity of 0·68 was measured for the highest rotational speed at the optimum superplastic forming (SPF) temperature of 495°C. A maximum percentage 'elongation to failure' of 550% was achieved for the sheets subjected to FSP at 1000 rev min−1 and 4·2 mm s−1, compared with 475% obtained for the base metal at the optimum SPF temperature and strain rate of 495°C and 10−3s−1, respectively.

Selective reinforcement of metallic bodies

Abstract: A method of making composite structural components including beams and other structural components involving incorporating a reinforcing segment into a metallic body by, for example, friction stir processing.

The Isothermal Deformation of Nickel Aluminum Bronze in Relation to the Friction Stir Processing

Abstract: : The extreme strain, strain rate and temperature gradients during Friction Stir Processing (FSP) render measurement of key parameters in the stir zone infeasible with common methods. The objective of this research was to separate the effects that temperature and deformation in an experimental study of the microstructure and mechanical properties of Ni-AL bronze (NAB). This was accomplished by subjecting as-cast NAB material to several isothermal annealing and quenching treatments as well as isothermal hot rolling processes. Sufficient material was generated to provide results and data for subsequent optical microscopy, tensile, & hardness tests. All results were then compared to similar data collected from previous works completed here at Naval Postgraduate School and with other DARPA FSP program participants. During the course of this work correlations were drawn between FSP material and the material subjected to isothermal hotworking, which may enhance our understanding of the roles that various FSP process parameters have on the microstructural transformation sequence within this material. The hot-rolling study conducted here suggests that FSP process parameters leading to severe deformation at temperatures between 950-1000 C in the NAB material provides high ductility (elongation approximately 28%) with moderate strengths.

A Microstructural and Mechanical Property Correlation of Friction Stir Processed Nickel Aluminum Bronze

Abstract: : Friction Stir Processing (FSP) is novel technique for localized modification of the surface layer of materials. FSP produces high local strains, strain rates and local temperatures that are 0.8 - 0.9 Tm, where Tm is the melting point. The processing enhances the microstructural and mechanical properties of materials through intense plastic deformation. This thesis examines the microstructure and tensile properties in FSP'ed Nickel Aluminum Propeller Bronze (NAB) as a function of position in the stir zone using a unique miniature tensile sample design. Test materials were single and multi-pass FSP runs from both 6 mm and 13 mm tools. Tensile ductility was observed to increase from 11 percent to more than 30 percent elongation to fracture at locations along the center of the stir zone. Yield and ultimate strengths also increased two-fold. These improved properties were associated with the formation of Widmanst tten Alpha and fine, equiaxed Alpha at peak temperatures of approximately 1000 C in these locations. Some locations in the heat affected zone (HAZ) or thermomechanically affected zone (TMAZ) exhibited ductilities below that of as-cast material. Such regions had microstructures that contained a dark-etching constituent formed by cooling after being heated to approximately 800 C.

Enhanced golf club performance via friction stir processing

Abstract: Friction stir processing (FSP) provides a hardened golf club face that more efficiently transfers momentum between the golf club and the ball, increasing the launch velocity so as to provide increased loft (for a given distance traveled by the ball). The FSP hardened face is also more resistant to wear so that the golf club provides more consistent performance and lasts longer. A practice club having a friction stir processed sweet spot on the face may enable the golfer to feel whether the ball has been hit by the sweet spot.

Manufacturing method of magnesium alloy stock for plastic working excellent in workability, and plastic working method and article of magnesium alloy stock

Abstract: PROBLEM TO BE SOLVED: To provide a method of manufacturing magnesium alloy stock, a method that enables workability to be improved regardless of the size and shape of the magnesium alloy stock while the stock has superior stability of crystalline particles as well as excellent workability. SOLUTION: The magnesium alloy stock 10 has a predetermined part 11 for plastic deformation. Using a tool 20 with a rotatable probe 22, the rotating probe 22 of the tool 20 is inserted in the predetermined deformation part 11 of the stock 10, with the probe 22 moved along the predetermined deformation part 11 relative to the stock 10. Consequently, the part of the stock 10 in contact with the probe 22 is softened by frictional heat and, simultaneously, the friction stir processing part 12 stirred by the probe 22 is formed into the predetermined deformation part 11. COPYRIGHT: (C)2004,JPO

Modeling of Thermal and Mechanical Effects During Friction Stir Processing of Nickel-Aluminum Bronze

Abstract: : Friction Stir Processing (FSP), although relatively simple in concept, results in an extremely complex thermomechanical treatment to the material being processed. Previous studies of FSP have shown that the process results in extremely high strain, strain rates and temperatures as well as gradients in strain, strain rate and temperature within a small volume of material. This thesis will study the effect of varying FSP parameters during the processing of Nickel-Aluminum- Bronze (NAB) propeller material. The modeling program CTH was used to define the relationship between tool rotation speed, traversing speed and the total power input to the material. The tool s mechanical power and the power generated by deformation of the material has been investigated. The modeling experiments were designed to gain an understanding of the relationship of process parameters, microstructure and mechanical properties, and to enhance our understanding of the flow patterns and thermal histories of the NAB material in the stir zone.

Method for forming desired non-planar configuration by friction stir forming tool, and method and apparatus for forming workpiece to desired non-planar configuration

Abstract: PROBLEM TO BE SOLVED: To provide an apparatus and method for forming a workpiece to a desired, non-planar configuration. SOLUTION: At least one friction stir forming tool, having a shoulder and a pin, is used to urge the workpiece to the desired configuration and friction stir form the workpiece. The forming tool can urge the workpiece against a contour surface of a die or a shoulder that is opposite the structural member from the tool. Thus, the forming tool plasticizes a portion of the workpiece and urges the workpiece to the desired configuration. In addition, the material properties of the workpiece can be improved by the friction stir processing. COPYRIGHT: (C)2005,JPO&NCIPI

Superplasticity in advanced materials : ICSAM 2003 : [8th International Conference on Superplasticity in Advanced Materials, 28-30 July 2003, St. Catherine's College, Oxford, UK]

Abstract: Plastic Deformation in Metals with Nanosized Grains: Atomistic Simulations and Experiments Modelling Grain Boundary Sliding from First Principles Multi-Scale Modeling of Nanocrystalline Materials Grain Boundary Sliding of 5(001) Twist Grain Boundary in Aluminium Bicrystal from First-Principles Calculations Assessment of Contribution of Intragranular Slip to Grain Boundary Sliding in Bicrystals Cooperative Grain Boundary Processes in Superplastic Flow Dynamics of Grain Boundary Networks in Superplasticity Comparison between 2D and 3D Characterisations of Damage Induced by Superplastic Deformation Dynamic Grain Growth in Superplastic and Non-Superplastic Aluminium Alloys Cavitation Behaviors in a Tetragonal Zirconia Polycrystal Subjected to Superplastic Deformations Measured by SANS Method Simulation of Superplastic Deformation Based on a Mantle Model Dynamic Grain Growth in a Non-Superplastic Al-6Ni Alloy Physical Theory of Superplastic Flow in Spatially Extended Crystalline Systems Constitutive Equation for Superplastic Flow in Light Metallic Materials Grain-Size-Dependent Cooperative Grain-Boundary Sliding in Superplastic Deformation Multi-Scale Analysis of Failure during Superplastic Deformation The Measurement of Friction for Superplastic Forming of Ti-6Al-4V Finite Element Simulation for Superplastic Forming Process of Aluminium 5083 Design of SPF Dies Based on Advanced Material Behaviour Models Computer Simulation of Superplastic Forming in Restorative Dentistry The Influence of Pulsating Strain Rates on the Superplastic Deformation Behaviour of Al-Alloy AA5083 Investigated by Means of Cone Test Results of In-House Cone-Cup Testing of Low to High Temperature SPF-Alloys A Production System Using Ceramic Die Technology for Superplastic Forming Manufacturing of Shaped Forms from Stainless Steels with Superplastic Forming Constitutive Modeling of Deformation-Induced Anisotropy in Superplastic Materials Hyperbolic Sine Representation of a Constitutive Equation for Superplastic Forming Grade Inconel 718 Advances in Manufacturing Superplastically Formed and Diffusion Bonded Components Numerical Simulation of Superplastic Forming and its Microstructure Evolution ISO Proposal of a "Method for Evaluation of Tensile Properties of Metallic Superplastic Materials" On the Expanded Usage of Superplastic Forming of Aluminium Sheet for Automotive Applications Series Production of Automotive Body Panels in 5083-SPF using a new Press Concept Progress Towards High Superplastic Strain Rate Aluminium Alloys Superplastic Behavior of a Fine Grained AZ61 Alloy Processed by Large Strain Hot Rolling High Temperature Deformation Behaviour of a Mg-0.8Al Alloy Lowering the Heat - The Development of Reduced SPF Temperature Titanium Alloys for Aircraft Production Applying Superplastic Forming Principles to Titanium Sheet Metal Forming Problems The Superplastic Forming Technology of Ti-6Al-4V Titanium Alloy Bellows Filaments in Superplastic Deformed SiC Particle Reinforced Aluminium Alloy Matrix Composites Problems Encountered in Superplastic Forming of Al 5083 Parts Superplastic Blow Forming of 2219 Aluminium Alloy High Temperature Ductility and Deformation Mechanism in a 2024 Aluminium Alloy Application Studies of New Process and Material for Low-Cost SPF/DB Panel Forming Technology Superplasticity in Commercial Al 7475 High-Strain-Rate Superplasticity in Oxide Ceramics Dopant Effect on the High-Temperature Grain Boundary Sliding in Alumina Superplastic Phenomenon and Electric Properties of Sc2O3 Doped Zirconia-Based Ceramics Application of Pseudo-Superplasticity to Produce TiN/Ti5Si3 and TiC/Ti5Si3 Nano Grain Composites for Micro Molding Production of -TiAl Sheets with Improved Superplastic Properties by Pack Rolling Role of Diffusion Creep in a Superplastic Zirconia-Alumina Composite High-Strain-Rate Superplasticity in 3mol%-Y2O3-Stabilized Tetragonal ZrO2 Dispersed with 30vol% MgAl2O4 Spinel Small Dopant Effect on the Superplastic Flow and Failure in 3Y-TZP Effect of Spinel Second Phase on High Temperature Deformation in Alumina Creep of Zirconia/Nickel Composites Plastic Behaviour of Nanostructured Yttria Tetragonal Zirconia Polycrystals: The Effect of Yttrium Segregation Effect of Yttrium on the Deformation of Nanocrystalline ZrO2 at Elevated Temperatures Superplastic Behavior in Small Amount of Ge-Ti Co-Doped TZP Deformation Processing, Recrystallization and Grain Boundaries in Superplastic Aluminum Alloys In Situ Observations of Microstructural Evolution During Deformation of Supral 100 Obituary, Professor Harvey M Flower FIM FRAeS The Influence of Al3Zr Precipitation on the Superplastic Behaviour of Aluminium Alloys Recrystallized Grain Size in Cold-Rolled and Annealed AZ31 Wrought Magnesium Alloys Affected by Rolling Direction Producing Superplastic Ultrafine-Grained Aluminum Alloys through Severe Plastic Deformation Microstructural Aspects in Superplasticity of Ultrafine-Grained SPD Alloys Superplastic Behaviour and Microstructure Evolution in a Commercial Ultra-Fine Grained Al-Mg-Sc Alloy Ultrafine-Grain Structures Produced by Severe Deformation Processing Fine Microstructure Production Through Sandglass Extrusion Effect of Grain Size and Microstructure on Appearance of Low Temperature Superplasticity in Al-Mg Alloy Characterization of Submicron-Grained Ti-6Al-4V Sheets with Enhanced Superplastic Properties Achieving Superplasticity in the 7055 Aluminum Alloy Superplasticity in an 7475 Aluminum Alloy Subjected to Equal Channel Angular Extrusion Development of Submicrocrystalline Titanium Alloys Using "abc" Isothermal Forging Achievement of Low Temperature Superplasticity in a Commercial Aluminium Alloy Processed by Equal-Channel Angular Extrusion High Temperature Deformation and Crystallographic Orientation Distribution for an Al-Mg-Mn Alloy Sheet Worked by Continuous Cyclic Bending Influence of Channel Geometry on Superplasticity in Equal-Channel Angular Pressing Superplasticity of a Cu-Zn-Sn Alloy Processed by Equal-Channel Angular Pressing Microstructure and Superplastic Properties at Room Temperature in Zn-22Al Alloy after Equal-Channel-Angular Extrusion A Nano-Crystalline Zn-Al Alloy with High Speed Superplasticity at Room Temperature and the Application for Seismic Damper Superplastic Forming of 7475 Al Sheet after Friction Stir Processing (FSP) The Dieless Drawing of High Carbon Steel Sandwich Panel with Aluminium Foam Core through Superplastic Diffusion Bonding Diffusion Bonding on Superplastic-Aluminium and -Magnesium Alloys Use of Laser(s) in the Process of Superplastic Forming and Diffusion Bonding Enhanced Foaming of Cellular Metals by Internal Stress Superplasticity