Residual strains and microstructure development in single and sequential double sided friction stir welds in RQT-701 steel

2008 ◽  
Vol 492 (1-2) ◽  
pp. 35-44 ◽  
Author(s):  
S.J. Barnes ◽  
A. Steuwer ◽  
S. Mahawish ◽  
R. Johnson ◽  
P.J. Withers
Keyword(s):  
Microstructure Development ◽  
Friction Stir ◽  
Residual Strains

Microstructure Development in Copper Welded by the FSW-Process

2003 ◽  
Vol 807 ◽  
Author(s):  
Therese Källgren ◽  
Rolf Sandström
Keyword(s):  
Welding Process ◽  
Mechanical Deformation ◽  
Microstructure Development ◽  
Friction Stir ◽  
Friction Heat ◽  
The Third ◽  
Lower Temperature ◽  
Weld Root ◽  
Nuclear Fuel Waste ◽  
Joining Process

ABSTRACTTo ensure safe storage of nuclear fuel waste, copper canisters are proposed as corrosion barrier. One alternative for sealing the copper canisters is Friction Stir Welding (FSW). During the joining process friction heat and mechanical deformation appear between the rotating tool and the material being welded. Liquid metal will not form, since this is a solid state welding process. Three distinct microstructural zones are developed namely the nugget, the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ). The nugget is in the centre of the weld, where the pin is located and where severe plastic deformation occurs that leads to recrystallisation. Surrounding the nugget, the TMAZ is only partially recrystallised, due to lower temperature increase and deformation compared to the nugget. The third zone, HAZ, surrounds the TMAZ. The initial nugget can have a classic round aluminium nugget image, when the welding conditions are cold, but the steady state nugget, is wider near the shoulder and shorter in the weld root.

scholarly journals Microstructure Development in Additive Friction Stir-Deposited Cu

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1538
Author(s):  
Jonathan L. Priedeman ◽  
Brandon J. Phillips ◽  
Jessica J. Lopez ◽  
Brett E. Tucker Roper ◽  
B. Chad Hornbuckle ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Vickers Hardness ◽  
Work Hardening ◽  
Surface Oxide ◽  
Microstructure Development ◽  
Friction Stir ◽  
Grain Sizes

This work details the additive friction stir-deposition (AFS-D) of copper and evaluation of its microstructure evolution and hardness. During deposition, a surface oxide is formed on the deposit exterior. A very fine porosity is formed at the substrate–deposit interface. The deposit (four layers of 1 mm nominal height) is otherwise fully dense. The grains appear to have recrystallized throughout the deposit with varying levels of refinement. The prevalence of twinning was found to be dependent upon the grain size, with larger local grain sizes having a higher number of twins. Vickers hardness measurements reveal that the deposit is softer than the starting feedstock. This result indicates that grain refinement and/or higher twin densities do not replace work hardening contributions to strengthen Cu processed by additive friction stir-deposition.

scholarly journals Neutron diffraction strain mapping in engineering materials

2014 ◽  
Vol 70 (a1) ◽  
pp. C732-C732
Author(s):  
Edward Payzant ◽  
Lindsay Sochalski-Kolbus
Keyword(s):  
Neutron Diffraction ◽  
Strain Mapping ◽  
Friction Stir ◽  
Lattice Strains ◽  
High Penetration ◽  
Residual Strains ◽  
Engineering Materials ◽  
And Performance ◽  
Non Destructive ◽  
Ods Alloy

Bragg peak positions with precisions of a few parts in 10^4 are typically necessary to provide the strain resolution required for measurement of the residual strains in bulk materials. Neutron diffraction, mainly because of its high penetration in many engineering materials, provides a unique non-destructive capability for strain measurement. Dedicated instruments for mapping lattice strains using neutron diffraction, a technique first demonstrated in the 1980s, are found at all major neutron scattering facilities around the world. Residual stresses typically arise during synthesis, forming, joining, thermal processing, or use of engineering materials and can significantly impact the strength and performance of the final part. We present two recent examples of strain-mapping experiments conducted at the HB-2B beamline at the High Flux Isotope Reactor. Strain-mapping data collected on a friction stir welded ODS alloy reveals changes in texture and stress resulting from the FSW process, and dependent on the FSW process variables. Mapping experiments on steel conduit intended for the ITER project show the strain distribution from the forming operations, and the partial reduction of these strains through high temperature annealing.

Synchrotron Energy-Dispersive X-Ray Diffraction Analysis of Residual Strains around Friction Welds between Dissimilar Aluminium and Nickel Alloys

2008 ◽  
Vol 571-572 ◽  
pp. 407-412 ◽  
Author(s):  
Tea Sung Jun ◽  
Shu Yan Zhang ◽  
Mina Golshan ◽  
Matthew J. Peel ◽  
David G. Richards ◽  
...  
Keyword(s):  
Friction Welding ◽  
Nickel Alloys ◽  
Dissimilar Materials ◽  
High Energy ◽  
Bond Line ◽  
Energy Dispersive ◽  
Mapping Technique ◽  
Friction Stir ◽  
Residual Strains ◽  
Welding Processes

Friction welding processes, such as friction stir welding (FSW) and inertia friction welding (IFW) are popular candidate procedures for joining engineering materials (including dissimilar pairs) for advanced applications. The advantages of friction welding include lack of large scale material melting, ability to join dissimilar materials, and relatively low propensity to introduce defects into the weld joint. For these reasons FSW and IFW have become the subjects of a number of studies aimed at optimising the joining operations to obtain improved joint strength and reduce distortion and residual stress. In the present study we used the diffraction of high energy polychromatic synchrotron X-rays to measure interplanar lattice spacings and deduce nominal elastic strains in friction stir welds between dissimilar aluminium alloys AA5083 and AA6082, and in coupons from inertia friction welds between dissimilar nickel-base superalloys IN718 and RR1000. Energy-dispersive diffraction profiles were collected by two detectors mounted in the horizontal and vertical diffraction planes, providing information about lattice strains in two nearly perpendicular directions lying almost in the plane of the plate samples mounted perpendicularly to the incident beam. Two-dimensional maps of residual stresses in friction-welded joints were constructed. Apart from the 2D mapping technique, the sin2ψ method (transmission) was also used in the case of inertia friction-welded joint between nickel alloys. Comparison between the two results allowed the variation of the lattice parameter with the distance from the bond line to be deduced. It was found that friction welding of two dissimilar materials with significant strength mismatch may lead to the creation of a region of compressive stress in the vicinity of the bond line, in contrast with the behaviour observed for joints between similar materials.

Friction Stir Welding Process Parameter Effects on Workpiece Warpage due to Residual Strains

2011 ◽  
Author(s):  
John G. Michopoulos ◽  
Samuel Lambrakos ◽  
Athanasios Iliopoulos
Keyword(s):  
Friction Stir Welding ◽  
Permanent Deformation ◽  
Welding Process ◽  
Processing Parameters ◽  
Performance Measure ◽  
Element Analysis ◽  
Friction Stir ◽  
Thermally Activated ◽  
Residual Strains ◽  
Welding Processes

An important performance measure of the quality of a weld is the permanent deformation developed during welding processes due to the thermally activated residual strains. This paper presents the results of a sensitivity analysis that determines the effects of processing parameters — such as the speed of rotation and the traveling speed of a rotating friction stir welding (FSW) tool — on the resulting residual strain fields. The problem has been modeled as a thermostructurally coupled problem via Finite Element Analysis of an elastoplastic workpiece under the influence of heat generated from the stirring process and taking into account the temperature dependent yield strength of the material. Results are presented and discussed in the context of our future plans.

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