scholarly journals Shoulderless Friction Stir Welding: a low-force solid state keyhole joining technique for deep welding of labile structures

2021 ◽  
Author(s):  
Max Hossfeld
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Contact Area ◽  
Industrial Application ◽  
Heat Input ◽  
Friction Stir ◽  
Joining Technology ◽  
Low Distortion ◽  
Opening Up ◽  
Limited Process

AbstractThis paper reports on the possibility of performing Friction Stir Welding (FSW) without the usual immanent shoulder to enable FS processing to deep welding of narrow and labile structures and applications where backing is not possible. Requirements and prerequisites, advantages and limitations for Shoulderless Friction Stir Welding (SLFSW) are discussed and an industrial application of the joining technology is presented. For leaving the shoulder out, its central functions in FSW have to be transferred to the pin. The resulting tool design of SLFSW is comparably small and slim and so reduces contact area and effective lever and in turn forces and heat input during processing. SLFSW allows welding paths almost at the edge of components and enables a complete and gap-free joining while a deformation of overhanging structures can be avoided. Compared to standard FSW processes, force reductions of about 80–85 % and power reductions of about 75–80 % were found in this study for a 6.5 mm deep weld opening up additional potential for integration with other spindle processes like milling. The locally very limited process impact of SLFSW resulted in comparably low distortion with a part precision reached of +/− 0.05 mm.

scholarly journals A Cooler Weld

2003 ◽  
Vol 125 (03) ◽  
pp. D10-D16 ◽  
Author(s):  
Matt Hansen
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Arc Welding ◽  
Federal Aviation Administration ◽  
Phase Changes ◽  
Fusion Welding ◽  
Friction Stir ◽  
State Process ◽  
Joining Technology ◽  
The Us

This article provides details of a low-temperature joining technology called friction stir welding. Friction stir welding (FSW) uses a cylindrical, shouldered tool with a profiled pin that is rotated and slowly plunged into the joint line between two pieces of sheet or plate material. According to an engineer, stir welding eliminated 60 percent of the rivets that the plane would have otherwise required. Eclipse Aviation Corp., Albuquerque, NM, is building a separate plant to house its stir welding operations for commercial production, once its plane receives certification by the US Federal Aviation Administration. FSW is a solid-state process, more like forging and extruding than to fusion welding. Since the process is solid state, the joint is not subject to any shrinkage because of phase changes. The process also introduces minimal heat into the weld, so the heat-affected zone is relatively small in comparison to arc welding.

Features of structure formation processes in AA2024 alloy joints formed by the friction stir welding with bobbin tool

2021 ◽  
Vol 23 (2) ◽  
pp. 98-115
Author(s):  
Alexey Ivanov ◽  
◽  
Valery Rubtsov ◽  
Andrey Chumaevskii ◽  
Kseniya Osipovich ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Structure Formation ◽  
Welded Joints ◽  
Heat Input ◽  
Welded Joint ◽  
Welding Process ◽  
Tool Material ◽  
Travel Speed ◽  
Material System ◽  
Friction Stir

Introduction. One of friction stir welding types is the bobbin friction stir welding (BFSW) process, which allows to obtain welded joints in various configurations without using a substrate and axial embedding force, as well as to reduce heat loss and temperature gradient across the welded material thickness. This makes the BFSW process effective for welding aluminum alloys, which properties are determined by their structural-phase state. According to research data, the temperature and strain rate of the welded material have some value intervals in which strong defect-free joints are formed. At the same time, much less attention has been paid to the mechanisms of structure formation in the BFSW process. Therefore, to solve the problem of obtaining defect-free and strong welded joints by BFSW, an extended understanding of the basic mechanisms of structure formation in the welding process is required. The aim of this work is to research the mechanisms of structure formation in welded joint of AA2024 alloy obtained by bobbin tool friction stir welding with variation of the welding speed. Results and discussion. Weld formation conditions during BFSW process are determined by heat input into a welded material, its fragmentation and plastic flow around the welding tool, which depend on the ratio of tool rotation speed and tool travel speed. Mechanisms of joint formation are based on a combination of equally important processes of adhesive interaction in “tool-material” system and extrusion of metal into the region behind the welding tool. Combined with heat dissipation conditions and the configuration of the “tool-material” system, this leads to material extrusion from a welded joint and its decompaction. This results in formation of extended defects. Increasing in tool travel speed reduce the specific heat input, but in case of extended joints welding an amount of heat released in joint increases because of specific heat removal conditions. As a result, the conditions of adhesion interaction and extrusion processes change, which leads either to the growth of existing defects or to the formation of new ones. Taking into account the complexity of mechanisms of structure formation in joint obtained by BFSW, an obtaining of defect-free joints implies a necessary usage of various nondestructive testing methods in combination with an adaptive control of technological parameters directly in course of a welding process.

On the solid-state-bonding mechanism in friction stir welding

2020 ◽  
Vol 37 ◽  
pp. 100727
Author(s):  
Xue Wang ◽  
Yanfei Gao ◽  
Martin McDonnell ◽  
Zhili Feng
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Bonding Mechanism ◽  
Friction Stir ◽  
Solid State Bonding

Characterization o Solid-State Vortices Associated with the Friction-Stir Welding of Copper to Aluminum

1998 ◽  
Vol 4 (S2) ◽  
pp. 530-531
Author(s):  
R. D. Flores ◽  
L. E. Murr ◽  
E. A. Trillo
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Solid State ◽  
Weld Zone ◽  
Thick Plates ◽  
6061 Aluminum Alloy ◽  
Friction Stir ◽  
The Past ◽  
Joining Process

Although friction-stir welding has been developing as a viable industrial joining process over the past decade, only little attention has been given to the elucidation of associated microstructures. We have recently produced welds of copper to 6061 aluminum alloy using the technique illustrated in Fig. 1. In this process, a steel tool rod (0.6 cm diameter) or head-pin (HP) traverses the seam of 0.64 cm thick plates of copper butted against 6061-T6 aluminum at a rate (T in Fig. 1) of 1 mm/s; and rotating at a speed (R in Fig. 1) of 650 rpm (Fig. 1). A rather remarkable welding of these two materials results at temperatures measured to be around 400°C for 6061-T6 aluminum welded to itself. Consequently, the metals are stirred into one another by extreme plastic deformation which universally seems to involve dynamic recrystallization in the actual weld zone. There is no melting.

Probeless Tool Aided Friction Stir Welding as a Fabrication Technique for Tungsten Embedded Mechanical Composite of Copper

2014 ◽  
Author(s):  
Yogita Ahuja ◽  
Raafat Ibrahim ◽  
Anna Paradowska ◽  
Daniel Riley
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Base Metal ◽  
Parametric Study ◽  
Effective Parameter ◽  
Frictional Heat ◽  
Fabrication Technique ◽  
Shear Testing ◽  
Friction Stir ◽  
Parameter Combination

Friction stir welding (FSW) is a relatively new solid state metallurgical joining technique. It flourishes on the simple principle of utilising frictional heat by the stirring motion of a non-consumable rotating tool to create the seam. Feasibility of FSW aided by a newly designed probeless tool was investigated for fabricating copper-tungsten mechanical composite. The most effective parameter combination was determined by conducting a parametric study of the probeless tool aided FSW copper. Strength of the mechanical composite fabricated at this condition was evaluated through punch shear testing. Punch shear testing established that the friction stir welded interface of the copper-tungsten composite was 87% as strong as the base metal (i.e. copper). Advantages of the designed technique have been summarised.

scholarly journals Material Flow Visualization of Dissimilar Friction STIR Welding Process Using Nano-Computed Tomography

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Xun Liu ◽  
Sheng Zhao ◽  
Kai Chen ◽  
Jun Ni
Keyword(s):  
Computed Tomography ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Volume Fraction ◽  
Weld Zone ◽  
Process Conditions ◽  
Rotating Speed ◽  
Friction Stir ◽  
Small Tool

In this study, the friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel is analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-computed tomography (nano-CT) is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset, and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.

Axial Force Reduction in Friction Stir Welding of AA6061-T6 at Right Angle

2014 ◽  
Author(s):  
Yousef Imani ◽  
Michel Guillot
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Axial Force ◽  
Tool Design ◽  
Industrial Robots ◽  
Welding Parameters ◽  
Minor Effect ◽  
Friction Stir ◽  
Force Reduction ◽  
Solid State Joining

Invented in 1991, friction stir welding (FSW) is a new solid state joining technique. This process has many advantages over fusion welding techniques including absence of filler material, shielding gas, fumes and intensive light, solid state joining, better microstructure, better strength and fatigue life, and etc. The difficulty with FSW is in the high forces involved especially in axial direction which requires use of robust fixturing and very stiff FSW machines. Reduction of FSW force would simplify implementation of the process on less stiff CNC machines and industrial robots. In this paper axial welding force reduction is investigated by use of tool design and welding parameters in FSW of 3.07 mm thick AA6061-T6 sheets at right angle. Attempt is made to reduce the required axial force while having acceptable ultimate tensile strength (UTS). It is found that shoulder working diameter and shoulder angle are the most important parameters in the axial force determination yet pin angle has minor effect. According to the developed artificial neural network (ANN) model, proper selection of shoulder diameter and angle can lead to approximately 40% force reduction with acceptable UTS. Regions of tool design and welding parameters are found which result in reduced axial force along with acceptable UTS.

Sign in / Sign up

Export Citation Format

Share Document