Effect of Strain Hardening on the Joint Efficiency of an Al-Mg-Sc-Zr Alloy Subjected to Friction Stir Welding

The microstructure and mechanical properties of friction stir welded Al-5.4Mg-0.2Sc-0.1Zr alloy were studied. Defect-free welds were produced in hot extruded, hot rolled and cold rolled initial conditions. Friction stir welding led to the formation of ultrafine-grained structure in stir zone that contributes to overall strengthening. Coherent Al3(Sc,Zr) dispersoids retain partially during welding process that provides a joint efficiency close to 100% in the hot extruded and hot rolled materials. In the cold-rolled state the joint efficiency was found to be only 64%. The relatively low weld strength of the cold rolled material was attributed to the elimination of strain hardening due to the formation of recrystallized structure. It was shown that full strength weld can be achieved in semi-finished products of Al-Mg-Sc alloys in cold-worked and stabilized states being equal to H323 and H341 tempering by friction stir welding.

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Friction-Stir Welding of a Wrought Al-Si-Mg Alloy in As-Fabricated and Heat-Treatment States

Materials ◽

10.3390/ma13040861 ◽

2020 ◽

Vol 13 (4) ◽

pp. 861

Author(s):

Chunxia Wang ◽

Hongbo Cui ◽

Xin Tang ◽

Kezhun He

Keyword(s):

Heat Treatment ◽

Friction Stir Welding ◽

Solution Treatment ◽

Base Material ◽

Welding Process ◽

Age Hardening ◽

Weld Strength ◽

Friction Stir ◽

Joint Efficiency ◽

Al Matrix

A wrought Al-11.3Si-0.6Mg alloy under hot extrusion (T1), solution treatment (T4), and solution treatment + artificial aging (T6) states were friction stir welded at welding speed of 100 mm/min and rotation rate of 800 rpm. The effect of prior heat-treatment on the microstructure and mechanical properties of the welds were investigated. The results show that the microstructures of the nugget zones have little dependence on the initial states of the base material. In the nugget zones, complete recrystallized structures with equaxied grains in the Al matrix were formed under all conditions. The Si particles in the nugget zones are almost unchanged compared with those of their base materials (BMs) in the three states. In contrast, the joint efficiency of the obtained welds was very sensitive to the initial material condition. The joint efficiency under the T1 state is more than 90% due to the fact that the microstructure is almost unchanged, except for the slight coarsening of the Al matrix grains and some of the Mg2Si phases during the friction stir welding process. However, the joint efficiency in the T4 and T6 conditions is only 77.22% and 62.03%, respectively. The relatively low weld strength in the T4 and T6 conditions is due to the elimination of the solid solution strengthening and age hardening effects during friction stir welding. The hardness distributions along the cross section of joints are all W-shaped under T1, T4, and T6 conditions.

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Friction Stir Welding of an Al-Mg-Sc-Zr Alloy with Ultra-Fined Grained Structure

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.365 ◽

2014 ◽

Vol 794-796 ◽

pp. 365-370

Author(s):

Sergey Malopheyev ◽

Sergey Mironov ◽

Vladislav Kulitskiy ◽

Rustam Kaibyshev

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Weld Zone ◽

Friction Stir ◽

Angular Pressing ◽

Joint Efficiency ◽

Cold Rolled ◽

Rolled Condition ◽

Hot Rolled ◽

Zr Alloy

Effect of friction stir welding (FSW) on mechanical properties and microstructure of Al-5.4Mg-0.2Sc-0.1Zr sheets with ultra-fined grained (UFG) structure was studied. The UFG-sheets were produced by equal-channel angular pressing (ECAP) followed either by cold or hot rolling. FSW was found to be very effective for retaining the UFG microstructure as well as constituent coherent nano-scale dispersoids in the welded material. Despite the preservation effect, however, the essential material softening was observed in the weld zone. This was attributed to the recrystallization occurring during FSW. The joint efficiency for yield strength of the obtained friction stir welds was found to be 81% in the hot rolled condition and only 55% in the cold rolled state. The relatively low joint efficiency was associated with the recrystallization softening as well as with the formation of a specific “kissing bond” defect in the stir zone. The joint efficiency is believed may be improved by adjusting of welding conditions and/or tool design.

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Friction-Stir Welding of Zr-Modified AA5083 Sheets in Different Conditions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.877.365 ◽

2016 ◽

Vol 877 ◽

pp. 365-370

Author(s):

Sergey Malopheyev ◽

Sergey Mironov ◽

Rustam Kaibyshev

Keyword(s):

Friction Stir Welding ◽

Post Weld Heat Treatment ◽

Stir Zone ◽

Friction Stir ◽

Ultrafine Grained ◽

Aa5083 Aluminum Alloy ◽

Cold Rolled ◽

Material Conditions ◽

Hot Rolled ◽

Zone Microstructure

The effect of friction-stir welding (FSW) on microstructure and mechanical properties of Zr-modified AA5083 aluminum alloy was studied. FSW was observed to lead to the formation of fully recrystallized ultrafine-grained microstructures and preservation of nanoscale dispersoids in stir zone. The joint efficiency of the friction-stir welds for ultimate tensile strength was found to be 94% and 74% in the hot-rolled and cold-rolled preprocessed material conditions. The stir zone microstructure was predicted to be stable against abnormal grain growth during post-weld heat treatment.

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Investigation on the Effects of Process Parameters on Defect Formation in Friction Stir Welded Samples via Predictive Numerical Modeling and Experiments

Volume 1: Processes ◽

10.1115/msec2017-3092 ◽

2017 ◽

Author(s):

Abhishek Ajri ◽

Yung C. Shin

Keyword(s):

Friction Stir Welding ◽

Process Parameters ◽

Defect Formation ◽

Welding Process ◽

Weld Strength ◽

Friction Stir Weld ◽

Optimum Process ◽

Friction Stir ◽

Different Types ◽

Induced Flow

Setting optimum process parameters is very critical in achieving a sound friction stir weld joint. Understanding the formation of defects and developing techniques to minimize them can help in improving the overall weld strength. The most common defects in friction stir welding are tunnel defects, cavities and excess flash formation which are caused due to incorrect tool rotational or advancing speed. In this paper, the formation of these defects is explained with the help of an experimentally verified 3D finite element model. It was observed that the asymmetricity in temperature distribution varies for different types of defects formed during friction stir welding. The location of the defect also changes based on the shoulder induced flow and pin induced flow during friction stir welding. Besides formation of defects like excess flash, cavity defects, tunnel/wormhole defects, two types of groove like defects are also discussed in this paper. By studying the different types of defects formed, a methodology is proposed to recognize these defects and counter them by modifying the process parameters to achieve a sound joint for a displacement based friction stir welding process.

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A combined wavelet packet and Hilbert-Huang transform for defect detection and modelling of weld strength in friction stir welding process

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2016.04.002 ◽

2016 ◽

Vol 22 ◽

pp. 260-268 ◽

Cited By ~ 19

Author(s):

Bipul Das ◽

Sukhomay Pal ◽

Swarup Bag

Keyword(s):

Friction Stir Welding ◽

Defect Detection ◽

Wavelet Packet ◽

Welding Process ◽

Weld Strength ◽

Hilbert Huang Transform ◽

Friction Stir ◽

Friction Stir Welding Process

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Experimental Study of the Temperature Distribution and Microstructure of Plunge Stage in Friction Stir Welding Process by the Tool with Triangle Pin

Archive of Mechanical Engineering ◽

10.2478/meceng-2014-0028 ◽

2014 ◽

Vol 61 (3) ◽

pp. 483-493

Author(s):

Hossain Bisadi ◽

Sajad Rasaee ◽

Mohammad Farahmand

Keyword(s):

Friction Stir Welding ◽

Temperature Distribution ◽

Manufacturing Industry ◽

Initial Conditions ◽

Flow Direction ◽

Welding Process ◽

Asymmetric Distribution ◽

Friction Stir ◽

Complete Study

Abstract Considering the developing role of the friction stir welding in manufacturing industry, a complete study on the process is necessary. Studies on each stage of the process in particular, provide a better understanding of friction stir welding, and specially friction stir spot welding. In this study, plunge stage has been studied by experimental methods for investigating the temperature distribution around the tool during the plunge stage and microstructure changes of the workpiece. Experiments were performed on aluminium 7050 plates with coincident measurement of temperature. In the study, the tool which has a triangle pin is used. The results of this study are used as initial conditions for theoretical analysis of welding process. The results show that the temperature distribution around the tool is quite asymmetric. The asymmetric distribution of temperature is due to nonuniform load distribution underneath the tool and tilt angle of it. The temperatures of the points behind the tool are higher compared with points located forward the tool. Microstructural studies showed that four regions with different microstructures are formed around the tool during the process. These areas were separated based on differences in grain size and elongations. Grains near the tool are elongated in a particular direction that show the material flow direction.

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ANALYSIS AND CHARACTERIZATION OF FORMING BEHAVIOR ON DISSIMILAR JOINTS OF AA5052-O TO AA6061-T6 USING UNDERWATER FRICTION STIR WELDING

Surface Review and Letters ◽

10.1142/s0218625x1950121x ◽

2019 ◽

Vol 27 (03) ◽

pp. 1950121

Author(s):

K. TEJONADHA BABU ◽

S. MUTHUKUMARAN ◽

C. SATHIYA NARAYANAN ◽

C. H. BHARAT KUMAR

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Strain Hardening ◽

Welded Joints ◽

Dissimilar Materials ◽

Strain Hardening Exponent ◽

Dissimilar Joints ◽

Friction Stir ◽

Joint Efficiency ◽

Underwater Friction Stir Welding

The effects of underwater friction stir welding (UFSW) on mechanical properties, strain hardening behavior, and formability of dissimilar materials of AA5052-O and AA6061-T6 welded joints were investigated. The mechanical properties of the UFSW joints exhibited higher strength and higher joint efficiency than the conventional friction stir welded joints (CFSW). The maximum joint efficiency of 73% has been attained for UFSW joints, which is due to the effect of welding atmosphere. The hardness of the stir zone (SZ) and heat affected zone (HAZ) are also obtained higher for the UFSW joints. Moreover, the hardening capacity, strain hardening exponent and formability of the UFSW joints were greatly improved over the CFSW joints. The improvement in mechanical properties of the UFSW joints is mainly due to faster cooling rate during welding. The microstructural characteristics revealed the formation of fine grains in the UFSW joints compared to the CFSW joints.

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Optimization of Process Parameters during Friction Stir Welding of Dissimilar Aluminium Alloys (AA 5083 & AA 6061) Using Taguchi L9 Orthogonal Array

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.630 ◽

2014 ◽

Vol 592-594 ◽

pp. 630-635 ◽

Cited By ~ 1

Author(s):

S. Ramesh Babu ◽

P. Karthik ◽

S. Karthik ◽

S. Arun Kumar ◽

Joel Marris

Keyword(s):

Friction Stir Welding ◽

Orthogonal Array ◽

Welding Process ◽

Weld Strength ◽

Welding Parameters ◽

Array Analysis ◽

Friction Stir ◽

Optimum Parameters ◽

Optimization Of Process Parameters ◽

Tool Profiles

In the present study AA5083 and AA6061 were welded using friction stir welding process by controlling the various welding parameters viz. rotational speed, welding speed and Tool axial force for two different tool profiles. Aluminum alloys 5083 and 6061 have similar properties and they both are widely used in marine industries and other transportation industries. In this work the effect of various parameters on the mechanical properties viz. tensile strength and impact strength were studied. In this study the Taguchi approach was used as a design of experiment to set optimum parameters. The experiments were done using Taguchi’s L9 orthogonal array. Analysis of variance test was also performed to obtain the effect of the parameters on the weld strength. Both DOE and ANOVA were performed using MINITAB software.

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