scholarly journals Microstructural processes occurring during creep of friction stir welded AA2024-T3 alloy

2020 ◽  
Vol 65 (2) ◽  
pp. 53-64
Author(s):  
Michael Regev ◽  
Stefano Spigarelli
Keyword(s):  
Electron Microscopy ◽  
Aluminum Alloy ◽  
Creep Behavior ◽  
Welding Process ◽  
Parent Material ◽  
Fusion Welding ◽  
Creep Tests ◽  
Butt Weld ◽  
Friction Stir ◽  
Secondary Precipitation

The poor weldability of AA2024 aluminum alloy limits its use for industrial applications. Being a non-fusion welding process, Friction Stir Welding (FSW) seems to be a promising solution for welding this alloy. FSW was applied in the current study in order to butt weld AA2024-T3 aluminum alloy plates and to study the creep behavior of the weld. Creep tests were conducted at 250 0C and 315 0C both on the parent material and on the friction stir welded specimens. A comprehensive Transmission Electron Microscopy (TEM) study together with High Resolution Scanning Electron Microscopy (HRSEM) study and Energy Dispersive X-ray Spectroscopy (EDS) analysis were conducted in order to investigate the microstructural processes. The parent material seems to contain two kinds of Curich precipitates - coarse precipitates having the size of a few microns each and uniformly dispersed fine nanosized precipitates. However, this microstructure was found to be unstable at the temperature range of 250-315 0C, secondary precipitation was found to take place, this secondary precipitation is responsible for grain boundary decoration and the appearance of secondary rod-shaped precipitates and for some degree of coarsening of the nanosized precipitates inside the grains. TEM study yielded that the material undergoes dynamic recrystallization (DRX) during creep as well as during the FSW process. Various stages of the development of dislocation networks into a cellular dislocation structure and finally into dislocation free recrystallized grains were recorded. The friction stir welded material, which has already recrystallized during welding, undergoes DRX during creep so that ultra-fine grains are being created concurrently. Precipitation processes at the friction stir welded material occur as well during creep. The instability of the microstructure during creep and exposure to high temperature plays an important role in the analysis of the creep results. The influence of the above microstructure changes occurring during creep on the creep behavior will be referred and discussed.

Tensile Properties and Microstructure of Friction Stir Welded Joints 2195-T8 Aluminum Alloy

2016 ◽  
Vol 835 ◽  
pp. 191-196 ◽  
Author(s):  
Kookil No ◽  
Ye Rim Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo ◽  
Ho Sung Lee
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Welding Process ◽  
Tensile Tests ◽  
Fusion Welding ◽  
Homogeneous Microstructure ◽  
Rotating Speed ◽  
Friction Stir ◽  
Reactive Property

Friction stir welding is a widely used welding process for aluminum alloys because it avoids many of the problems of conventional fusion welding. This process is beneficial especially for lithium containing aluminum alloys in which the reactive property of element Li causes porosity and hot cracking during melting and solidification. In friction stir welding process, each region undergoes different thermo-mechanical cycles and produces a non-homogeneous microstructure. In the present study, the mechanical properties and microstructure of a 2195-T8 aluminum alloy joined with friction stir welding were investigated. The change in microstructure across the welded joint was found to correspond to microhardness measurement. The microstructure was characterized by the presence of severely deformed grains and fine recrystallized grains depending on the region. Tensile tests shows the optimum condition was obtained at the tool rotating speed of 600rpm and the traveling speed range from 180 to 300mm/min.

EFFECT OF PRE-HEATING ON THE MECHANICAL PROPERTIES OF FRICTION STIR WELDING FOR 6061 ALUMINUM ALLOY

2021 ◽  
Vol 25 (Special) ◽  
pp. 2-124-2-134
Author(s):  
Omer T. Abbas ◽  
◽  
Abbas A. Ayoub ◽  
Fouad A. Saleh ◽  
◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Welding Process ◽  
Fusion Welding ◽  
Friction Stir ◽  
Aluminum Alloy 6061 ◽  
Wide Range ◽  
Wrought Aluminum ◽  
Solid State Joining ◽  
Alloy 6061

Friction stir welding (FSW) process is a solid-state joining invented via the Welding Institute in 1991 at a great rate emerging as an application by fusion welding for joining different alloys. The wrought aluminum alloy 6061 is heat treatable and possesses a high corrosion resistance. This alloy has been used in a wide range of applications, like arenas gymnasiums and trains bodies. Aluminum alloy 6061 cannot be easily welded by the conventional fusion welding process because of the cracks that make the mechanical of welding joint very weak. In FSW, many parameters effect on its welding process. In the present research, the pre-heating effect on the aluminum 6061 sheet at 100°C and 150°C was studied. This heat has to be given for obtaining a defect-free as well as quality joint. Result manifested that the welding without pre-heating the parent metal at a (1120 r.p.m) rotational speed and a (30 mm/min) welding speed gave the best result of the ultimate tensile strength (236 N/mm2).

Novel Technique for Joining of Thick Section Difficult-to-Weld Aluminium Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 1125-1130 ◽  
Author(s):  
R. Ilyushenko ◽  
V. Nesterenkov
Keyword(s):  
Aluminium Alloys ◽  
Electron Beam Welding ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Parent Material ◽  
Al Alloys ◽  
Fusion Welding ◽  
Grain Structure ◽  
Liquation Cracking ◽  
Friction Stir

One of the “show stoppers” in fusion welding of highly alloyed aerospace aluminium alloys is their susceptibility for liquation cracking in the weld heat-affected zone. Liquation cracking is a microscopic intergranular discontinuity, which occurs under the effect of welding thermal cycle and in the presence of stresses involved with the welding process. These intergranular discontinuities are often observed in welding of thick plates and extrusions, which usually have relatively coarse elongated grains, that are generally oriented parallel to each other. Friction Stir Welding (FSW) is a low temperature non- fusion process, which produces very fine equiaxed grain structure in the weld nugget for majority of Al-alloys. It was found that bead-onplate FS welds performed on alloy, which in fusion welding is susceptible to liquation cracking, were crack free. It was therefore proposed to use FSW for grain refining of the parent material by putting a number of overlapping FS welds onto the edges of both parent plates prior to joining by fusion welding. Experimentation has shown that there was no liquation cracking after the final weld was performed. This novel welding method has been successfully proven for Electron Beam Welding (EBW) of various Al-alloys including joining of dissimilar materials. The details of experiments as well as welded coupons test results are presented.

scholarly journals Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

2017 ◽  
Vol 37 (1) ◽  
pp. 6-21 ◽  
Author(s):  
C. Rajendrana ◽  
K. Srinivasan ◽  
V. Balasubramanian ◽  
H. Balaji ◽  
P. Selvaraj
Keyword(s):  
Tensile Strength ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Weight Ratio ◽  
Welding Process ◽  
Lap Joints ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Friction Stir

AbstractAA2014 aluminum alloy (Al-Cu alloy) has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW) parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE), analysis of variance (ANOVA), response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

Microstructure Stability During Creep of Friction Stir Welded AZ31B Magnesium Alloy

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Michael Regev ◽  
Stefano Spigarelli ◽  
Marcello Cabibbo
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Parent Material ◽  
The Other ◽  
Creep Tests ◽  
Butt Weld ◽  
Friction Stir ◽  
Microstructure Stability ◽  
Az31b Alloy

Friction stir welding (FSW) was applied in the current study in order to butt weld AZ31B-H24 alloy plates. Creep tests were conducted both on the parent material and on the friction stir welded specimens. The microstructure of the AZ31B alloy was found to be unstable under creep conditions. In the case of friction stir welded AZ31B, the material undergoes during FSW both recrystallization and grain growth, then the exposure to temperature during creep yields an extensive additional grain growth. On the other hand, twinning and twin-induced recrystallization occur as well during creep so that ultrafine grains are being created concurrently.

Observation of the Behavior of Fatigue Cracks in Friction Stir Welded Aluminum Alloy Joints

2008 ◽  
Vol 385-387 ◽  
pp. 797-800 ◽  
Author(s):  
Keiji Katsuki ◽  
Markus Gutensohn ◽  
Masahiro Endo ◽  
Dietmar Eifler
Keyword(s):  
Aluminum Alloy ◽  
Low Cost ◽  
Fatigue Cracks ◽  
Welding Process ◽  
Parent Material ◽  
Stress Axis ◽  
Local Anisotropy ◽  
Artificial Defect ◽  
Friction Stir ◽  
Crack Paths

Friction stir welding (FSW) is a new solid-state welding process that can produce low-cost and high-quality joints of especially aluminum and mgnesium alloys. The welding zone consists of different regions with characteristic microstructuralal details such as a weld nugget, a thermo-mechanically-affected zone (TMAZ) and a heat-affected zone (HAZ). Tension-compression fatigue tests were performed using FSW aluminum alloy AA5454 sheet specimens at a stress ratio of –1. To investigate the propagation behavior of small fatigue cracks in those regions, an artificial defect was introduced into different defined locations in the FSW specimens as well as into the parent material specimens. The crack propagation rates depended on the defined locations and were a function of the hardness; that is, the lower the hardness was, the higher the propagation rate was. The crack paths were mostly perpendicular to the applied stress axis, but some crack paths exhibited deviations by the influence of the local anisotropy of the microstructure.

Dimensional Analysis of Thermal Fields Surrounding Friction Stir Welding Process

2014 ◽  
Author(s):  
Lewis N. Payton ◽  
Vishnu Vardhan Chandrasekaran ◽  
Wesley S. Hunko
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Welding Process ◽  
Temperature Fields ◽  
Analytical Comparison ◽  
Friction Stir ◽  
Thermal Fields ◽  
Designed Experiment ◽  
Pi Theorem ◽  
Alloy 6061

A dimensionless correlation is developed based on Buckingham’s Pi-Theorem to estimate the temperature fields generated by the movement of a tool during the Friction Stir Welding of an aluminum alloy (6061-T6). Symmetrical thermocouple measurements are taken during a statistically designed experiment using different factor levels (RPM, Traverse, etc). Analytical comparison (using multivariate ANOVA) validates the predicted dimensionless correlation including the often-reported difference between the advancing versus retreating side of the Friction Stir Tool.

scholarly journals Increasing of the Mechanical Properties of Friction Stir Welded Joints of 6061 Aluminum Alloy by Introducing Alumina Particles

2017 ◽  
Vol 17 (2) ◽  
pp. 29-40 ◽  
Author(s):  
M. A. Tashkandi ◽  
J. A. Al-Jarrah ◽  
M. Ibrahim
Keyword(s):  
Aluminum Alloy ◽  
Base Metal ◽  
Welded Joints ◽  
Volume Fraction ◽  
Welding Process ◽  
Welding Zone ◽  
6061 Aluminum Alloy ◽  
Friction Stir ◽  
Alumina Particles ◽  
Welding Line

AbstractThe main aim of this investigation is to produce a welding joint of higher strength than that of base metals. Composite welded joints were produced by friction stir welding process. 6061 aluminum alloy was used as a base metal and alumina particles added to welding zone to form metal matrix composites. The volume fraction of alumina particles incorporated in this study were 2, 4, 6, 8 and 10 vol% were added on both sides of welding line. Also, the alumina particles were pre-mixed with magnesium particles prior being added to the welding zone. Magnesium particles were used to enhance the bonding between the alumina particles and the matrix of 6061 aluminum alloy. Friction stir welded joints containing alumina particles were successfully obtained and it was observed that the strength of these joints was better than that of base metal. Experimental results showed that incorporating volume fraction of alumina particles up to 6 vol% into the welding zone led to higher strength of the composite welded joints as compared to plain welded joints.

scholarly journals Investigations on force generation and joint properties of dissimilar thickness friction stir corner welded AA 5086 alloy

2020 ◽  
Vol 40 (1) ◽  
pp. 67-74
Author(s):  
Manigandan Krishnan ◽  
Senthilkumar Subramaniam
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Welding Process ◽  
Spindle Motor ◽  
Parent Material ◽  
Force Generation ◽  
Friction Stir ◽  
Current Consumption ◽  
Spindle Motor Current

The force generation, joint mechanical and metallurgical properties of friction stir corner welded non-heat treatable AA 5086 aluminum alloy are investigated in this paper. The friction stir welding process is carried out with the plate thicknesses of 6 mm and 4 mm. The welding speed, tool rotational speed and tool plunge depth were considered as the process parameters to conduct the welding experiments. The machine spindle motor current consumption and tool down force generation during friction stir welding were analyzed. The microstructures of various joint regions were observed. The tensile samples revealed the tensile strength of 197 MPa with tool rotational and welding speeds of 1,000 rev/min and 150 mm/min respectively, which is 78 % of parent material tensile strength. A maximum micro hardness of 98 HV was observed at thermomechanically joint affected zone, which was welded with tool rotation of 1,000 rev/min and welding speed of 190 mm/min.

scholarly journals The Effect of Copper and Brass on Friction Stir Welded Dissimilar Aluminium Alloy When Used as in Thin Sheet Form

2016 ◽  
Vol 45 (2) ◽  
pp. 118-122
Author(s):  
G. Gopala Krishna ◽  
P.Ram Reddy ◽  
M.Manzoor Hussain
Keyword(s):  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Low Cost ◽  
Thin Sheet ◽  
Welding Process ◽  
Cost Effective ◽  
Tensile Tests ◽  
Fusion Welding ◽  
Friction Stir ◽  
Effect Of Copper

In recent year’s aluminium and aluminium alloys are most widely used in many applications because of light weight, good formability and malleability, corrosion resistance, moderate strength and low cost. Friction Stir Welding (FSW) process is efficient and cost effective method for welding aluminium and aluminium alloys. FSW is a solid state welding process that means the material is not melted during the process. Complete welding process accomplishes below the melting point of materials so it overcomes many welding defects that usually happens with conventional fusion welding technique which were initially used for low melting materials. Though this process is initially developed for low melting materials but now process is widely used for a variety of other materials including titanium, steel and also for composites. The present butt jointed FSW experimental work has been done in two ways. Initially a comparison of tensile properties of friction stir (FS) welded similar aluminium alloy (AA6351 with AA6351) and dissimilar aluminium alloy (AA6351 with AA5083) combinations. Later the effect of impurities (copper and brass) in sheet form (0.1 mm thick) when used as insert in between two dissimilar aluminium alloy (AA6351 with AA5083) plates during FSW. Tensile tests were performed for these combinations and results were compared for with and without using strip material (copper and brass).

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