**1. Introduction**

Aluminum materials are being used for variety of purposes like industrial, household, construction, etc., because of its advantages compared with other materials. It is easily available third most abundant material in the earth crust. Pure aluminum materials cannot be used directly for industrial applications due to its poor mechanical and metallurgical properties. With addition of some additives like copper, manganese, magnesium, zinc, silicon, etc., to aluminum materials; aluminum alloys can be produced which possess extraordinary mechanical and metallurgical properties comparison with the pure form of aluminum. Different aluminum alloys which are developed and widely used for various industrial applications are given in **Table 1**. As per the statistics of consumption of materials in industries; steel is occupying first position due to their mechanical properties like hardness, strength, stiffness, etc., In the recent times, the usage of aluminum alloys is growing in many industrial applications instead of steel and steel-based alloys, due to


**Table 1.**

*Various aluminum alloys and its major alloying elements [10].*

its excellent properties such as corrosion resistance [1], light in weight as having one third density of steel, machinability, thermal and electrical conductivity, easy manufacturing methods, low cost of manufacturing, etc. The applications of aluminum alloys are found in variety of applications ranging from basic to complex such as in the making of aircraft bodies [2], construction [3], structural applications [4], transportation, packing, aerospace [5, 6], automobile [4], automotive, railway, personal computers, cutlery, aeronautical and shipbuilding industries [7], naval and marine [8]. All the mentioned applications need to join, two or more parts to create one complete structure or device. Welding is one of the most widely used fabrication technique for joining similar/dissimilar parts permanently. Tungsten inert gas (TIG) and metal inert gas (MIG) welding are generally used joining methods for different materials. But, in case of welding of aluminum alloys by TIG and MIG welding processes, produces welding defects on welded joint like porosity, lack of fusion, incomplete penetration and create many cracks such as hot crack, stress corrosion [9]. Defects in the welded joints weaken the quality characteristics. Welding of aluminum alloys by TIG and MIG welding techniques are not recommended and not economical as well.

Friction stir welding (FSW) is an innovative welding methodology developed to join especially aluminum alloys [4] and other light-weight materials, economically [11] without any severe distortions which expected to influence mechanical and metallurgical behavior of welded sample [6, 12]. The weldability of various aluminum alloys by fusion welding methods like TIG and MIG welding, and FSW are shown in **Figure 1**.

In FSW, the job that is being welded does not melt and recast [12]. Cavaliere et al. [13] had stated that FSW is novel fabrication approach which capable to replace other joining techniques like fastener, riveted and arc welding for production of large-scale applications. FSW has various advantages over other traditional welding techniques including the following:


**9**

*Recent Advances in Joining of Aluminum Alloys by Using Friction Stir Welding*

iv.FSW can be automated and performed in all directions, as it is conducted

v.Parent material chemistry is free from segregation of alloying elements.

vi.Process is solid phase with process temperature regimes much lower than in fusion techniques, thus avoiding welding defects like porosity, cracking, etc.

FSW is an efficient and effective process to produce high quality welds consistently, but its performance is depending on the optimum selection of process input parameters, welding machine parameters and work material properties. Improper selection of parametric combination(s) may deteriorate the output quality parameters like mechanical properties of welded joint. Systematic analysis is required to understand the FSW process to obtain best weld qualities of weldment. The important welding input parameters which may influence the joint quality in FSW are tool's rotational speed, welding speed, welding pressure, feed rate, pin temperature, temperature distribution, downwards forging force on the tool shoulder, rotating tool torque, forces generates from the weld in welding direction and perpendicular to weld seam, etc. FSW is a relatively newly developed method, much more studies need to conduct on different aspects to utilize it economically and effectively. FSW

Friction stir welding (FSW) is a solid-state welding process created and patented by The Welding Institute (TWI) in 1991 [17]. It is a relatively novel joining technology, which has caught the interest of many industrial sectors, including automotive, aeronautic and transportation due to its many advantages and clear industrial potential. The process adds new possibilities within component design and allows more economical and environmentally efficient use of materials [18, 19]. FSW can produce low-cost and high-quality joints of heat-treatable aluminum alloys without

is attracting an increasing amount of research interest [14–16].

**2. Working principle of FSW**

*DOI: http://dx.doi.org/10.5772/intechopen.89382*

based on machine tool technology

*Weldability of different aluminum alloys [10].*

**Figure 1.**

*Recent Advances in Joining of Aluminum Alloys by Using Friction Stir Welding DOI: http://dx.doi.org/10.5772/intechopen.89382*

**Figure 1.** *Weldability of different aluminum alloys [10].*

*Mass Production Processes*

**Table 1.**

**Alloy series Major alloying element**

1xxx Pure aluminum 2xx Copper (1.9–6.8%) 3xxx Manganese (0.3–1.5%) 4xxx Silicon (3.6–13.5%) 5xxx Magnesium (0.5–5.5%)

7xxx Zinc (1–8.2%) 8xxx Others

*Various aluminum alloys and its major alloying elements [10].*

not economical as well.

are shown in **Figure 1**.

welding techniques including the following:

or filler materials for welding

as it is environment friendly

its excellent properties such as corrosion resistance [1], light in weight as having one third density of steel, machinability, thermal and electrical conductivity, easy manufacturing methods, low cost of manufacturing, etc. The applications of aluminum alloys are found in variety of applications ranging from basic to complex such as in the making of aircraft bodies [2], construction [3], structural applications [4], transportation, packing, aerospace [5, 6], automobile [4], automotive, railway, personal computers, cutlery, aeronautical and shipbuilding industries [7], naval and marine [8]. All the mentioned applications need to join, two or more parts to create one complete structure or device. Welding is one of the most widely used fabrication technique for joining similar/dissimilar parts permanently. Tungsten inert gas (TIG) and metal inert gas (MIG) welding are generally used joining methods for different materials. But, in case of welding of aluminum alloys by TIG and MIG welding processes, produces welding defects on welded joint like porosity, lack of fusion, incomplete penetration and create many cracks such as hot crack, stress corrosion [9]. Defects in the welded joints weaken the quality characteristics. Welding of aluminum alloys by TIG and MIG welding techniques are not recommended and

6xxx Magnesium and silicon (Mg 0.4–1.5%. Si 0.2–1.7%)

Friction stir welding (FSW) is an innovative welding methodology developed to join especially aluminum alloys [4] and other light-weight materials, economically [11] without any severe distortions which expected to influence mechanical and metallurgical behavior of welded sample [6, 12]. The weldability of various aluminum alloys by fusion welding methods like TIG and MIG welding, and FSW

In FSW, the job that is being welded does not melt and recast [12]. Cavaliere et al. [13] had stated that FSW is novel fabrication approach which capable to replace other joining techniques like fastener, riveted and arc welding for production of large-scale applications. FSW has various advantages over other traditional

i.The welding procedure is relatively easy, as, it does not require consumables

ii.It does not require shielding gas, no arc formation and no fumes generated,

iii.Joint edge preparation is not at all required and Oxide removal/pre-heating prior to welding is not needed, thus, welding time minimized little bit

**8**


FSW is an efficient and effective process to produce high quality welds consistently, but its performance is depending on the optimum selection of process input parameters, welding machine parameters and work material properties. Improper selection of parametric combination(s) may deteriorate the output quality parameters like mechanical properties of welded joint. Systematic analysis is required to understand the FSW process to obtain best weld qualities of weldment. The important welding input parameters which may influence the joint quality in FSW are tool's rotational speed, welding speed, welding pressure, feed rate, pin temperature, temperature distribution, downwards forging force on the tool shoulder, rotating tool torque, forces generates from the weld in welding direction and perpendicular to weld seam, etc. FSW is a relatively newly developed method, much more studies need to conduct on different aspects to utilize it economically and effectively. FSW is attracting an increasing amount of research interest [14–16].
