Experimental Investigations on Advancements of Aluminum Alloys with Friction Stir Process

Abstract

Friction stir processing is a very promising method widely joining varieties of metals in other relatively marine, shipbuilding, automotive industries, aeronautical, and heavy machinery industries due to the following advantages, such as, low porosity, less tendency to cracking, and fewer defects. Research investigates the mechanical properties for input parameters such as welding speed, rotational speed, tilt angle, and axial force, and output parameters such as tensile strength, microhardness on advancements of aluminum alloys by using friction stir processing based on cost. Taguchi L9 used for the carrying research on experiments with trailing on parent materials in different ranges of input responses on welding speed is 60 mm/min, rotational speed 1250 rpm, tilt angle 3°, and axial force of 12 KN output responses tensile strength are 167 MPa measured on the basis of ASTM on specimens and analysis for carrying and using design of experiments and mathematical modeling, the relations with empirical process useful for the development for automated design.

1. Introduction

The friction stir welding process is currently very useful for ship manufacturing and industry-oriented aircraft and automotive for butt, lap with spot-on dissimilar joining of applicability Al-alloys and other materials of Mg-alloys, the production of mass of light transportation systems and fuel consumption has significantly reduced [1]. Studied resistance of ironing with process aluminum alloys are increased to improve the silicon oxide nanoparticles for the limit of iron [2]. Studied mechanical properties and microstructural evaluation of AZ31B of sheets has 3 mm thickness welded of optimum conditions. The material of workpieces for joining friction stir processing with tool is shown in Figure 1 [3, 4]. Studies on tempered steel with quench property are feasible of tensile strength 1635 Mpa and research focus of different types of high carbon steels and medium are accepted successfully of friction stir welds. Joining of Al6061 or NiTip composite with the distribution of homogeneous particles without product interface reaction is prepared successfully by friction stir processing took place combination of good damping with thermal physical properties on the treatment of heat process in the composite [5, 6]. Al–Li 2099 T86 of stress corrosion cracking applications and [7, 8] developments of new alloy in aircraft industries are identified aluminum–lithium alloys with the [9, 10] substitute of high strength aluminum alloys on spacecraft manufacturing and launchers. The properties of strength, toughness, and [11, 12] stiffness are adopted with aluminum alloys. The aluminum–lithium alloys advanced took place with stress corrosion [13, 14] cracking on structural space applications. The parameters used for welding have [15, 16] cohesive bands and circular shapes and path studied of tool intention.

Figure 1.

Friction stir welding process.

2. Materials and methods

The friction stir process mainly involves the basic need for materials and methods influences by welding of dissimilar AA7075T651 and AA6082T651 with having thickness of 6 mm and by using advanced numerically controlled stir process are carried out experiments on the basis of lot of literature survey and trail error methods on input parameters varying with proportionate condition done at Annamalai university. Chemical compositions with base material are shown in Table 1. The specimens of the plate taken dimensions on the basis of gap is 100 mm × 50 mm × 6 mm. The dimensions cut by the edges with smooth areas to do easily joining process of butt welding for the two dissimilar aluminum alloys are placed advancing side and retreating side are shown in Figure 2 for the fixed clamps will be adjusted for specimens. The designed tool with advanced condition material taken as M2-Grade SHSS tool diameter of the shoulder is 18 mm and length of the probe is 6 mm. After the friction stir processing, the weld zone appears perfectly, for the testing of the welding specimens are taken as standards of ASTM E8 and tensile test specimens before shown in Figure 3 and specimens after testing are shown in Figure 4. The combination and particular diameter of standard specimens are taken for the impact strength shown in Figure 5. The AA7075T651 advancing side and AA6082T651 in retreating side to have the proper joining of materials and for the improvement of mechanical properties. The advanced methodology applied for different parameters to obtain easy way of influencing the properties of mechanical by using dissimilar welding of notations and units are described in Table 2 and experimental design of Taguchi model input parameters and output parameters is shown in Table 3.

Elements	Si	Fe	Cu	Mn	Mg	Cr	Ni	Zn	Ti	Al
Al7075-T651	0.12	0.2	1.4	0.63	2.53	0.2	0.004	5.62	0.03	89.26
Al6082-T651	1.05	0.26	0.04	0.68	0.8	0.1	0.005	0.02	0.01	97.03

Table 1.

The chemical compositions of AA7075T651 and AA6082T651.

Figure 2.

Weld position of dissimilar aluminum alloys of friction stir welding.

Figure 3.

Specimens of tensile test before testing with ASTM E8.

Figure 4.

Specimens of tensile test after testing.

Figure 5.

Specimens of impact test.

S. no	Parameters	Notation	Unit	Levels
				1	2	3
1	Welding speed	WS	mm/min	40	50	60
2	Rotational speed	RS	rpm	1150	1250	1350
3	Axial force	AF	KN	9	10.5	11

Table 2.

Input variables for actual and coded.

Exp. no		Input process parameters			Output responses
	Rotational speed (rpm)	Welding speed (mm/min)	Tilt angle (degree)	Axial force (KN)	Tensile strength (MPa)	Impact strength (J)	Elongation (%)
1	1150	40	1	10	162.00	10.55	9.60
2	1150	50	2	11	158.99	10.31	9.41
3	1150	60	3	12	155.00	9.00	8.50
4	1250	40	2	12	171.00	12.20	10.80
5	1250	50	3	10	164.99	11.16	10.05
6	1250	60	1	11	158.00	9.30	6.78
7	1350	40	3	11	174.99	13.10	12.15
8	1350	50	1	12	173.00	13.03	11.25
9	1350	60	2	10	167.00	11.30	10.10

Table 3.

Experimental design of Taguchi model.

3. Design of expert

The design of experts in series with the test for the researcher useful for changes in input variables on a processor system is shown in Figure 6 due to the effect of variables of responses measured. The applicability of computer simulation models and physical on the factorial designs took place sensitively for the estimation of the combination of effect for two or more factors.

Figure 6.

Process model of the design of expert.

The design of experiments and methods of the traditional difference taken place approach in a better way of values on variables of parallel and it does not cover the main effects on the variables on the different interactions and the possibility of approach for identifying optimal values on the variables of combination with experimental runs. The design of experiments is carried out in four phases: Screening, Planning, Optimization, and Verification.

The influence of rotational speed on tensile strength has increased based on the tool welding speed varies the strength with respect to the elongation has improved to the maximum extent depends on the rotational speed. Figure 7 shows the increases in rotational speed depends on the heat increases at the welding zone area. The friction coefficient decreases with the melting condition. The friction stir process region intricate the fine particles will be distributed in the uniform portion. The effect of tool stirred the position on the flow of metal optimum depends on the increase of tensile strength.

Figure 7.

Influence of rotational speed on tensile strength.

The percentage of elongation along transverse direction obtained from the tensile test plotted against the welding speed. The plates (Figure 8) shows welded with a rotational speed of 1250 rpm and weld speed of 40 mm/min. While the plates were welded at 1150 rpm and 60 mm/min. The influence shows the properties of higher heat input on the basis of influenced elongation.

Figure 8.

Influence of welding speed on tensile strength.

The influence of tilt angle on tensile strength (Figure 9) shows the manner of the position at the bottom area of the welded part and it will increase the position of tool speed with respect to the material and designed shoulder based. The region of the position will make difference between the tool changes the yield strength to improve the microstructure with ductility.

Figure 9.

Influence of tilt angle on tensile strength.

The influence of axial force on tensile strength (Figure 10) shows the significance of friction stir processing at the joining area. The joint took place in the position of rotational speed is 1250 rpm and tensile strength 164.99 MPa and the welding speed takes the major role due to increasing of force is 12 KN has the strength will be superior at the position of part counter.

Figure 10.

Influence of axial force on tensile strength.

The influence of rotational speed on impact strength produces Figure 11 shows the frictional heat required to plasticize the material and also the effect of proper mixing of the dissimilar alloys. The changes in the position of the part speed will be low and have good mechanical properties at the welding speed is higher.

Figure 11.

Influence of rotational speed on impact strength.

The influence of welding speed on impact strength shows Figure 12 maintains the region with the center point of the notch makes the higher energy in order to analyze the impact energy at an instant with the increasing of welding speed 60 mm/min and impact energy of the notch shows 9.2 J.

Figure 12.

Influence of welding speed on impact strength.

The influence of tilt angle on impact strength shows Figure 13 increases of the impact energy with 11 J with respect to the tilt angle 3° will be maximum of increasing tool tilt angle.

Figure 13.

Influence of tilt angle on impact strength.

The influence with axial force on impact strength Figure 14 shows the tool stirring action plays a major role of the part to increase the rotational speed with the resultant of the weld area. The surfaces that occur groove condition because insufficient material will be visible. The zone of the weld part decreases with rotational speed due to the effect of distribution with temperature at the area of weld zone.

Figure 14.

Influence of axial force on impact strength.

The influence of rotational speed on elongation shows in Figure 15 with the increase of rotational speed on the higher input of heat. The position of the tool will be the friction decreases with the heat input condition. The friction stir processing is the best condition for the optimized region on the fine particles with the distribution of uniform.

Figure 15.

Influence of rotational speed on elongation.

The percentage of elongation along transverse direction obtained from the tensile test plotted against the welding speed. Figure 16 shows plates welded with rotational speed is 1250 rpm and weld speed of 40 mm/min. While plates welded rotational speed is 1150 rpm and welding speed 60 mm/min. The proportion area influences the heat input due to the elongation of 11.25%.

Figure 16.

Influence with welding speed on elongation.

The influence of tilt angle on elongation shown in Figure 17 is the position of tool depends on the material adjustment at the shoulder region of the part condition varies with the improvement condition in a friendly environment at the joining portion of the yield works due to the microstructure will give perfect condition in the region of the part due to tilt angle maximum 3° and elongation of 9.7%.

Figure 17.

Influence of tilt angle on elongation.

The influence of axial force on elongation shows in Figure 18 with the flow of zone part due to higher heat input it occurs at the probe area. The tool pin changes the position in order to move the actual flow of material to control the plastic deformation easily. The shoulder will be the major portion force will increase the depth level of plunge working the linear position. The axial force increases the due to increase of the pressure at a higher extent the shoulder area will be stirred normal position easily.

Figure 18.

Influence of axial force on elongation.

4. Conclusions

The present investigation shows the aluminum alloys with the application of Taguchi design of experiments helped us in conducting the experiments in an effective manner without losing accuracy. Two-dimensional plots are plotted between the input process parameter and the output responses using Design-Expert software. The tensile strength is increasing with the increase in rotational speed and the axial force values and the tensile strength is decreasing with the increase in the weld speeds. The impact strength increases, when there is an increase in the values of rotational speed and axial force. Whereas the impact strength tends to decrease with the increase in the weld speeds. The elongation also increases with the increase in rotational speed and axial force. The results presented in the work are analyzed on the basis of analysis process conducted with microstructures with different zones on thermo mechanical treatment zone has higher plasticity due to eutectic constituents Cu–Al precipitation on rolled condition and parent metal has rolled temper condition.