International Journal of Scientific & Engineering Research, Volume 3, Issue 11, November-2012 1

ISSN 2229-5518

Effect of tool on tensile strength in single and double sided friction stir welding.

Sunny Mehra1, Pardeep Dhanda2 , Ravinder Khanna3 ,Narender Singh Goyat4 Sanjeev Verma5

1 Research Scholar, 2Research Scholar, 3Professor, 4Assistant Professor

1 Department of Mechanical Engineering, PCET, Lalru (Punjab)

Email:sunnymehra560@gmail.com

2Department of Mechanical Engineering, PCET, Lalru (Punjab)

3 Department of Mechanical Engineering, PCET, Lalru (Punjab)

4Department of Mechanical Engineering, ASET, Bijwasan,New Delhi

Email: nr.goyat@gmail.com

5Department of Mechanical Engineering, PCET, Lalru (Punjab)

Abstract - In this experimental work, an extensive investigation had been carried out on AL

19000-H12 grade aluminum alloy plates. Plates of aluminum alloy (AL19000H12) size 200x50x6 mm were used for experiment. Material of weld tool used high carbon steel Diameter of tool head used 17 mm and length 50mm. Four different tool pin profiles (Straight cylindrical, Square, Threaded and Triangular) be used to fabricate joints in a single and sequential double sided. In this investigation, tool rotation and traverse speeds be kept constant i.e. 3000 rpm and 25 mm/min. The variables are shape of the tool and having passes one sided and both sided. Tensile test specimens are prepared according to the guidelines of American Society for Testing of Materials (ASTM) to be tested on UTM (Ultimate tensile strength). Ultimate tensile strength, percentage elongation and joint efficiency are noted. Various mechanical properties of the joints are evaluated.

Keywords: - AL19000H12, Join efficiency, Percentage elongation, Tensile strength, UTM.

1 INTRODUCTION

In this investigation, an attempt has been made to establish relationship between the base material properties and FSW process parameters. FSW is a solid state welding process for joining aluminum alloys and has been employed in aerospace, rail, automotive and marine industries for joining aluminum, magnesium, zinc and copper alloys. In FSW, the base metal properties such as yield strength, ductility and hardness control the plastic flow of the material under the action of rotating non-consumable tool.
Several previous studies reported the effects of the tool threads and probe profile on different aluminum alloys. In spite of these achievements, the effect of tool shape on mechanical properties in single and sequential double sided friction stir welds of aluminum alloy AL19000 has not yet been systematically classified. Additionally, in order to design effective tools of high carbon steel to precede FSW on aluminum alloys, new concept is necessary. The tool requires the following characteristics:
1. As simple a shape as possible to reduce cost

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2. Sufficient stirring effect to produce sound welds.
Hence an attempt has been made to study the effect of influence of tool shape on the mechanical properties (tensile strength) of AL19000 in single and double sided friction stir welds in this project.

2 EXPERIMENTAL METHODOLOGY

2.1 Friction Stir Welding:-

Friction stir welding also produces a plasticized region of material, but in a different manner. The plates to be welded are butted together and clamped to a rigid backing plate. A non consumable rotating tool is pushed into the material to be welded. Then the central pin, or probe followed by the shoulder is brought in to contact with the two parts to be joined. The rotation of the tool heats up and plasticizes the material which is in contact with it. As the tool moves along the joint line, material from the front of the tool is swept around this plasticized annulus to the rear so eliminating the interface.

Fig.1 Friction Stir Welding

In general, the process is robust and a wide range of processing parameters and tool
designs can be used to make metallurgical sound welds in a given alloys and plates thickness while using a wide range of processing parameters, the chosen process parameters may significantly affect the mechanical properties of weld through direct modification of weld microstructure.

3 EXPERIMENTAL SETUP AND PROCESS PARAMETERS SELECTED

3.1 Work piece material and composition The base material (BM) used in this investigation is aluminum alloy AL19000. AL19000 having mechanical properties like Tensile strength (110Mpa), Yield strength (105MPa) and Elongation up to 12 %.Plates of aluminum alloy (AL19000H12) size

200x50x6 mm were used for experiment. The chemical composition of AL 19000
Cu(0-0.1), Mn(0-0.1), Si(0-0.5), Fe(0-0.6)
and Min.99% Al.

3.2 Selection of Tool for experiment

High carbon steels used for welding. Diameter of tool head used 17 mm. Different shapes of tools being used for single side FSW dimensions are given below
1. Straight Cylindrical (SC) – pin diameter-5mm and pin length – 5.5 mm
2. Square (SQ)- pin dimensions – (5x5)mm , diagonal 7 mm and pin length – 5.5 mm
3. Cylindrical Threaded (TH) – pin diameter 6mm , pitch of thread- 0.7 mm, pin length- 5.5 mm
4. Triangular (TR) – diagonal – 5mm , pin length- 5.5 mm

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Fig2. Different shapes of tools being used for FSW
Similarly four shapes of tools being used for double sided FSW dimensions are given below
1. Straight Cylindrical (SC) - pin diameter-5mm and pin length -3 mm
2. Square (SQ) - pin dimensions – (5x5)mm, diagonal 7 mm and pin length-3 mm
3. Cylindrical Threaded (TH)- pin diameter 6mm, pitch of thread- 0.7 mm, pin length-3 mm
4. Triangular (TR) – diagonal – 5mm , pin length- 3 mm

3.3 Experimental work

Machine tool used for FSW operation is
vertical milling machine of following specifications.

Before testing welded specimen (single and double sided) were assigned number as single sided welded specimen assigned odd number and double sided welded specimen assigned even numbers.
Figure 3 Vertical milling machine used for
FSW operation

Sr. No.

Specimen name

Type of weld pass

Tool shape

1

S1

Single

Straight cylindrical

2

S2

Double

Straight cylindrical

3

S3

Single

Square

4

S4

Double

Square

5

S5

Single

Cylindrical threaded

6

S6

Double

Cylindrical threaded

7

S7

Single

Triangular

8

S8

Double

Triangular

9

S9

Base metal

-

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1. TENSILE TEST RESULTS OF BASE METAL (Notch Tensile Strength)

Specimen

No.

Dimension

Ultimate Tensile Strength

Percentage Elongation

Specimen

No.

Area

(mm2)

Load

(kgf)

Stress

(N/mm2)

Elongated

Length (mm)

%

Elongation

S-9

14.48x6

1280

144

52.48

4.96

2. TENSILE TEST OF WELDED SPECIMENS IN SINGLE PASS (Notch Tensile

Strength)

Specimen

No.

Ultimate Tensile

Strength

Percentage Elongation

Joint

Efficiency

Specimen

No.

Area

(mm2)

Load

(kgf)

Stress

(N/mm2)

Elongated

Length (mm)

%

Elongation

Joint

Efficiency

S-1

14.75x6

828

91.75

52.21

4.42

63.71

S-3

15.35 x6

920

97.96

56.73

13.46

68.00

S-5

15.60 x6

824

86.33

53.27

6.54

59.95

S-7

15.20 x6

830

89.25

53.64

7.28

61.97

3. TENSILE TEST RESULTS OF WELDED SPECIMENS IN DOUBLE PASS (Notch Tensile Strength)

Specimen

No.

Ultimate Tensile Strength

Percentage Elongation

Joint

Efficiency

Specimen

No.

Area

(mm2)

Load

(kgf)

Stress

(N/mm2)

Elongated

Length (mm)

%

Elongation

Joint

Efficiency

S-2

14.88x6

880

96.66

54.73

9.46

67.13

S-4

15.30 x6

964

102.98

56.82

13.64

71.51

S-6

14.85x6

932

102.57

55.82

11.64

71.23

S-8

14.70 x6

816

90.73

54.70

9.4

63

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4 RESULT AND DISCUSSION:-


this trend is common for all the tool profiles.
ii. For the straight cylindrical pin profile tool, crack like defects are found in both single and double pass joints.
iii. Square pin tool having inferior tensile strength in both single sided
and double sided FSW.
In this investigation an attempt has been made to study the effect of tool pin profile (straight cylindrical, threaded, triangular and square) on the formation of friction stir processing zone in a single and sequential double sided friction stir weld in AL19000. From this investigation, the following important conclusions are derived:
i. The joints fabricated by double passes have shown higher ultimate tensile strength and also percentage of elongation as compared to the
joints fabricated by single pass and

5 CONCLUSIONS

From this investigation, the following important conclusions are derived:
(i) The joints fabricated by double passes have shown higher ultimate tensile strength and also percentage of elongation as compared to the joints fabricated by single pass and this trend is common for all the tool profiles.
(ii) Square pin tool having inferior tensile strength in both single
sided and double sided FSW.

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ISSN 2229-5518

REFERENCES

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