The Influence of Process Parameters on the Temperature Profile of Friction Stir Welded Aluminium Alloy 6063-T6 Pipe Butt Joint

Available at http://link.springer.com/chapter/10.1007/978-3-319-19443-1_19

The Influence of Process Parameters on the Temperature Profile

of Friction Stir Welded Aluminium Alloy 6063-T6 Pipe Butt Joint

Azman Ismail1*

, Mokhtar Awang2a

, Shaiful Hisham Samsudin2b

1Universiti Kuala Lumpur Malaysian Institute of Marine Engineering Technology,

Jalan Pantai Remis, 32200 Lumut, Perak, Malaysia.

Tel:+605-690 9000, Fax: +605-690 9091.

Email: [email protected]*

2Department of Mechanical Engineering, Universiti Teknologi PETRONAS,

Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia.

Tel:+605-368 8000, Fax: +605-365 4075.

Email: [email protected]; [email protected]

b

Abstract

The temperature profile of friction stir welded aluminum alloy 6063-T6 pipe joints will be

investigated in this paper. A pipe with an outside diameter of 89mm and a wall thickness of

5mm will be used as test pipe piece for this experiment on closed butt joint configuration

by utilizing a Bridgeport 2216 CNC milling machine and orbital clamping unit which is

specially-designed to cater for this task and function. Several samples will be prepared with

varying process parameters such as rotational speed and travel speed. A very simple tool

was used with a flat shoulder and a cylindrical pin. An infra-red thermometer will be


employed to assess the temperature profile of the friction stir welded pipe butt joints during

the experiment. The correct selection of process parameters will lead to a better joining

condition of the welded joint. Several good samples were produced by this experiment

setting.

Keyword(s): Temperature profile, AA6063-T6 pipe, butt joint, friction stir welding,

Bridgeport 2216 CNC milling machine,

1 Introduction

This solid state joining process was invented by Wayne Thomas from The Welding

Institute, United Kingdom in 1991. This process is called as friction stir welding (FSW).

FSW utilizes heat from friction to soften the adjoining section and then these sections are

stirred together soundly as shown in Fig. 1 [1].

This welding process requires no filler metal and shielding gas, producing no arc and

fumes. This FSW was initially developed to cater to the problem found in arc welding for

aluminium such as distortion, shrinkage, and porosity. The implementation of FSW

prevents such problems from occurring. This welding technique has been used for many

applications due to lightweight construction, cost saving and environmental protection [2].

Pipe joining for FSW introduced complex challenges due to its tubular shape. Not many

studies have been done for pipes instead of flat panels. Therefore, in order to run the


experiment successfully, a proper fixture is vital. Several successful methods were

introduced by previous studies [1,3,4,5,6] . This will become the basic reference of the new

built fixture called the orbital clamping unit (OCU). Hence, it is necessary to enable the

available Bridgeport 2216 unit, a CNC milling machine, to run as a FSW unit for pipe

joining.

It is important to understand the temperature profile in the pipe piece as it

determines the success of the joint to be made, residual stress imposed, grain size and the

strength of the welds [7]. The welding parameters for a successful FSW process will be

discussed and the temperature profile at the tool will be measured in this present study.

2 Experimental Setup

An experimental setup is shown in Fig. 2. The pipe with an outside diameter of 89 mm and

a 5 mm wall thickness was used in this present study. The tool was made of surface-

hardened high carbon steel H13 with 20 mm diameter of shoulder length, a pin diameter of

5 mm and 3.8 mm of pin length. The tool was positioned with a 6mm forward offset from

the centerline [1,8,9].

The welding parameters used were shown in Table 1. The plunge depth and dwell time

used were 4 mm and 30 s respectively. Chemical composition and mechanical properties

are shown in Table 2 and 3 respectively [10]. The infrared (IR) thermometer was used to


measure the temperature profile at the rotating tool for further analysis. All samples were

inspected based on the AWS D17.3 acceptance level [11].

3 Results and Discussion

An IR thermometer was used to measure the temperature profile of the full weld cycle. The

IR thermometer was shot on the rotating tool shank. The outer surface of the aluminium

pipe was too reflective therefore the tool shank was used as point of measurement of

temperature [1]. Figures 3 and 4 show the temperature profile measured for certain welding

parameters, with the increment of rotation speed at constant travel speed and with the

increment of travel speed at constant rotation speed, respectively.

Based on the Fig. 3, the increment of rotation speed increases as the temperature generated

from this friction process along the weld joint increases. Higher rotation speed generally

generates higher temperatures. However, the recorded temperature profile varies due to

pipe eccentricity, therefore causing a variation in contacts between the tool's shoulder and

the outer pipe surface thus giving different temperature readings during the experiment. It

was also dependent on the tool's offset setting from the axis of rotation. The measured

temperature varies between 106.4oC and 289.1

oC. A constant temperature was not detected

during the experiment. As noted, the temperature increases in variation throughout the weld

cycle. This quite similar temperature pattern was observed by a previous study [1,5,7].


Based on the Fig. 4, the temperature is decreasing with the increment of travel speed and

off course these readings differ due to the same reason as before; i.e. the pipe eccentricity

which affects the friction contact between tool's shoulder and the outer pipe surface. The

measured temperature is between 130.9oC and 285.9

oC. The increment of travel speed

causes less time spent at a certain temperature level hence causing the reduction in

generated temperatures.

For both experiment settings, the variation in temperature did affect the weld surface

roughness quality as shown in Fig. 5. The issues of secondary heating can be seen on both

settings as shown in Figs. 2-3 respectively as the tool starts and stops at the same point in

order to complete the weld cycle, which previously underwent heat treatment.

4 Conclusion

Based on the present study, the following conclusions can be made;

1) With the increment of rotation speed at constant travel speed, the temperature will

increase, which was measured to be between 106.4 oC to 289.1

oC.

2) With the increment of travel speed at constant rotation speed, the temperature will

decrease, which was measured to be between 130.9 oC and 285.9

oC.

3) The plowing effect can be achieved by offsetting the tool from its axis of rotation.

4) The variation in temperature did affect the weld surface quality (roughness).

5) The variation in temperature measurements for both welding parameters are due to

pipe eccentricity which caused contact fluctuation in heat generation.


6) Secondary heating occurred in friction stir welded pipe joining.

7) Tool-surface contact fluctuated within an acceptable range during the weld cycle.

5 Acknowledgment

The authors thank the Universiti Kuala Lumpur for providing the conference grant, 452-

520435(004) and the Department of Mechanical Engineering, Universiti Teknologi

PETRONAS for providing the required facilities and assistances.

References

[1] Lammlein DH, Gibson BT, DeLapp DR et al (2010), Friction Stir Welding of Small

Diameter Pipe: An Experimental and Numerical Proof of Concept for Automation and

Manufacturing. Proc. Inst. Mech. Eng., Part B, pp1-16.

[2] Kumar A, Fairchild DP, Macia ML et al (2011), Evaluation of Economic Incentives and

Weld Properties for Welding Steel Pipelines Using Friction Stir Welding, Proc. Int.

Offshore Polar Eng. Conf., pp460-467.

[3] Packer S. M. and Matsunaga M (2004), Friction stir welding equipment and method for

joining X65 pipe, Proc. Int. Offshore Polar Eng. Conf., pp55-60.

[4] Jeffrey Defalco and Russell Steel (2009), Friction Stir Process Now Welds Steel Pipe,

Welding Journal, American Welding Society, Vol. 88, No. 5, pp44-48.


[5] Gercekcioglu E, Eren T, Yildizh K et al (2005), "The friction behavior on the external

surface of the friction stir welding of AA6063-T6 tubes", The 5th Int Conf on

Tribology, pp225-228.

[6] Qasim M Doos, and Bashar Abdul Wahab (2012), "Experimental study of fricton stir

welding of 6061-T6 aluminium pipe", IJMERR, Vol.1, No.3, pp143-156.

[7] Yeong-Maw Hwang, Zong-Wei Kang, Yuang-Cherng Chiou, and Hung-Hsiou Hsu

(2008), "Eperimental study on temperature distributions within the workpiece during

friction stir welding of aluminum alloys", Int J Mach Tool Manu, Vol. 48, Issues 7-8,

pp778-787.

[8] Azman Ismail, Mokhtar Awang, Hasan Fawad, and Kamal Ahmad (2013), "Friction stir

welding on aluminum alloy 6063 Pipe, Proceedings of the 7th Asia Pacific IIW

International Congress, pp78-81.

[9] Azman Ismail, and Mokhtar Awang (2014), "Surface hardness of friction stir welded

AA6063 pipe, MATEC Web of Conferences, Vol. 13, 04025, pp1-5.

[10] Aalco Metals Ltd, "Aluminium alloy 6063-T6", www.aalco.co.uk.

[11] AWS D17.3, "Specification for friction stir welding of aluminium alloys for

aerospace application", American National Standard Institute, 2010.


List of figures;

Figure # Caption

Fig. 1 FSW process

Fig. 2a FSW setup - front view

Fig. 2b FSW setup - side view

Fig. 3 Temperature profile FSW#1-3

Fig. 4 Temperature profile FSW#3-5

Fig. 5 Surface roughness of FSW samples


Fig. 1: FSW process.


Fig. 2a: FSW setup - front view


Fig. 2b: FSW - side view


Fig. 3: Temperature profile for FSW#1-3

(variation in rotation speed at constant travel speed)

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300

Tem

pe

ratu

re, o

C

Distance, mm

FSW #1

FSW #2

FSW #3


Fig. 4: Temperature profile for FSW#3-5

(variation in travel speed at constant rotation speed)

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300

Tem

pe

ratu

re, o

C

Distance, mm

FSW #3

FSW #4

FSW #5


Fig. 5: Surface roughness of FSW samples

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

1 2 3 4 5

Surf

ace

ro

ugh

ne

ss, µ

m

FSW Sample Number#


List of tables;

Table # Caption

Table 1 FSW welding parameters

Table 2 Chemical composition of AA6063-T6 pipe

Table 3 Mechanical properties of AA6063-T6 pipe


Table 1: FSW welding parameters

FSW sample Welding parameters

Rotation Speed (rpm) Travel Speed (mm/s)

FSW#1 900 1.2

FSW#2 1200 1.2

FSW#3 1500 1.2

FSW#4 1500 1.8

FSW#5 1500 2.4


Table 2: Chemical composition of AA6063-T6 pipe


Table 3: Mechanical properties of AA6063-T6 pipe

Documents

The Influence of Process Parameters on the Temperature Profile of Friction Stir Welded Aluminium Alloy 6063-T6 Pipe Butt Joint