Optimization of Process Parameter of FSP Cladded AZ31B Magnesium Alloys

(1)

ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013

46

Optimization of Process Parameter of FSP Cladded AZ31B Magnesium Alloys

K. Ganesa Balamurugan & K. Mahadevan

Dept. of Mechanical Engineering, Pondicherry Engineering College, Pondicherry -605014, India.

E-mail : [email protected], [email protected]

Abstract – Al5086 aluminium alloy was successfully cladded on the AZ31B magnesium alloy using friction stir processing. The experiments were conducted as per Taguchi mixed design model. The mechanical and tribological tests were conducted as per ASTM standards.

Taguchi method optimization was used to optimize the responses and ANOVA technique was used to identify the significant factor for each responses.

Index Terms— Aluminium cladding, AZ31B magnesium alloy, ANOVA, FSP, Taguchi method.

I. INTRODUCTION

Light weight metallic alloys are the primary concern of the present day automotive, aerospace and electronic industries [1-3]. The magnesium alloys satisfy the above desire of the industries by its low density and high specific strength [4-6]. However, the formability and the tribological properties of magnesium alloys are not commendable [7-8]. To overcome these limitations many researchers attempted to modify the surface of the bare magnesium alloys with several coating techniques like electrochemical plating, conversion coating, plasma coating and anodizing [9]. Recently some researchers have identified friction stir processing (FSP) as a unique surface modification technique [10-11]. In the present work an attempt was made to clad Al5086 aluminium alloy on AZ31B magnesium alloy using friction stir processing. Taguchi method of optimization was used to find the optimum parameter set for each response and ANOVA technique was used to identify the significant factor for each response.

II. EXPERIMENTAL PROCEDURE

Commercially available AZ31B magnesium alloy and marine grade Al 5086 aluminium alloy plates were

used in this study. The specimen size of AZ31B alloy was 40x100x6 mm and the specimen size of Al5086 alloys was 38x100x2 mm. A groove of size 38x100x1.5 mm was taken in the AZ31B alloy and the Al5086 alloy clad plate was placed in it for proper contact between the two plates. CNC vertical milling center was used to perform the FSP on the plates. A concave shoulder tool of 18mm shoulder diameter and 5mm pin diameter with strait flutes was used. The tool material was HCHCr hardened to 58 HRC. The processing Al5086 alloy placed on AZ31B magnesium plates were clamped on the machine table using a fixture. After activation of preset program in the CNC machining center, the tool performed the FSP on the specimens to clad Al5086 aluminium alloy with AZ31B magnesium plate. A constant tool depth of 4.2mm was maintained throughout the process. The tool rotational speed and tool travel speed values used are given in the Table.1 and Table.2 shows the mixed Taguchi’s L8 orthogonal array experiment design. The FSP operation was carried out on AZ31B magnesium alloy without cladding of Al5086 alloy with same process parameter values for comparison. The processed specimens were subjected to mechanical tests and tribological tests as per ASTM standards. Tensile tests were conducted as per ASTM B557; Micro hardness test was performed as per ASTM E384. Corrosion tests were conducted as per ASTM G59-97e1 and Wear tests were conducted as per ASTM G99.

Table.I Process parameters and their values Tool Rotational Speed in

[RPM]

Tool Travel Speed in [mm/min]

500 710 850 1000 14 20

(2)

International Journal on Mechanical Engineering and Robotics (IJMER)

47 Table.II Experimental Design

Exp.

No.

Tool Rotational Speed [RPM]

Tool Travel Speed [mm/min]

01 500 14

02 500 20

03 710 14

04 710 20

05 850 14

06 850 20

07 1000 14

08 1000 20

III. RESULTA AND DISCUSSION

Table.III shows the results of the Al5086 cladded AZ31B magnesium alloys.

Table.III Experimental Results Exp.

No.

Tensile Strength

(MPa)

Microhardness (Hv)

Corrosion Rate (mm/yr)

Wear Losses (mg)

01 205 80.4 8.27E-07 1.10

02 236 120 1.86E-06 0.70

03 185 82.2 1.10E-06 0.95

04 215 80.7 9.70E-06 1.08

05 181 86.8 1.52E-06 0.87

06 142 83.4 1.75E-06 0.90

07 166 80.5 0.000286 0.94

08 174 91.6 0.003522 0.83

A. Optimization

Taguchi method of optimization is used to optimize the process parameters sets.

For Corrosion rate and Wear Losses Smaller the Better strategy is used

For Tensile strength and Microhardness Larger the Better strategy is used

Formula for smaller the better strategy is S/N= -10 x log ((1/n)ΣYi);

Formula for larger the better strategy is S/N= -10 x log (1/(n*ΣYi));

Fig.1 Shows the S/N ratios of the responses The following Table.IV shows the optimized parameter set for each response

(3)

48 Table. IV Optimized parameter set for each response

Response Strategy Optimized parameter set Tensile

strength

Larger the

Better 500 rpm-20 mm/min Microhardness Larger the

Better 500 rpm-20 mm/min Corrosion

Rate

Smaller the

Better 500 rpm-14 mm/min Wear losses Smaller the

Better

500 m-20 mm/min B. Identification of significant factor

The significant factor of this experiment was identified using ANOVA technique. Using Minitab software, for α=0.05 significance, the ANOVA tables were generated. Table V, Table VI, Table VII, Table VIII show the ANOVA results of the Tensile strength, Microhardness, Corrosion rate and Wear losses respectively.

Table.V ANOVA for Tensile Strength

Source DF SS MS F F

Critical Rotational

Speed

3 8894.3 2964.75 1824.75 4.07

Travel Speed

1 210.3 210.25 129.38 5.32

Interaction 3 3228.3 1076.08 662.21 3.84 Residual 8 13.0 1.63

Total 15 12345.8

Table.VI ANOVA for Microhardness

Speed

3 1040.90 346.96 1.35E+15 4.07

Travel Speed

1 627.50 627.50 2.45E+15 5.32

Interaction 3 1728.48 576.16 2.25E+15 3.84 Residual 8 0.00 0.00

Total 15 3396.89

Table.VII ANOVA for Corrosion rate

Speed

3 1.166E-05 3.88E- 06

802.559 4.07

Travel Speed

1 24.50 24.50 5.05E+09 5.32

Interaction 3 -24.50 -8.167 -1.6E+09 3.84 Residual 8 3.87E-08 4.84E-

09 Total 15 2.30E-05

Table.VIII ANOVA for Wear losses

Speed 3

2.42 8.07E-

16 1.424 4.07

Travel Speed

1

24.50 24.50 4.3E+16 5.32 Interaction 3 -

24.50 -8.16 1.44E+16 3.84 Residual 8

4.534 5.67E-

16 Total 15 7.24

Table IX shows the summarized results of ANOVA.

Table IX Significant factors for the responses Responses Significant Factor Tensile Strength Rotational Speed

Microhardness Travel Speed Corrosion Rate Travel Speed

Wear losses Travel Speed

IV. CONCLUSION

In this work an attempt was made to clad Al5086 aluminium alloy on AZ31B magnesium alloy using friction stir processing. Taguchi method of optimization was used to find the optimum parameter set for each response and ANOVA technique was used to identify the significant factor for each response. The following results were obtained;

1. For responses like Tensile strength, Microhardness and Wear losses 500 rpm-20 mm/min parameter set was identified as optimum set.

2. For Corrosion rate 500 rpm-14 mm/min parameter set was identified as optimum set.

(4)

49 3. For Tensile strength, rotational speed was identified

as significant factor.

4. For Microhardness, Corrosion Rate and Wear losses, travel speed was identified as significant factor

V. REFERENCES

[1] Yu Sirong, Chen Xianjun, Huang Zhiqiu, Liu Yaohui: Journal of rare earths Vol. 28, No. 2 (2010), p.316.

[2] Mordike B L, Ebert T: Materials Science and Engineering A Vol. 302 (2001), p 37.

[3] Kinji Hirai, Hidetoshi Somekawa, Yorinobu Takigawa, Kenji Higashi: Materials Science and Engineering A Vol.403 (2005), p276.

[4] Parviz Asadi & Ghader Faraji & Mohammad K.

Besharati: Int J Adv Manuf Technol Vol. 51 (2010), p247.

[5] Morisada Y, Fujji H, Nagaoka T, Fukusumi M:

mater. Sci Eng A Vol. 433 (2006), p50.

[6] Darras BM, Khraisheh MK, Abu-Farha FK, Omar MA: Mater Proc Tech Vol.191 (2007), p77.

[7] P. Cavaliere, P.P. De Marco: Materials Science and Engineering A Vol.462 (2007), p393.

[8] A. Rudajevov´a, M. Stanek, P. Luk´aˇc, Mater.

Sci. Eng. A 3Vol.41 (2003), p152.

[9] Duck Y. Hwang1, Jin Y. Cho, Dong H. Lee, Bong Y. Yoo and Dong H. Shin: Materials Transactions, Vol. 49, No. 7, (2008), p.1600.

[10] S. Mironov, Q. Yang, H. Takahashi, I. Takahashi, K. Okamoto, Y.S. Sato, and H.Kokawa: The Minerals, Metals & Materials Society and ASM International Vol. 41A (2010), p1016

.[11] R.S. Mishra, M.W. Mahoney, S.X. McFadden, N.A. Mara, and A.K. Mukherjee: Scripta Mater.

vol. 42 (2000), p163.

