Experimental Investigation of the Corrosion Behavior of Friction Stir Welded AZ61A Magnesium Alloy Welds under Salt Spray Corrosion Test and Galvanic Corrosion Test Using Response Surface Methodology
Table 4
Design matrix and experimental results.
EX. no.
Coded values
Actual values
Corrosion rate (salt spray tests) (mm/yr)
Corrosion rate (galvanic corrosion tests) (mm/yr)
pH
Time
Conc.
pH
Time (hour)
Conc. (Mole)
1
−1
−1
−1
4.62
2.62
0.36
14.62 (0.11)
0.0397 (0.16)
2
+1
−1
−1
9.38
2.62
0.36
10.23 (0.56)
0.0254 (0.13)
3
−1
+1
−1
4.62
7.38
0.36
11.89 (0.21)
0.0340 (0.20)
4
+1
+1
−1
9.38
7.38
0.36
8.99 (0.18)
0.0111 (0.18)
5
−1
−1
+1
4.62
2.62
0.84
15.82 (0.16)
0.0456 (0.14)
6
+1
−1
+1
9.38
2.62
0.84
11.31 (0.1)
0.0425 (0.1)
7
−1
+1
+1
4.62
7.38
0.84
12.92 (0.26)
0.0519 (0.52)
8
+1
+1
+1
9.38
7.38
0.84
10.75 (0.05)
0.0376 (0.05)
9
−1.682
0
0
3
5
0.60
17.96 (0.26)
0.0612 (0.08)
10
+1.682
0
0
11
5
0.60
6.88 (0.41)
0.0267 (0.11)
11
0
−1.682
0
7
1
0.60
11.23 (0.56)
0.0598 (0.07)
12
0
+1.682
0
7
9
0.60
8.51 (0.42)
0.0282 (0.11)
13
0
0
−1.682
7
5
0.20
6.66 (0.23)
0.0184 (0.05)
14
0
0
+1.682
7
5
1
15.28 (0.4)
0.0534 (0.08)
15
0
0
0
7
5
0.60
9.89 (0.36)
0.0432 (0.03)
16
0
0
0
7
5
0.60
8.56 (0.02)
0.0365 (0.02)
17
0
0
0
7
5
0.60
9.79 (0.03)
0.0370 (0.21)
18
0
0
0
7
5
0.60
9.97 (0.05)
0.0377 (0.24)
19
0
0
0
7
5
0.60
8.93 (0.04)
0.0379 (0.38)
20
0
0
0
7
5
0.60
9.62 (0.09)
0.0381 (0.12)
The values presented in brackets are the standard deviation.
