EFFECT OF ALLOYING ADDITIONS AND AGING CONDITIONS ON THE HARDNESS (HB) OF 319 (ALUMINUM) ALLOYS

By Andi Firdaus SudarmaID No.: 432107963

ME-508 Experimental Methods in MEDR. Basharat Salim (Lecturer)

INTRODUCTION

Table 1. Chemical composition limits of aluminum 319. [3]

EXPERIMENTAL DESIGN

Experimental Procedure

Ingot Melting

Adding Alloys

Pure Argon Degassing

CastingHeat

Treatment (8h@495OC)

Quenching (Water@65O

C)Aging

Hardness Measuremen

t

Heat Treatment and Aging Scheme

Experimental Aging Matrix

H1: aging at 180oC up to 2 hours.

H2: aging at 180oC up to 8 hours.

H3: aging at 220oC up to 2 hours.

H4: aging at 220oC up to 8 hours.

DATA & RESULT

Data ResultAlloy Code

Factors Combination Aging Condition

%Mg %V.F Sr-ppm H1 H2 H3 H4

18 - - - 117 119 108 103

20 + - - 131.5 132.5 119 116

19 - + - 117.5 123 106 101

21 + + - 137.5 133.5 127 112

18s - - + 108.5 109 94 96.5

20s + - + 120.5 119 114 99

19s - + + 117.5 115 96 95.5

21s + + + 127 128.5 116 101.5

Notation•%Mg (+) maximum value of magnesium contains (~0.27%) (-) minimum value of magnesium contains (~0.1%)•%V.F(+) Fe-type morphology: α-Fe and β-Fe

(-) Fe-type morphology: α-Fe•Sr-ppm (+) Strintium modified

(-) No modification

Anova Table

Source of Variation

Sum of Square

Degree of Freedom

Mean

Square

Fo Ft

Alloy2131.59

47

304.513

24.077

2.51

Aging Condition

2177.406

3725.80

257.38

73.10

Non Addivity

5.766 1 5.766 0.456 4.35

Error 252.952 20 12.648

Total4567.71

931

Hypothesis

•With confidence level at 95%, non addivity comparison of F value, we have Fo < Ft, so the null hypothesis is accepted. It mean that there is no interaction between treatment A and B. If there is no interaction then (τβ)ij = 0 for all i and j.

•Comparing the F value that we get from observation and F value from table, the correlation is Fo > Ft, it mean that there significant mean effect of treatment A and treatment B.

Plot of Hardness vs. Aging Condition

1 2 3 480

90

100

110

120

130

140

150

Alloy 18Alloy 20Alloy 19Alloy 21Alloy 18sAlloy 20sAlloy 19sAlloy 21s

Har

dnes

s

Aging Condition

Plot of Hardness vs. Alloy Addition

18 20 19 21 18s 20s 19s 21s80

90

100

110

120

130

140

150

H1H2H3H4

Treatment A Mean Comparison (LSD)

Mean Comparison

Mean Difference

Less/More LSD Remark

y1-y3 -0.125 < 5.190 Not significant

y1-y6 -1.375 < 5.190 Not significant

y2-y4 -2.75 < 5.190 Not significant

y3-y6 -1.25 < 5.190 Not significant

y5-y7 -4 < 5.190 Not significant

y6-y8 -5.125 < 5.190 Not significant

Treatment B Mean Comparison (LSD)

Mean Comparison

Mean Difference

Less/More LSD Remark

y1-y2 0.3125 < 3.670 Not significant

y1-y3 12.125 > 3.670 Significantly Different

y1-y4 19.0625 > 3.670 Significantly Different

y2-y3 12.4375 > 3.670 Significantly Different

y2-y4 19.375 > 3.670 Significantly Different

y3-y4 6.9375 > 3.670 Significantly Different

DISCUSSION

Responses for Alloy Containing

Alloy Code Factors CombinationMean

Hardness%Mg %V.F Sr-ppm

18 - - - 111.75

20 + - - 124.75

19 - + - 111.875

21 + + - 127.5

18s - - + 102

20s + - + 113.125

19s - + + 106

21s + + + 118.25

Mean Value of Treatment B

H1(Temp-180,

Time-2h)

H2(Temp-180,

Time-8h)

H1(Temp-220,

Time-2h)

H1(Temp-220,

Time-8h)

977 979.5 880 824.5

CONCLUSION

•The main effect of alloy addition that is, Mg addition and volume fraction addition to alloy has increased the hardness number significantly. The contradictive is happen to Sr-modification, it cause the hardness number decrease.

•The main effect of aging time and aging temperature on the hardness is described as follow; at temperature 180oC, the main effect of aging time is not significant. At temperature 220oC, increasing the aging time will effect to hardness, which is decreasing. With the same of aging temperature, increasing temperature will decrease the hardness.

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