PSI - Issue 14

Amit Singh et al. / Procedia Structural Integrity 14 (2019) 78–88 Amit Singh et al./ Structural Integrity Procedia 00 (2018) 000 – 000

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Table 4. Strength coefficient and strain hardening exponent values from the R 2 ~1 values

Flow stress model Samples [ST + Aged (973/2hrs)]

Hollomon

Swift

Ludwigson

ε o

n

K

n 2

K 2

n 3

K 3

n 4

K 4

ST (1288 K) ST (1303 K) ST (1318 K) ST (1333 K)

0.0516 0.0481 0.0463 0.0391

1033.884 1288.141 1187.173 1084.774

0.044 0.055 0.048 0.027

1012.430 1251.689 1195.061 1036.638

-0.0013 0.0029

0.1072 0.0435 0.0420 0.0109

1186.846 1198.042 1169.260 1304.614

4.905

-34.913 -0.632 -2.002

46.558 68.899 -45.987

0.007

-0.0018

5.263

Table 5. Stages of strain hardening, strain hardening exponent and modified C-J model parameter

ST + aged (973 K/2Hrs)

Stages of strain hardening

(1-m)

ln C

Stage I Stage II Stage III Stage I Stage II Stage III Stage I Stage II Stage III Stage I Stage II Stage III

-19.5845 -8.8327 -118.8220 -27.9407 -3.5101 -84.2637 -27.4065 -3.27018 -103.3670 -30.5059 -22.9595 -131.1007

142.7431 66.3434 1079.5475 201.0554 31.60948 596.85975 196.54206 29.8444 727.2963 215.9673 164.5837 90.6878

0.0475 0.10 0.0062 0.0352 0.22 0.0117 0.0345 0.234 0.0095 0.031 0.041 0.0073

ST (1288 K)

ST (1303 K)

ST (1318 K)

ST (1333 K)

Fig. 5 TEM images of IMI 834 alloy, (a) Ti 3 Al (α 2 aluminide phase) p recipitates inside the α phase and (b) (Ti, Zr) 6 Si 3 (S 2 silicide phase) at the boundary of lamellae, Lutjering and Williams (2007).