PSI - Issue 14

Neeta Paulose et al. / Procedia Structural Integrity 14 (2019) 649–655 Neeta Paulose etal./ Structural Integrity Procedia 00 (2018) 000–000

653

5

affected. Niobium and iron are found to be major carbide forming element in all three conditions. Niobium and iron content are similar is as cast and Cycle A. But niobium increases and iron decreases by Cycle

Table.2 Solute partitioning ratio

Elements

As cast 0.605505 1.298701 1.181403 0.802632 0.853448

Cycle A 0.567209 0.953066 1.307282

Cycle B 0.46815 0.881188 1.324232

Ni

Mn

Cr Si

1

1

Mo Nb

1.104

1.289474

0.9375

1.094595

0.75

3.3 Tensile Testing The effect of temperature on tensile property is studied at 25°C,100°C,250 °C and 550°C for all the three conditions (As cast, Cycle A and Cycle B). 0.2% Yield Strength (YS) is similar for all the three conditions at all the tested temperatures as shown in Fig.4. Decrease in YS with temperature for all the three conditions is also similar. Ultimate tensile strength (UTS) also decreases with increase in temperature for all the three conditions (Fig.5). Rate of decrease in strength (UTS) is higher up to 250°C. Beyond 250°C, UTS stabilizes and is retained till 550°C for all three conditions. Marginal variation in UTS is observed between as cast and Cycle B samples till 100°C. Beyond 100°C, as cast sample shows lower UTS compared to Cycle A and Cycle B. Till 100°C, Cycle B has lower UTS than Cycle A. But at 250°C and 550°C, UTS at both conditions is the same.

100 150 200 250 300 350 400

As cast Cycle A Cycle B

0 50

0.2% Yield Strength, MPa

0

100

200

300

400

500

600

Temperature,  C

Fig.4 Effect of temperature on 0.2% Yield Strength

0 100 200 300 400 500 600

As cast Cycle A Cycle B

UTS, MPa

0

100

200

300

400

500

600

Temperature,  C

Fig.5 Effect of temperature on ultimate tensile strength