PSI - Issue 2_A

Nobuo Nagashima et al. / Procedia Structural Integrity 2 (2016) 1435–1442 Author name / Structural Integrity Procedia 00 (2016) 000–000

1437 3

Table1 Low-cycle test results.

Fatigue damage value, D

pseudoelastic strain amplitude, ε PEa

Number of cycles to failure, N f (cycles)

Stress amplitude, σ a (MPa)

Plastic strain amplitude, ε pa

Elastic strain amplitude, ε ea

Total strain amplitude, ε ta

- - -

0.0043 0.0034 0.0025 0.0018 0.0060 0.0058 0.0049 0.0046

0.0157 0.0106 0.0065 0.0042 0.0140 0.0082 0.0041 0.0016

0.020 0.014 0.009 0.006 0.020 0.014 0.009 0.006

607 524 413 317 722 711 679 618

164 304

1.25 0.83 1.21 1.25 0.81 0.99 1.11 0.76

SUS 304 Steel

1600 5250

-

157 631 3315 18290

0.0020 0.0018 0.0013 0.0008

FMS alloy

800

10 1 Stress amplitude, σ a (MPa) 0 200 400 600

FMS alloy SUS304 steel

10 2

10 3

10 4

10 5

Number of cyclics to failure, N f (cycles)

Fig. 2: S-N diagram showing the low-cycle fatigue properties, ○ mark SUS304 steel, ● mark FMS alloy.

500

(a) SUS304

(b) FMS alloy

500

E = 193GPa

2.0%

E = 193GPa

2.0%

1.4%

1.4%

Stress, σ a , (MPa)

0

0

0.9% 0.6%

0.9% 0.6%

ε pa

PE

ε r

Stress (MPa)

-500

ε PEa

-0.03 -0.02 -0.01 0 0.01 0.02 0.03 -500

-0.03 -0.02 -0.01 0 0.01 0.02 0.03

Strain, ε

Strain

Fig. 3. Stress-strain hysteresis loops at half-life cycle N f/2 showing (a) SUS304 steel, and (b) FMS alloy. Each four loops obtained of total strain amplitude: 2.0%, 1.4%, 0.9% and 0.6%. 3. Experimental Results and Discussion Figure 2 shows the relationship between the number of cycles to failure ( N f), and the stress amplitude ( σ a = Δσ /2). Table 1 shows the results of the low cycle fatigue test. At very high stress amplitudes, the FMS alloy had a cyclic life to failure longer than SUS304 steel. This is in agreement with the characteristics of high manganese steel observed by Nishida et al. Figure 3 shows the stress-strain hysteresis loops at N f/2, for all specimens, in the low cycle fatigue test. In the test, the intersection of the unloading curve at zero stress represented cyclic plastic strain ( ε pa = Δε p /2). The gradient of