PSI - Issue 19

Masaru Bodai et al. / Procedia Structural Integrity 19 (2019) 64–72 Bodai,M et al. / Procedia Engineering 00 (2019) 000 – 000

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other paper (Bodai et al., 2019) discussed fatigue crack growth of the large-scale fatigue piping tests using austenitic stainless steel piping. In this paper, crack growth analysis is carried out for the beach marks introduced during the large-scale fatigue piping tests and the analysis results are compared with the crack depths obtained from the beach marks.

2. Observation of crack initiation and growth used from large-scale piping tests

2.1 Material A series of large - scale piping tests using austenitic stainless steel piping was performed ( Bodai et al ., 2018). Austenitic stainless steel piping of JIS SUS316LTP (equivalent to SA - 312 TP316L) NPS 8 and Schedule 160 was used. The chemical compositions and the tensile properties are shown in Table 1 and Table 2 respectively from the certified material test report of the piping. Here, the specification of tensile strength for SUS316TP is shown in Table 2 as a reference and this material satisfies the tensile requirements of SUS316TP.

Table 1. Chemical compositions. SUS316L C

Si

Mn ≤ 2.00 1.79

P

S

Cr

Ni

Mo

≤ 0.030 0.012

≤ 1.00 0.44

≤ 0.045 0.025

≤ 0.030 0.001

16.00 18.00 17.35

12.00 16.00 14.56

2.00- 3.00 2.61

Req.

Heat

Table 2. Tensile properties. SUS316L

Yield Strength (MPa)

Tensile Strength (MPa)

Elongation (%)

≥ 175 ( ≥ 205 )

≥ 480 ( ≥ 520 )

≥ 30 ( ≥ 30 )

Req. of 316L ( Req. of 316 ) Room Temp.

238

542

60

A small notch was applied to the tested pipes to limit the portion of fatigue crack initiation as shown in Fig. 1. Here, the radius of the notch was determined by elastic Finite Element analysis used ABAQUS 6.8 - 4 and the stress concentration factors of 1.39 at point A and 1.14 at point B were obtained.

Notched Portion

ϕ 170.3

ϕ 216.3 ϕ 216.3

≈3 ,000

Point B (Edge)

X

≈50.6

Point A (Center)

≈40.5

(Units) mm

3

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Fig. 1. Pipes for tests.