PSI - Issue 60

B Shashank Dutt et al. / Procedia Structural Integrity 60 (2024) 471–483 Author name / StructuralIntegrity Procedia 00 (2019) 000 – 000

478

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fracture toughness values varied in the range of 5-17 %, compared to determined fracture toughness values. Determined fracture toughness values ( J 1.0 and J 2.0 ) in previous study corresponded to crack extensions of 1.0 and 2.0 mm. From the previous studies (Youn et al. 2021), it is observed that estimated (conservative) fracture toughness was greater than 40% of determined J 0.2 for RT tested GTAW welds. It is also to be noted that a one to one comparison (advantages and limitations) of previous (Youn et al. 2021; Kim et al. 2022) models is difficult, considering that previous estimation methods were not applied in this study. In a previous study (Hahn and Rosenfield 1968) for various titanium alloys and steels, variation of ± 30% in estimation of K 1c was observed. From the previous (Youn et al. 2021; Hahn and Rosenfield 1968) studies, it can be inferred that variation of ± 30% in estimated K 1c values (compared to determined fracture toughness values) is acceptable for welds. In this investigation, it is summarized that the previous estimation (Baskes 1975) method is applicable for austenitic stainless steel welds.

Table 3: Estimated K 1c results of SS 316 LN welds tested at RT

Aging temperature (°C) and durations (h)

Estimated Modulus of toughness MJ.m -3

Estimated K 1c ( MPa. m 0.5 )

Determined K j1c ( MPa. m 0.5 )

Percentage difference (%)

As welded

173

275

278

1

Aged at 370, 1000 h Aged at 370, 10,000 h Aged at 370, 20,000 h Aged at 475, 1000 h Aged at 475, 10,000 h

156

262

278

5

178

280

267

4

166

270

257

5

97

206

297

30

68

173

274

36

Aged at 475, 20,000 h

78

186

236

21

Aged at 550, 1000 h

84

192

291

34

Aged at 550, 10,000 h

91

200

255

21

Aged at 550, 20,000 h

84

193

231

16