PSI - Issue 2_B

6

Girolamo Costanza et al. / Procedia Structural Integrity 2 (2016) 3508–3514 Author name / Structural Integrity Procedia 00 (2016) 000–000

3513

When penetration rate does not exceed 0.1 mm/min, FIMEC test gives good indications about mechanical behavior of materials during tensile test with deformation rate of 10 -3 s -1 . In these conditions the following relationship has been experimented to estimate the yield strength σ y through the pressure p y : σ y ≈ p y /3 (1) The p y /3 values, obtained by FIMEC test performed on base materials and welded zones of the various samples, are given in table 3.

Table 3 - Results of FIMEC test. Sample No

Sample material

Test zone

p y /3 (MPa)

AISI 304 AISI 316 AISI 304 AISI 316 AISI 304 AISI 304 AISI 304 AISI 304 AISI 316 AISI 304

BM BM WZ WZ WZ WZ WZ WZ WZ WZ

339 339 280 290 310 310 278 289 275 279

1 2 3 4 5 6 7 8

Table 4 - Results of tensile test: yield stress and joint efficiency. Sample No Sample material σ y (MPa)

Fracture zone

Joint efficiency (%)

AISI 304 (parent metal) AISI 316 (parent metal)

335 312 280 290 300 310 270 270 275 288

1 2 3 4 5 6 7 8

AISI 304 AISI 316 AISI 304 AISI 304 AISI 304 AISI 304 AISI 316 AISI 304

WZ WZ WZ WZ WZ WZ WZ WZ

83 93 89 92 80 80 88 86

Table 5 - Results of tensile test: ultimate stress and joint efficiency. Sample No Sample material σ u (MPa)

Fracture zone

Joint efficiency (%)

AISI 304 (parent metal) AISI 316 (parent metal)

714 625 606 569 594 618 578 616 571 589

1 2 3 4 5 6 7 8

AISI 304 AISI 316 AISI 304 AISI 304 AISI 304 AISI 304 AISI 316 AISI 304

WZ WZ WZ WZ WZ WZ WZ WZ

85 91 83 87 81 86 91 83

During tensile test all the samples have shown plastic behavior with large deformations and final fracture localized in the WZ. Moreover it is worth to notice that the yield stress of each sample is very close to the p y /3 value obtained by FIMEC test. Yield and ultimate stress data are given respectively in table 4 and 5, together with the joint