PSI - Issue 7

Hiroshige Masuo et al. / Procedia Structural Integrity 7 (2017) 19–26 Hiroshige Masuo et Al./ Structural Integrity Procedia 00 (2017) 000–000

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Table 3 Summary of fatigue data and other properties

Approximate Fatigue limit (MPa)

Surface roughness Ra ( μ m) Rz ( μ m) 32 ～ 42 219 ～ 290 30 ～ 41 212 ～ 254

Process

Surface condition HIP

HV

No Yes No Yes No Yes No Yes No Yes

140 195

369 345 369 345 378 340 378 340 310 300

As built

EBM

240 ～ 260

Surface polish

－

590 155

AM

10 ～ 13 12 ～ 13

75 ～ 90 86 ～ 96

As built

195 ～ 220

DMLS

370 610

Surface polish

－

530 ～ 540

Rolled material

Surface polish

－

440

(a)

(b) High magnification of (a)

(a)

(b) High magnification of (a)

Fig. 5 Surface morphology for EBM specimens

Fig. 6 Surface morphology for DMLS specimens

(a)

Fig. 7 Defects observed on the section of as-built EBM specimen without HIP

Fig. 9 Fatigue fracture origins of surface polished EBM specimens without HIP and estimation of the effective defect size.

(b)

Fig. 8 Disappearance of defects from the section of as-built EBM specimen with HIP

(a)

(b)

Fig. 10 Fatigue fracture origins of surface polished DMLS specimens without HIP and estimation of the effective defect size.

Table 3 summarizes all the experimental results and the basic material properties. The fatigue limits cited in Table 3 are the values determined approximately from S - N data of Fig. 3 and Fig. 4. Since individual specimens contain defects having different size and shapes, we cannot determine the exact fatigue limit for individual specimens prior to