PSI - Issue 19

Motoki Nakane et al. / Procedia Structural Integrity 19 (2019) 284–293 Author name / Structural Integrity Procedia 00 (2019) 000–000

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results obtained here calls attention that surface finish by multiple grinding work at same place, same direction which perpendicular to the cyclic loading should be avoided.

Fig. 11 Cross sectional and birds eye view of fatigue crack (  ta =0.2%).

Fig. 10 Macroscopic photo of grinding finished surface.

Loading direction

Grinding scratch

Fracture surface

(a)  ta =0.115%

(b)  ta =0.2%

Fig. 12 Fracture surface observation of Type 2 grinding finished fatigue test specimens.

0 10 20 30 40 50 60 70

0 10 20 30 40 50 60 70

■ Grinding (Type 2) ■ Grinding (Type 3)

■ Grinding (Type 2) ■ Grinding (Type 3)

Grinding (Type 2 ,  ta =0.115%)

Grinding (Type 2 ,  ta =0.115%)

Number

Number

2.0 ≦ a<4.0

4.0 ≦ a<6.0

6.0 ≦ a<8.0

a<2.0

10.0 ≦ a<12.0

12.0 ≦ a<14.0

14.0 ≦ a<16.0

16.0 ≦ a<18.0

8.0 ≦ a<10.0

0.1 ≦ a/w<0.2

0.2 ≦ a/w<0.3

0.3 ≦ a/w<0.4

0.4 ≦ a/w<0.5

0.5 ≦ a/w<0.6

0.6 ≦ a/w<0.7

0.7 ≦ a/w<0.8

0.8 ≦ a/w<0.9

0.9 ≦ a/w<1.0

1.0 ≦ a/w<1.1

1.1 ≦ a/w<1.2

1.2 ≦ a/w<1.3

1.3 ≦ a/w<1.4

a/w<0.1

(a) Scratch depth a

(b) Scratch depth a / width w

Fig. 13 Typical view of groove-like scratch.

Fig. 14 Grinding scratch and groove-like scratch observation results.