Crack Paths 2006

10 -13 0-12 1 1 009876 -5

overload

cycles

(uncorrected)

Normalized 1045 (BHN203)

Long Crack ModeI,

ΔKI,eff

Long Crack ModeII,

ΔKII,eff

ΔKeq

Short Crack ModeII, [16]

As Received 1045 (BHN200)

Long Crack [15]

ΔKI,eff

Short Crack ModeI,[9]ΔKI,eff

Short Crack ModeIII, [9]

Δ K

III,eff

1

10

100

or

or

or

(MPa(m) 1/2)

ΔKI,eff

ΔKII,eff

ΔKIII,eff

ΔKeq

Figure 7. ModeI, modeII, and modeIII effective crack growth rate data for soft

S A E1045 steels combined. Long crack mode I data from[15], short

crack mode I and III data from [9], and mode II short crack data from

[16].

The convergence of the long and short crack behavior in soft steels suggests that,

once crack face interference is removed from crack growth in soft mediumcarbon steels,

a single fatigue crack growth curve may be used to describe the fatigue crack growth

behavior, for all crack growth modes or regimes (small, short, or long cracks).

C O N C L U S I O N S

1. A series crack of growth experiments were conducted on normalized SAE1045

steel, and the crack closure-free fatigue crack growth rate data were determined for

ModeI.