Fatigue Crack Paths 2003

C

A

B

Figure 3. Position 1, level zero. T w o magnifications. The markedrectangle in the left figure

outlines the borders of the figure to the right. Themaincrack is visible in the lower left corner close

to B andat C. A short crack through martensite is visible at the arrowin figure right. Thevisible

crack disappears in austenite. This area waschosen in order to see howthe short crack is linked

fromA to B, i.e. to the continuation of the maincrack in the lower left corner.

Figure 3 shows details of position 1 at level zero. Figure 4 shows position 1, level –

20 μm. The Ni-rich area between A and B visible in Figure 3 is almost completely

ground away is replaced by a bainitic base powder particle. A visible crack is present

from A to B.

A

A

B

B

Figure 4. Position 1, level -20µµm. Surface crack walkin twodifferent magnifications. Thebroken

line rectangle in the left figure indicates the outline of the right figure. Almostall martensite and

austenite betweenA andB is groundway andthe linking crack is visible. The linking crack is very

narrowand cannot, however, be seen in the figures reproduced here