Prakt. Met. Sonderband 52 (2018) 257
TO sq,
rns) Table 1 — Analysed alloys and their carbides I
— Nominal chemical composition in wt.-% Carbide Carbide Carbide
or RIE ome dW Co NG phases ful Gong
Alloy #1 High speed steel 2.3 4 / 65 65 105 - 2 MC MC
Alloy #2 Cold work steel 25 4 4 9 1 2 . 1 MC -
Alloy#3 ~~ Cold work steel 2.3 13 1.1 4 : - - 2 MC M,C;
3.2. Equipment and methods
Scratch tests were conducted with a scratch tester (CSM instruments; NST module)
equipped with a diamond wedge-shaped indenter (apex angle 26 = 115°, attack angle a =
90°). The penetration load was selected of 5 mN, the total length (s) was 3.5 mm and the
scratch speed of 400 um/min. The low load was deliberately selected to produce a groove
size D, of approximately the carbide size d, and thus being able to observe the effect each
View, b) Fy phase has on the overall groove size.
Sin um The deformation induced by the scratch tester was investigated by means of confocal laser
; scanning microscopy (CLSM). The device employed was a Keyence VK-X160 (red laser
diode, wavelength of 658 nm), operated with a 1500x objective lens.
Cain ang te
ngs a.
2mm; 4. Results
Table 2 show the main results yielded by the image analysis and CLSM examination, and
Figure 3 shows the depth profile of the Alloy #1 superimposed upon a micrograph taken with
; confocal microscopy. All alloys displayed a reduction of scratch depth and width as their
hard phases contacted the indenter, with transitions of effective attack angles smaller than
the indenter original attack angle.
ntial function,
{ne result, vg Table 2 — Image analysis and CLSM examination results ]
Alloy A Ay hy hap fa d v a Vo.
a. um? um’ um um pm um % ° pm?
Alloy #1 0.018 0 0.047 0 0371 - 3.92 0.90 19.08 325 0.0051
Alloy #2 0.030 0.004 -0.068 -0.01 0.244 0.854 3.00 0.73 21.04 433 0.0060
Alloy #3 0.025 0.006 -0.057 -0.01 0201 0819 3.24 0.92 24.50 3.17 0.0048
sented in ff) - -
alue a = 90°
5. Discussion
The low load single-scratch tests provided a particularly favourable framework to analyse
” the individual-phase and compound properties of the selected tool steels. The different
58 tae alloys attained different maximal and minimal groove depths (and therefore widths). The
¢ nfoducl reason for this behaviour is mostly attributed to the different matrix hardness.
ve PM tees With Equations (2) and (5) the effect of the microstructure can be easily analysed, provided
there is no micro-cracking in the hard phases.
The collected information on the size distribution and shape of the carbide phases is of
content, and particular interest in the field of microstructure characterization and reconstruction, being the
ie te raf next logical step in the ongoing research to build artificial 3D microstructures to seek to fully
ong We understand and optimize the overall abrasive wear resistance of this kind of material.
