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Norasyidah Mohd Noh , Nurlina Aimi Ramily / JOJAPS – JOURNAL ONLINE JARINGAN PENGAJIAN SENI BINA 0176269246

Figure 2 Diamond shape indentation

Figure 1 shows the indention at the recast layer 20 μm from machining surface. Figure 2 shows the indention of diamond
indent using Shimadzu Microhardness Tester. Surface of work piece must be clean and flat condition to get best indentation. The
gap distance in every indentation is 20 μm consistently. 15 values of microhardness from machining surface recorded in Table
2.

Table 2 Microhardness Value in Every Distance from Machining Surface

Distance from Voltage = 80 V, Peak Current = 32 A
machining surface Vickers microhardness value (HVN)
(μm) 12.8 μs 25 μs 50μs
20 1216 1149 1068
40 1007 1172 1013
60 989 1064 988
80 981 1045 981
100 971 985 976
120 951 973 962
140 938 969 946
160 927 946 931
180 911 941 915
200 893 919 894
220 877 900 880
240 864 884 873
260 843 872 856
280 840 854 844
300 829 843 833

From the table above, microhardness value shows high value for 12.8 μs is 1216 HVN, for 25 μs is 1149 HVN and for 50 μs
is 1068 HVN. All the microhardness highest value is at the distance 20 μm from machining surface. Graph machining surface
distance versus microhardness value are plotted as shown in Figure 3 below.

Microhardness versus Distance from
Machining Surface

1500
Microhardness Value (HVN) 500 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
1000

0

Distance from Machining Surface (μm)

25 μs
50μs
12.8 μs

Figure 3 Microhardness versus Distance from Machining Surface Graph
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