Basic HTML Version
Table-1 Hardness of Alloy Carbides
(Source: Crucible service center)
Iron Carbides are formed during Heat Treatment of steel. During Heat
Treatment there is a phase transformation. This Phase
Transformation results in a hard structure called Martensite or Bainite.
There are some alloying elements like Chromium, Nickel etc which
retard the transformation and these elements are called as Austenite
Stabilizers. Regions of this form the sites of initiation of the abrasive
wear. To reduce or to eliminate this retained Austenite, the steels are
subjected to Cryogenic Treatment.
Fig. 1 Microstructure of SISI M62 and Wr5
Alloy Carbide
(-)
Chromium Carbide
Molybdenum Carbide
Tungsten Carbide
Vanadium Carbide
Hardness
(HRC)
66-68
72-77
72-77
82-84
WR5 (Wt. %)
1.8
5
1.4
9
Table-2 Materials considered for experiment
-: An Experiment :-
WR5 and AISI M62 with chemistries as shown in table-3 are considered. The wear test samples of both steels were subjected to hardening
and tempering. The achieved hardness of WR5 and AISI M62 were 61 and 63 RC respectively. The microstructure photos of both the steels
were captured using Light reflected microscopy as shown in fig.1. The Abrasive wear resistance of the material was evaluated using Dry
Abrasion Tester as per ASTM G 65 standard practice as shown in fig.2. The load applied and the speed were identical during the test for both
considered tool steels.
As shown in fig.3, the mass loss recorded in AISI M62 was more compared to WR5. This shows that abrasive wear resistance of WR5 is more
than that of AISI M62. Though the hardness was comparable, the alloy carbides made the difference in the mass loss. From these it is evident
that hardness of steel only cannot be the index of Abrasive wear resistance of the material.