Four Main Carbide Grades Groups Introduction
1) WC-Co Grades:
This group contains WC and Co only(i.e two-phases) and few trace elements. These grades are classified according to their cobalt content and WC grain size.
The grades with binder content in the range 10%~20% by weight, and WC grain size between 1um and 5um have high strength and toughness, combined with good wear-resistance.
The grade with binder content in the range 3~15% and WC grain size below 1um have high hardness and compressive strength, combined with exceptionally high wear-resistance.
The gmond-hardmetal grade programme also includes WC-Co grades which utilize a range of ultra-fine WC grain size(<0.5um).With such fine, uniform grain sizes, a unique combination of hardness, wear-resistance and toughness can be achieved.
2) Corrosion resistant grades.
This group contains cemented carbide grades in which the binder phase has been specifically designed to improve corrosion resistance above those grades which contain cobalt alone.
This is achieved by alloy the cobalt binder phase with element such as nickel and chromium or completely replacing it by more corrosion resistant alloy.
3) Dual property(DP) grades
This group contains grades which have had the distribution of their binder phase modified in such a way to create a material with different properties in the surface zone compared with the bulk.
This is new concept developed by Gmond-Hardmetal,enables components to be produced which contain distinct microstructural zones, each with a different binder content. Thus each zone has different properties,--hence the term” dual property”.
4) Grades containing cubic carbides
This group consists of grades containing a significant proportion ofγ-phase(Ti,Ta,Nb)C together with WC and Co(ie…three phase materials)
Main feathers ofγ-phase are thermal stability, low grain growth, and resistant to oxidation.
These grades have been designed to provide a good balance of wear resistance and toughness in applications in which there is intimate contact with ferrous materials and in which a high temperature is generated.Typically,these conditions arise in metal cutting or high pressure sliding contact situations where welding and galling of the surfaces are encountered.
