Carbide Terms and Glossary
Carbide and Related Terminology Glossary
Cemented Carbide
Cemented carbide is a type of sintering composite material which is composed of cementation metal compound and metal binder,At present ,the compounds used in cemented carbide are WC,Tic, TaC, NbC, Cr3C2,VC and so on ,And the binders include Co,Ni.
Main characteristics of cemented carbide are as following:(1)High hardness and strength;(2)High modulus of elasticity;(3)Stable chemical property;(4)Low impact toughness and thermal expansion coefficient.
ASTMB-311,ISO 3369
The density of material is he mass per unit volume. It’s measured per Archimedes Principle.
The content of Co in alloy is commonly determined by its density .But we can not get porosity of cemented carbide by measuring its density.
Density of EC is 15.7g
ASTMB-294,ISO 3738 & ISO 3878
One material’s hardness means the ability of counteracting diamond indenter engender impress.
Vickers-hardness (HV) is extensive used in the world now,and this hardness testing method
Means using diamond to penetrate sample surface under some burthen situation,thus to get the hardness number from testing the impress.
Rockwell hardness (HRA) is another teasting method frequently used in the world .Get the hardness by the penetrate deepness of brale.
Both HV and HRA can be used in the hardness testing of cemented carbide ,as well as they can be switched freely.
ASTMB-276,ISO 4505
Because of incompletion sinter or impurity elements will be mixed in ,micro residual porosity may exist in products’ metallurgical struture.We can use extent of porosity to measure the sizes & volume of the porosity in the cemented carbide products .Porosity influences products’ mechanical behavior.
Porosity measurements is compared with standard illustrative map when magnified about 10 times.There are two types of porosity:
A-type :less than 10μm
B-type:between 10μm~25μm
ASTMB-276,ISO 4505
During the cemented carbide products’ manufacture,owing to inadequate carton content or exorbitant oxygen content,they need consume the carbon in the cemented carbide to deoxidize , decarburization phase (η phase) will appear in the alloy structure ,this time we name it as alloy structure,this time we name it as alloy decarburization.
Decarburization will reduce the strength of the cemented carbide ,make them more fragile.
Carburization
When carbon content in alloy is higher than chemical value,free carbon or graphite phase will appear in the alloy,now it’s called as alloy carburization. Graphitic carbon is measured by “C” type porosity.
Graphitic carbon will reduce cemented carbide’s strength and wear ablity.
Grain Size of WC
About cemented carbide ,we use grain size to show its average size ,Grain size is measuredby comparing with standard illustrative map when magnified about 1500 times,WC’s grain size greatly influences products’ physical and mechanical properties. Normally, for grain size ,the thinner ,the higher strength; the thicker,the better toughness.
Per international universal classification stand,grain size of cemented carbide can be classified as following:
Magnetic Saturation
Co in the cemented carbide are magnetic,while WC,TiC, TaC and VC are nonmagnetic,For this reason,firstly we should measure Co’s magnetic saturation value in one kind of material,then compared with the corresponding value of pure cobalt sample ,and we can get alloying level of Co binder phase,because magnetic saturation is affected by alloy element.So any changes of binder phase can be measured.This method can be used to confirm the bias of ideal carbon content because carbon plays an important role during composition control.
Low magnetic saturation value indicates possibility of decarburization. High magnetic saturation indicates graphitic carbon or graphite phase may be existed.
ISO 3326
Coercive force means the residual magnetism which comes from magnetizing magnetic material
In the cemented carbide to saturation state and then demagnetization. The average particle size of the cemented carbide phase constituent is directly relevant to coercive force; The thinner
Average particle size of the cemented carbide phase constituent,the higher coe
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