Tungsten carbide quality control
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Update time : 2017-12-11 15:45:17
Free carbon/graphite
ISO4505
Carbon that is higher than the stoichiometric value brings about the formation of free carbon,i.e.the non-combined carbide in materials.the optimal carbon content in WC is 6.128wt%.the acceptable range of carbon content is 6.05-6.14%.any surplus amount higher than 6.14% will bring about the formation of free carbon,i.e.the graphite in the microstructure.the evaluation of the volume of graphite in cemented carbide follows the same procedure as porosity.the presence of graphite will considerably reduce the strength and wear resistance of materials.
η phase
ISO4505
Carbon lower than the stoichiometric value will bring about the formation of η phase carbides.the optimal carbon content in WC is 6.128wt%.the acceptable range of carbon content is 6.05-6.14#.carbon lower than 6.02% will resut in visible deficient carbon and the formation of ηphase carbides.
The evaluation of the volume of graphite in cemented carbide follows a similar procesure as for porosity.
The presence of these carbide phases will substantially reduce the strength of the materials and increase their brittleness.
Transverse rupture strength
ISO3327
Transverse rupture strength is the stress measured at the ruptured point of a material in a bending test at 3 standard points.when the test is applied to cemented carbide,a standard loaded fixture and a sample ot(3.25x38mm)is used.the average of several measured values is taken as the measured value.the value can vary much with the geometry and surface status of the sample and testing equipment.what is to be especially pointed out is that the test is sensitive to the surface finish,residual surface stress,surface corrosion and the internal defects of the material.
It should be noted that TRS can not be take as the only standard for the selection of a carbode grade.
ISO4505
Carbon that is higher than the stoichiometric value brings about the formation of free carbon,i.e.the non-combined carbide in materials.the optimal carbon content in WC is 6.128wt%.the acceptable range of carbon content is 6.05-6.14%.any surplus amount higher than 6.14% will bring about the formation of free carbon,i.e.the graphite in the microstructure.the evaluation of the volume of graphite in cemented carbide follows the same procedure as porosity.the presence of graphite will considerably reduce the strength and wear resistance of materials.
η phase
ISO4505
Carbon lower than the stoichiometric value will bring about the formation of η phase carbides.the optimal carbon content in WC is 6.128wt%.the acceptable range of carbon content is 6.05-6.14#.carbon lower than 6.02% will resut in visible deficient carbon and the formation of ηphase carbides.
The evaluation of the volume of graphite in cemented carbide follows a similar procesure as for porosity.
The presence of these carbide phases will substantially reduce the strength of the materials and increase their brittleness.
Transverse rupture strength
ISO3327
Transverse rupture strength is the stress measured at the ruptured point of a material in a bending test at 3 standard points.when the test is applied to cemented carbide,a standard loaded fixture and a sample ot(3.25x38mm)is used.the average of several measured values is taken as the measured value.the value can vary much with the geometry and surface status of the sample and testing equipment.what is to be especially pointed out is that the test is sensitive to the surface finish,residual surface stress,surface corrosion and the internal defects of the material.
It should be noted that TRS can not be take as the only standard for the selection of a carbode grade.