Meaning
Vickers hardness testing under a thirty-kilogram force load measures localized plastic deformation resistance in dense metallic and ceramic compounds. Standardized force application during this test determines micro hardness HV30, which evaluates the mechanical wear resistance of cemented carbide slitting tools. Micro hardness HV30 governs structural quality verification for hard metal components where grain size and cobalt binder content determine surface durability.
The measurement provides a comparative metric across tool grades, reflecting the composite resistance of tungsten carbide grains within the metallic matrix. Operational boundaries stop at highly heterogeneous or thin coatings where light test loads under one kilogram force are required to isolate individual phase properties.
Indentation Physics
A square-based diamond pyramid indenter applies a controlled force of 294.2 Newtons into the polished hard metal specimen surface for a dwell time between ten and fifteen seconds. Optical microscopy measures the diagonal lengths of the resulting square indentation to calculate the contact stress area. The calculated ratio of test force to surface area yields the hardness value in Vickers units.
Surface preparation requires diamond polishing to eliminate work-hardening artifacts from sectioning.
Grade Differentiation
Sub-micron tungsten carbide grades exhibit higher indentation values due to reduced mean free path between hard carbide grains.
Wear Prediction
Tooling performance during continuous foil slitting correlates with measured hardness values across production batches. Higher micro hardness HV30 values indicate increased resistance to abrasive wear caused by hard ceramic slurry particles on electrode surfaces. Excessively high hardness readings warn of low fracture toughness, which increases vulnerability to micro-chipping during high-impact cutting operations.
Blade manufacturers balance hardness against transverse rupture strength to maintain cutting edge integrity over extended production runs. Hardness testing protocols require multiple indentations across blade cross-sections to detect local soft spots resulting from binder pooling or cobalt migration. Quality control specifications reject cutting knives whose measured values fall outside defined tolerance bands.
