Features of Hardness and Crack Resistance Determination in Hard Alloys under Different Loading of Indenting Pyramid
Abstract
The size effect arising upon the load decrease from 50 kgf up to 0.05 kgf in measurements of the Vickers hardness for medium-grained (WC-8Co), submicron (WC-8Co-1Cr3C2) and ultrafine-grained (WC-8Co-0.4VC-0.4Cr3C2) hard alloys, as well as standard hard alloys T15K6 and VK6OM is considered. An increase in hardness resulting from the size effect attains 14 - 16%. Presence of the elevations near the penetrator indentation distorts the measurement results. The inverse dependence of hardness on the size of indentation is demonstrated. The largest dimensional effect is observed for the hardest ultrafine-grained alloy. The results of the fracture resistance measurements using Palmquist method for optical and raster microscopes are compared. It is shown that crack formation in the Palmquist scheme occurs under the impact of loads exceeding a critical value, which depends on the fracture toughness of the alloy. Annealing does not have a significant effect on the results of hardness and fracture toughness measurements. The results confirm a decrease in the crack resistance with increasing hardness due to reduction in the average grain size of WC sample when going from medium-grained hard alloys to submicron and ultrafine-grained alloys.
About the Authors
M. I. Dvornik
Институт материаловедения Хабаровского научного центра ДВО РАН
Russian Federation
Russian Federation
T. B. Ershova
Институт материаловедения Хабаровского научного центра ДВО РАН
Russian Federation
Russian Federation
E. A. Mikhailenko
Институт материаловедения Хабаровского научного центра ДВО РАН
Russian Federation
Russian Federation
V. O. Krutikova
Институт тектоники и геофизики ДВО РАН
Russian Federation
Russian Federation
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Review
For citations:
Dvornik M.I., Ershova T.B., Mikhailenko E.A., Krutikova V.O. Features of Hardness and Crack Resistance Determination in Hard Alloys under Different Loading of Indenting Pyramid. Industrial laboratory. Diagnostics of materials. 2017;83(9):57-65. (In Russ.)
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