Effect of Corrosion-Induced Damage on Microstructure and Residual Strength of Wc-Co,Ni Cemented Carbides

摘要

In this work the corrosion behavior of cemented carbides with two different binders, Co and Ni, andcarbide mean grain size, ultrafine and coarse, was studied. Immersion tests in acidic, neutral andalkaline solution were performed to induce corrosion damage in a controlled way and to determinecorrosion rates. Electrochemical parameters were measured together with a microstructuralcharacterization of the corroded surfaces. The influence of microstructure on the tolerance tocorrosion damage was carried out by using residual strength as the critical parameter. Resultsrevealed that corrosion rates were lower in alkaline solution. In contrast, acidic solution led to a highercorrosion rates especially for cemented carbides with Co regardless the influence of carbide meangrain size. Corrosion damage resulted in strength degradation due to the formation of surfacecorrosion pits in acidic solution. In neutral and alkaline solutions, higher strength losses weredetermined for the ultrafine grade.