Effect of the simultaneous Ti and W addition on the microstructure and wear behavior of a high chromium white cast iron

摘要

The present work analyzes the effect of 0.7%Ti and 1.7%W addition to a 17% chromium white iron in as-cast condition and after destabilization heat treatment. These alloys are commonly used in applications where a high abrasive wear resistance is required. For this reason, in addition to the characterization, a complementary wear test was performed. The alloys were characterized by optical and electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The simultaneous Ti and W addition promoted the (Ti, W)C primary carbides formation which grow in the early stages of solidification. These carbides were found well distributed in the iron matrix with an average hardness value of 2450 HV. Moreover, tungsten was found partially distributed in the different phases increasing the microhardness by solid solution and refining the eutectic carbide. These microstructural modifications resulted in the increase of the bulk hardness and abrasive wear resistance of the alloyed iron. After destabilization heat treatment, the carbide precipitation and the matrix transformation produced a secondary hardening reducing the wear losses. Based in the results of the present study, the simultaneous addition of these elements to promote the (Ti,W)C carbide formation during solidification represents an effective method to increase the hardness and wear resistance of these kind of alloys via small additions.