Abrasion wear behaviour of alloyed and chilled cast irons

High-chromium white cast irons are widely used in a variety of applications that require high wear resistance. This outstanding performance is due to the presence of large amounts of chromium carbides which exhibit high hardness. However, for wear-resistant applications exposed to impact, ductile cast iron is a candidate material due to its good wear behaviour, reduced brittleness and lower production costs. That is the case of the working rolls employed in clay mass rolling operations which operate under significant wear conditions and impacts (due to foreign bodies mixed in the ceramic mass). In the present study, the effect of the chemical composition on microstructure and abrasion wear of two high-chromium white cast irons (13% Cr and 19% Cr) and a chilled ductile cast iron with 0.6% Cr was investigated. The microstructural characteristics and hardness were evaluated and correlated with the wear data. Ball cratering tests, using abrasive slurry containing SiC particles, were carried out to rank the abrasive wear resistance of the alloys, in the as-cast condition, obtained by permanent mould casting. The alloy with the highest chromium content (and higher ratio Cr/C = 6.8) presents a larger volume fraction of chromium-richer carbides providing better wear resistance. Ductile iron exhibits good wear performance in the chilled region due to a fine abrasion-resistant carbide network.

Research highlights▶ The high-chromium white cast iron (19% Cr) exhibits a high wear resistance due to the presence of large amounts of chromium-rich and hard carbides. ▶ Ductile iron exhibits good wear performance in the chilled region due to the fine abrasion-resistant carbide network formed. ▶ The abrasive wear process occurs preferentially in the metallic matrix (either austenitic or pearlitic). ▶ The ball cratering test is capable of discriminating the wear behaviour of the WCI alloys tested.