Effect of titanium addition on structure and properties of the as-cast high Cr–Mo white iron

Abstract

Abstract This work analyses the wear behaviour and impact toughness of high Cr –Mo white irons alloyed with titanium as related to their microstructure and solidification path. Five alloys were used with different percentages of titanium (0, 0.47, 0.932, 1.31 and 1.78 %). Such additions of titanium resulted in precipitation of small hard TiC particles in the austenitic matrix. These particles were well distributed in the matrix with Ti-additions up to 1.31% and then started to agglomerate with 1.78%Ti. Hardness increased dramatically with increasing amount of titanium addition. The wear behaviour was investigated for each alloy in the as-cast condition using the pin-on-ring configuration for 30 min against a ring made of SiC that rotated at a constant speed of 65 rpm. The wear test was performed under a load range of 30–180 N. The results are discussed in terms of microstructure and the minimum wear rate was obtained for the white cast iron alloyed with 1.31% titanium. The optimum tensile strength, impact toughness and wear resistance were also observed for the iron alloyed with 1.31% titanium. However, these properties started to deteriorate with further increase in titanium addition due to the clustering effect of titanium carbide particles in the austenitic matrix. Therefore, the optimum wear resistance and impact toughness of white cast iron under investigation (16% Cr-1.3% Mo-2.3% Ni) can be achieved by adding 1.31% titanium.