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Fe-17Cr-4C-2V-Mn-Si-Ti complex system hardfacing alloys were deposited by using flux-cored wire self-shielded open arc welding. The effects of silicon on their <i>M</i>₇C₃ (<i> M</i> =Fe, Cr, V, Mn) phases and abrasion resistance were investigated by OM, XRD and SEM. The results show that, with silicon content increasing from 0.6%(mass fraction) to 2.4%, the size of primary <i>M</i>₇C₃carbides gradually reduces and transites from rod-like shape to block-like shape in dispersion distributing state. γ-Fe phases, which adjacent to those primary <i>M</i>₇C₃ grains, progressively reduce until disappear. It dues to that silicon can change the precursor of primary <i>M</i>₇C₃ nucleates in nature, <i> e.g.</i> liquid high carbon atom clusters and it results in the change of their morphology, distribution and size. The wear test results indicate that the abrasion resistance of open arc hardfacing alloys improves firstly and then reduces when silicon content increases from 0.6% to 2.4%. The optimum abrasion resistance is acquired at 1.5%Si. The analysis on the surface worn morphologies show that the micro-cutting and micro-spalling wearing mechanisms coexist.