Effect of V and Sn on microstructure and mechanical properties of gray cast iron

The cylinder liner is one of the important parts of a diesel engine. Gray cast iron is the main material for manufacturing cylinder liners due to its good casting performance, convenient processing performance, good wear resistance and low cost. In the present work, the effects of vanadium (V) and tin (Sn) on the microstructure and properties of gray cast iron were studied. Results show that increasing the contents of V and Sn can not only refine the graphite, but also reduce the pearlite lamellar space. The graphite size and lamellar spacing of pearlite are firstly reduced and then increased. Pearlite quantity reaches over 98% after adding V and Sn. Adding V and Sn can promote the precipitation and solid solution strengthening of gray cast iron, so as to improve the mechanical properties. The Brinell hardness reaches the peak of 424 HB at the contents of 0.21wt.% V and 0.06wt.% Sn, and the sample containing 0.11wt.% V and 0.08wt.% Sn shows the highest compressive strength and tensile strength of 1,699 MPa and 515 MPa, respectively. The main strengthening mechanism comes from the solid solution strengthening and fine grain strengthening of V and Sn.