Effect of casting pressure on microstructural evolution and wear behavior of Fe–Cr–C white cast iron

The mechanical properties of hypoeutectic Fe–Cr–C cast iron are mainly determined by the type, quantity and distribution of eutectic carbide and microstructure of matrix. Low chromium hypoeutectic cast iron was cast under three different conditions involving atmospheric pressure, 100 and 170 MPa. By SEM, XRD analysis, the pressure of 100 MPa reduced the grain size. The smooth solid-liquid interface produced by the solidification of chromium carbide is transformed into the rough interface as austenite, and the carbide grows on a non-small crystal plane and becomes a regular eutectic with austenite. In addition, the pressure reduces the Cr segregation, and the carbides are partially transformed into M7C3 with higher hardness. The impact wear properties of the alloy are improved by 1.5 times compared with gravity casting due to the microstructures obtained under the pressure of 100 MPa. But when the pressure is increased to 170 MPa, the carbides increase and coarsen, which weakens their wear properties.