Effect of Heat Treatment on Structure and Wear Resistance of High Chromium Cast Steel Containing Boron

The microstructure, mechanical properties and wear resistance of high chromium cast steel containing boron after different heat treatments were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness, impact toughness, tensile and pin-on-disc abrasion tests. The results show that as-cast microstructures of boron-free high chromium steel consist of martensite and a few (Cr, Fe)7C3 carbide, and the macro-hardness of boron-free high chromium steel is 55–57 HRC. After 0.5 mass% B was added into high chromium cast steel, as-cast structure transforms into eutectic (Fe, Cr)2B, (Cr, Fe)7 (C, B)3 and martensite, and the macro-hardness reaches 58–60 HRC. High temperature quenching leads to the disconnection and isolated distribution of boride, and there are many (Cr, Fe)23 (C, B)6 precipitated phases in the quenching structure. Quenching from 1050 °C, high chromium steel obtained the highest hardness, and the hardness of high chromium cast steel containing boron is higher than that of boron-free high chromium steel. The change of quenching temperature has no obvious effect on impact toughness of high chromium steel, and the increase of quenching temperature leads to tensile strength having an increasing tendency. At the same quenching temperature, the wear resistance of high chromium cast steel containing boron is more excellent than that of boron-free high chromium steel. High chromium cast steel guide containing boron has good performance while using in steel bar mill.