Microstructure and Properties of Casting Fe-Cr-B Alloy After Quenching Treatment

The as-cast microstructure of Fe-4Cr-B alloy has been systematically investigated, which contains 1 wt%B, 4 wt%Cr, 0.35 wt%C, 0.8 wt%Si and 0.8 wt%Mn. The investigation was carried out by optical microscopy (OM), scanning electron microscopy (EDS/SEM), X-ray diffraction (XRD), hardness tester and wear tester, and the quenching temperature effect on its microstructure and mechanical property was studied. The results showed that ferrite, pearlite, martensite and borocarbides were the main composition of the solidification microstructure of casting Fe-4Cr-B alloy. After water quenching at 950-1150 degrees C, the matrix transformed to martensite, and the secondary borocarbides M-23 (C, B)(6) precipitated from the matrix, and then the continuous distribution of M-2 (B, C) (M = Fe, Cr, Mn) among dendrites began to break. As the water quenching temperature increased, the phenomenon of disconnection became more clearly. When the water quenching temperature was 1100 degrees C, the network borocarbides fractured and formed an isolated distribution. The hardness of the alloy increased first and then decreased. At water quenching temperature of 1100 degrees C, the hardness reached the maximum of 62.8 HRC. The abrasive resistance and hardness of casting Fe-4Cr-B alloy changed at the same trend.