Mechanical behavior and microstructure of hypereutectic high chromium cast iron: the combined effects of tungsten, manganese and molybdenum additions

Abstract

The combined effects of W, Mn and Mo additions on the microstructure and properties of a hypereutectic high chromium cast iron (HCCI) were studied. The results indicated that W was distributed uniformly in the matrix and carbides. The W and Mo addition promoted the formation of M2C and M6C carbides. When 13 wt.% Mn was added to the samples, the solubility of Mn in the matrix increased the stability of the austenite phase and improved the toughness of the materials. Moreover, Mn and Cr form the M7C3 carbides in hypereutectic HCCI. A large number of (Fe, Mn)3C carbides were produced in the matrix during the later stage of solidification, which significantly improved the wear resistance of the matrix. When the amount of W, Mn and Mo added was 6 wt.%, 15 wt.% and 4.2 wt.%, respectively, the HCCI exhibited the best performance herein. The addition of 6 wt.% W led to an increase in the average hardness of the samples and the microhardness of carbides of up to 57.5 HRC and 1680 HV, respectively. Similarly, it is worth mentioning that the impact toughness of the 6% W sample reached 6.35 J/cm2, and the mass loss of the Cr16 and 0% W samples was 1.43 and 1.23 times that of the 6% W sample, respectively. The wear resistance of the 6% W sample showed no significant change before and after heat treatment. The combination of W, Mn and Mo simultaneously improved the wear resistance and impact toughness of the hypereutectic HCCI.

Keywords

• Microstructure
• Eutectic cementite
• Wear
• Hypereutectic high chromium cast iron
• Tungsten
• Manganese and molybdenum additions