Investigation On The Influence Of Tempering On Microstructure And Wear Properties Of High Alloy Chromium Cast Iron

Mechanical properties, wear resistance and impact resistance of a high-alloy chromium cast iron used in the fabrication of grinding balls have been studied. A rank of tempering heat treatments under several temperatures 500 degrees C, 525 degrees C, 550 degrees C and 575 degrees C was performed after austenitized at 1050 degrees C. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) techniques have been used to characterize the microstructures and identify the phases. The wear balls tests were conducted in a rotating drum with a velocity 0.5 r/s. The tribological tests were carried out by evaluated a weight loss as function time. The measurement of the rebound resilience was determined by Charpy impact tests. The results of XRD showed the presence of the martensite, carbides type M7C3 and M2C for all tempering heat treated. The hardness of the sample increased after the tempering and reach nearly 65 HRC at 1050 degrees C. In another hand, it decreased after the tempering treatment it could be explained by precipitation of the carbides type M2C.