STUDY ON THE BREAKDOWN OF MILLING BALLS MADE OF 13%Cr WHITE CAST-IRON WORKING IN STRONG ABRASIVE AND CLASH CONDITIONS

Abstract

The breakdown due to abrasion and clash of the milling balls made of 13% Cr white cast iron is a complicated process which depends on many factors, especially on the strength of the matrix and carbide phases. As shown, stresses created by abrasion and clash processes are concentrated mainly at the locations such as carbide/matrix boundary and around coarse carbide particles, leading to the cracks and breakdown there. The peeling off carbide particles can be a reason of scratches on the specimen surface. Heat treatment (quenching in oil and tempering at 2500 C for three hours) to transform a soft matrix (austenite) to a harder one (martensite) can be a good solution against abrasion. Concerning the impact, the solution should be the refinement of the carbide particles and their uniform distribution.

Keywords

• chromium white cast iron
• milling balls