EFFECT OF CARBIDE ORIENTATION ON ABRASION OF HIGH CR WHITE CAST-IRON

Wear resistant, high chromium white cast irons contain high volume fractions of M(7)C(3) type carbides, which grow as rods and blades during solidification to produce a highly anisotropic microstructure. In this study, the effect of carbide orientation on the wear properties of these alloys is examined using both a high-stress pin-on-drum abrasion test and a single scratch test. It is found that when the carbides are oriented with their long axes perpendicular to the wear surface, abrasion resistance is considerably reduced. When the long axes of the carbides are parallel to the wear surface, the cast irons are more wear resistant, and the alloys show the least wear when the long axes of the carbides are parallel to the wear surface and oriented perpendicular to the wear direction. Scanning electron microscopy reveals that fracture of the carbides depends upon the orientation of the carbides with respect to the wear surface and the wear direction.