REPEATED IMPACT ABRASION TESTING OF ALLOY WHITE CAST IRONS

A small Hazemag rotary impact crusher has been adapted for the assessm ent of the repeated impact-abrasion properties of alloy white cast iro ns. The test specimens were cast as blow bars for use in the crusher, and each test involved the comminution of 2000 kg of quarry stone. A s eries of six alloy white cast irons has been tested in the crusher in order to assess the influences of chemical composition, hardness, eute ctic carbide volume fraction and retained austenite content on combine d repeated impact-abrasion performance. The results showed that harden ing by heat treatment, and hence variations in retained austenite cont ent, had no influence on weight loss, but that weight loss increased s ignificantly with increasing eutectic carbide volume fraction. Post-we ar examination of worn blow bars revealed significant gouging and impa ct damage on the surface, and on a finer scale, extensive fracture of eutectic carbides, decohesion at carbide/matrix interfaces, matrix fra cture, and microscopic spall formation.