EVALUATION OF THE ABRASIVE WEAR RESISTANCE OF HARDFACING DEPOSITS ON CAST STEEL ROLL SHELLS

摘要

At Manuelita sugar factory, roll shells made of cast steel have been adopted for top and delivery rolls, because this material presents higher toughness and weldability when compared with gray cast iron. This work shows the results of the evaluation of wear resistance in standard wear tests of white cast iron hardfacing deposits with variation in chromium content, which are presently used on roll shells to reduce the high wear rate and to provide a better grip. The experimental evaluation of wear resistance was done with the ASTM G 65 standard procedure for low-stress abrasion and a specific test machine developed for this research. A methodology for factory trials is proposed aiming to contrast laboratory test results. Additionally, results of grip force tests of several deposit configurations using a jig developed for this purpose are presented. The hardfacing alloy that showed the higher abrasion wear resistance on the ASTM test, was of hypereutectic type with massive primary carbides and the highest chromium content, while in the specific machine test, the hypoeutectic type alloy showed the higher abrasion resistance. Higher grip force was developed by the dotting pattern almost independently of the fibre size of the fibrous material. An unexpected result was the weak grip force developed by the pattern known as combined, which has been widely adopted in practice.