Failure Investigation of Cast iron Rolls at Coin Making Industry, Pakistan.

The Rolling mill roll deformation is a serious problem and directly impact on production capacity, Mill Environment, Quality and highly impacting financial viability of the production companies. Failures of rolls occur due to improper manufacturing, heat treatment and operational parameters. A failure case of the shaft of a cast iron roller working in a two high rolling mill is presented in this paper. The failed component was the shaft of a roller; abraded from its top edge and face. The failed component was made of SG iron with a layer of chilled cast iron on its outer surface up to the depth of 1 inch. The samples of prematurely failed roll samples collected and examined for their chemistry, inclusion content, microstructures, carbide characteristics, hardness, and the retained austenite content. Standard procedure for analysis was used in this study starting from visual examination, chemical analysis, hardness testing, microstructural study, fractography analysis by SEM. Using these approaches the root cause of failure was pinpointed and precautions were developed in order to avoid future failures