Structure Effects over Behavior of Graphite Gray Iron in Running

The work aims at emphasizing the structure changes of graphite gray iron, as a result of make-casting conditions and their effects over behavior in running of several cast items. Researches consisted of complex characterization of several gray iron specimens sampled from damaged items comparatively to other suitable ones. Chemical composition, crack aspect, tensile strength, structure, kind, micro hardness of structural constituent were analyzed. Laboratory researches made by optical and electronic microscopy emphasized the showing up of some unsuitable structures with fragile structural constituents and areas unpurified by exogenous inclusions as well as degenerated graphite. All of these steady structural changes had a powerful fragility effect over the material. This fact was confirmed by mechanical characteristics and analysis of cracking area. Results corroborating allowed finding the causes of graphite gray iron cast items damage as a result of a faulty make-casting technological management and incomplete heating treatment