Functionally Graded Martensitic Stainless Steel Obtained Through Partial Decarburization

Abstract

<p>Functionally graded materials offer a way of obtaining materials with superior properties. Decarburization has been used in other steels to create graded materials. These materials offer high strength and improved ductility when compared homogeneous materials of the same type. In this thesis, graded martensitic stainless steel was explored as a way to provide a very high strength material with medium ductility by partially decarburizing the materials. Different processing treatments were tried and the resulting materials characterized and mechanically tested to compare homogeneous and graded martensitic stainless steels. Mechanical testing demonstrated that decarburization has a positive effect on the tensile, rolling and Charpy impact properties. A model was also developed that attempted to capture the deformation behaviour of graded materials. Present data was not available to verify the models validity but the model was used to predict trends of a how different gradients affect fracture stresses and strains. These trends were used in an attempt to find optimum carbon distributions and maximize strength or ductility, as examples.</p>