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High speed steels are used for the manufacture of the work rolls used in hot rolling steel mills. An understanding of the degradation phenomena of work rolls is essential, particularly in fields related to the oxidation of the surface, given the importance of the surface quality of the rolled product at the end of the process and its close relation with the changes experienced by the surface of the rolls. The high temperature oxidation behaviour of a work roll grade high speed steel was studied using gravimetric means under isothermal conditions at 550 and 615°C in dry air and in a mixture of dry air and water vapour. At both temperatures, the mass gain of the samples exposed to the mixture of dry air and water vapour was considerably higher than that of the samples exposed to dry air. For all the experimental conditions, oxide growth was better described by the parabolic rate law. The composition of the oxide layer was influenced by the oxidant atmosphere, as the layer in the water vapour containing environment included an iron-chromium spinel (M 3 O 4 ), magnetite and hematite, whereas the layer in the dry air condition consisted of iron-chromium spinel, hematite and vanadium oxide. The effect of composition of the oxidant atmosphere on the rate of oxidation of the steel and the components of the oxide scale is discussed.

The deformation of the oxide layer grown in ultra low carbon steel was studied by means of electron backscattered diffraction analyses. Samples of the steel were reheated for shorts periods of time at 1050°C in a chamber designed to obtain thin scale layers before deforming them by plane strain compression at temperatures ranging from 650 to 1050°C. Microstructural analyses showed that the oxide layer was made almost exclusively of wustite that is ductile when deformed above 900°C. It is found that wustite develops texture components of the cube and rotated cube type while growing; these components rotate towards h201i {100} components once a certain degree of deformation is achieved. Undeformed ferrite close to the oxide layer shows weak h201i {100} components that rotate into weak rotated cube components when the substrate is deformed in the austenite range and to strong h554i {225} components when deformed in ferrite. Rolling trials carried out in an experimental mill showed similar trends.

There is great interest in the steel industry of incorporating new products that go beyond the properties of existing ones. Among these properties, corrosion resistance is extremely important for countries that, like Chile, have an extensive ocean coastline. In costal zones, the chloride ions in air produce corrosion that reduces the service life of structures. For this reason, it is of utmost importance to study the influence of different alloying elements such as nickel, which lead to improve steel's resistance to marine corrosion. In this context the development of new types of steel is hindered if the evaluation of their corrosion resistance takes very long times. This paper presents a methodology based on accelerated wet-dry cycle corrosion experiences to simulate the behaviour of steel over time in a marine environment. The results of the proposed methodology allow adequate prediction of corrosion thickness in ASTM A242 and A588 steels exposed for years to a specific marine environment.