Characterization of oxide layers formed on pilot plant Steckel rolled 304 stainless steel samples

• The evolution of oxide scales on 304 austentic stainless steel during Steckel mill rolling has been investigated by performing pilot trials at Swerim Luleå. The influence of Steckel furnace conditions, i.e. temperature, time and excess oxygen, at reheating between subsequent roll passes have been evaluated and the resulting surface structures have been characterized.High resolution scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the oxide scales with respect microstructure and chemical composition. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to analyze the chemical composition at the stainless steel / oxide interface region.In common for all Steckell rolled samples investigated was a pronounced rough surface morphology and the surface roughness was found to increase with more iterations of rolling. Also, the amount of oxides in the rolled surface tends to increase with longer heating times and more iterations of rolling. Surface areas, less distorted by the rolling contact, displayed an oxide scale with an outer rather well-defined oxide layer with relatively large grains and an inner, less well defined, oxide layer. EDS-analysis show that the outer oxide mainly consists of Fe2O3, whereas the inner oxide layer corresponds to a chromium rich (Cr,Fe)2O3 oxide combined with areas of partly oxidized stainless steel. ToF-SIMS analysis of the stainless steel / oxide interface region show the presence of B, Ca and Cu in connection to the oxides.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Rolling

Stainless steel

Oxide layer

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vet (ämneskategori)

rap (ämneskategori)