Microstructure, Mechanical Properties, And Corrosion Behavior Of Cryorolled Low Carbon Steel Subjected To Heat Treatment
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Date
2018-12-01
Authors
Motham, Kanchana
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Low carbon steel has been extensively used in various industries, but its limited
strength restricted the potential development in applications. In recent years, ultrafine
grained (UFG) structural materials have been studied, because they are expected to
provide superior mechanical properties. The present works aim at producing UFG in
low carbon steel using cryorolling and investigated its effect on heat treatment and
thickness reduction on microstructure, mechanical properties and corrosion behavior.
The details of microstructural characteristics and mechanical properties of low carbon
steel were investigated using optical microscope (OM), scanning electron microscope
(SEM), electron back scattered diffraction (EBSD), X-ray diffraction (XRD), Vickers
microhardness and tensile test. Low carbon steel underwent pre-annealing at 550°C,
750°C, and 900°C at 15, 30, 60 and 120 minutes followed by cryorolling. Sample
treated at 550°C (60 minutes) shows the optimum properties and was chosen for futher
investigation on different thickness reduction; 50%, 60%, 70%, 80% and 90%. The
highest hardness and tensile strength attained at 90% reduction with the values of 208.5
Hv and 826.5 MPa respectively which result in the smallest crystallite size (38.16 nm)
and highest lattice strain (20.58 x 10-4). Corrosion resistance decreases with thickness
reduction. Post-annealed at 450°C shows recrystallization state for 90% reduction and
achieved ultrafine grain with hardness and tensile strength of 157.9 Hv and 587.7 MPa
respectively.