2021 Nashville AISTech

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Yield Stress in Ferritic Steels Influenced by Grain Boundary Walls (Room 208 B)

29 Jun 21
11:00 AM - 11:30 AM

Tracks: Metallurgy - Processing, Products & Applications: Physical Metallurgy of Steels I

Accepted theories explaining the cause for the unique upper and lower yield points in hypoeutectic plain carbon steels are considered inadequate. Atomic force microscopy revealed that grain boundaries between adjoining grains in these steels consist of brittle, probably cementite (Fe3C), walls enclosing the grains. These walls inhibit the movement of dislocations between adjoining grains until the walls fracture. Experiments show this may be the primary cause of a sharp upper yield point at the elastic line followed by rapid drop in stress below the Lüders region. Thereafter, the stress rises elastically into the Lüders plastic deformation region.