Comparative tensile tests on reinforcement bars, with and without microalloying with niobium

"Rebar", is used in concrete structures to enable them to support tensile stresses since concrete does not generally perform well in tension. The video illustrates the enhanced strength and ductility obtained by microalloying the steel reinforcement bar with niobium, so that in its final form, the 12.5 mm diameter bar has a finer and more homogeneous microstructure of ferrite and pearlite than a similarly processed niobium-free rebar.
Video reproduced with the kind permission from Leonardo Magalhães Silvestre of CBMM, Brazil. The video shows the two rebars being tested in tension.

[hkonca]

Actually the same day I learnt that ribbed bars and wires are tested as they are, in service condition.And as you said when there is a lot of plasticity, surface is not that much important. Thanks a lot.

[bhadeshia]

Good point, but the only comment I would make is that there is a lot of plasticity and necking, indicating that surface defects do not play a role in initiating fracture.

[hkonca]

I'm not sure how healty are these tests as they have lots of surface defects. I'd love to see the same test with standard tensile test bone and smooth surface.