Abstract
Reinforced bars (rebars) are Thermo-mechanically
treated (TMT) bars hot rolled from steel billets produced
from scrap melted in an Electric Arc Furnace (EAF) at a
temperature of about 1600 ℃ (usually 1580℃). Weight per
meter of a low carbon steel rebar is one aspect which has
been neglected by some steel producers during the tensile
testing in the rod mill. Determination of weight per metre is
explicitly required for a TMT rebar. Any reduction in mass
will mean a lowering in capacity of the steel reinforcing bar.
A series of “heat” numbers or batches of molten steel from
an EAF for the production of steel sample A, (Y10 and Y 12
rebars), were observed at a Steel plant to investigate the
effect of weight per meter of reinforced bar on the
mechanical properties and microstructure. The rolling
speed range was 3m/s to 14 m/s for different “heats”. Two
other steel samples B and C were sourced from the local
market to compare with Sample A. Samples collected from
different sources on the local market, however, showed lower
values of weight per meter different from the prescribed
standards. This did not only affect the ultimate tensile
strengths which were higher than normal but also the
microstructure which deviated from the standard for this
material. Sample A, did not only show a good combination of
tensile strength and yield stress of 450MPa and a maximum
tensile strength of 650MPa but also a standard pearliteferrite
microstructure, while sample B and C exhibited
excessive high strengths and brittle behaviour and can be
prone to failure.