Improvement to anti-rust property of hot rolled rebar by compact oxide scale

Abstract

A method was proposed to improve the anti-rust property of hot rolled rebar, which uses oil–water emulsion cooling instead of water cooling after hot rolling. The experiments were carried out by two cooling methods, one cooled by water, the other cooled by oil–water emulsion. The results of wet/dry cyclic accelerated corrosion test showed that the anti-rust property of rebar cooled by oil–water emulsion was better than that by water obviously. The results of OM, SEM and EPMA analysis indicated that these two scales contained three layers: an outer Fe₃O₄ layer, an intermediate FeO layer with island-shaped pro-eutectoid Fe₃O₄, an inner eutectoid Fe₃O₄ layer. For the water cooled rebar, all three layers of oxide scale were relatively thin. Moreover, the scale had plenty of defects such as porosity, and crack. However, for the oil–water emulsion cooled rebar, all three layers of oxide scale were relatively thick and compact, which played an important role in protecting the rebar from atmospheric rust.

Keywords

hot rolled rebar / anti-rust property / compact oxide scale / oil–water emulsion cooling

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