The Corrosion Resistance of The Ukrainian Steel Embedded in Concrete after and before quenching

Abstract

The corrosion resistance of the Ukrainian structural steel(0.22%C) and dual-phase steel which produced from it and embedded in concrete was carried out in this investigation, a test specimens of the Ukrainian steel was prepared and heated to a different temperatures )730 .760 , 790 , 820 , 850, 860 , and8700C( for (50 min) holding time and then quenched in water , a dual-phase steel with a different volumetric fraction of martensite (4.5, 12.6 , 21.4 , 43.2 , 64.8 ,85.3 ,and 100%Ms ) was produced respectively .
Test specimens of Ukrainian steel and of dual-phase steel were initially curing in different mediums (Kufa river water, 3.5%NaCl solution, and Arabian gulf water) for (21 Days) , to know the effect of the volumetric fraction of martensite on the corrosion resistance, also another specimens of Ukrainian steel and of (21.4%Ms) dual-phase steel immersed in concrete which conforming to ( Bs 532: Part 2: 1990) and after (1 Day) cured in water for (7) days ,to find the effect of the embedded in concrete on the corrosion resistance were cured to the same above test .
Corrosion rates were measured by using a modified Tafel extrapolation corrosion test technique (ASTM G 109) , which entails voltage control and current quantifications. In addition, the (CMS-105) system was employed for daily observations on steel bars immersed in similar curing conditions . The parameters measured included corrosion potential (Ecorr), corrosion current (Icorr), polarization resistance (Rp), and corrosion rate (Rcorr.) for all specimens .
The experimental results showed that all the dual-phase steel rebar, embedded or not embedded in concrete, have more times corrosion resistant than Ukrainian structural steel for all used mediums (Kufa river water, 3.5%NaCl solution, and Arabian gulf water), because dual-phase steel contains no carbide and most of the carbon atoms are trapped in the martensite structure , and the Ukrainian steel contains the eutectoid carbide that is susceptible to pitting corrosion , and because of the presence of pearlite phase in the microstructure , also there was an effective for the martensite ,s volume percentage (%Ms) on the corrosion resistance of dual-phase steel embedded in concrete ,when it was increased the corrosion resistance increased also.