Gadadhar Sahoo

Corrosion of Phosphoric Irons in Acidic Environments

The corrosion behavior of phosphoric irons (i.e., Fe-P alloys containing low phosphorus in the range 0.1 to 0.5 wt. %), prepared by ingot metallurgy route, was evaluated in acidic and chloride environments, e.g., 0.25 M H2SO4 of pH 0.6, 0.5 M Na2SO4 of pH 3 and 3.5 % NaCl of pH 6.8. A plain carbon steel and a low alloy (Cu-Cr) steel were also studied for comparison purpose. The effect of Cu and Cr additions was beneficial in a highly acidic condition. While similar corrosion rates observed for plain carbon steel and low alloy steel in 0.5 M Na2SO4 of pH 3, a slightly higher corrosion rate was observed for phosphoric irons. All alloys exhibited lowest and similar corrosion rates in neutral 3.5 % NaCl corrosive media. The linearity of Tafel slopes in the cathodic region varied with the pH of the solution. Corrosion rates were higher at lower pH due to the major contribution of hydrogen evolution reaction to the cathodic current.

Corrosion of Phosphoric Irons in Cement Grout

Abstract Corrosion behavior of three cement-grouted phosphoric irons (Fe-0.11P-0.028C, Fe-0.32P-0.026C, and Fe-0.49P-0.02C, wt%) was studied using the potentiostatic polarization technique in 5% so...

Occurrence of two-stage hardening in C-Mn steel wire rods containing pearlitic microstructure

The 8 and 10 mm diameter wire rods intended for use as concrete reinforcement were produced/ hot rolled from C-Mn steel chemistry containing various elements within the range of C:0.55-0.65, Mn:0.85-1.50, Si:0.05-0.09, S:0.04 max, P:0.04 max and N:0.006 max wt%. Depending upon the C and Mn contents the product attained pearlitic microstructure in the range of 85-93% with balance amount of polygonal ferrite transformed at prior austenite grain boundaries. The pearlitic microstructure in the wire rods helped in achieving yield strength, tensile strength, total elongation and reduction in area values within the range of 422-515 MPa, 790-950 MPa, 22-15% and 45-35%, respectively. On analyzing the tensile results it was revealed that the material experienced hardening in two stages separable by a knee strain value of about 0.05. The occurrence of two stage hardening thus in the steel with hardening coefficients of 0.26 and 0.09 could be demonstrated with the help of derived relationships existed between flow stress and the strain.

Comparison of Thermal Expansion Behavior of Phosphoric Irons with Conventional Concrete Reinforcement Steel

Phase transformations using dilatometry and microstructures in two phosphoric irons (Fe-0.11P-0.028C, Fe-0.49P-0.022C) and a low carbon steel (Fe-0.148C-0.542Mn–0.128Si), all in weight percent, were studied. The linear thermal expansion coefficients of phosphoric irons was comparable to that of carbon steel. The phase transformation temperatures were not well defined in the case of phosphoric irons. While low-phosphorus steel exhibited single-phase microstructure, high-phosphorus steel exhibited dual-phase ferritic microstructure consisting of prior ferrite and prior austenite. The low carbon steel revealed a ferrite-pearlite microstructure at the center of the cross section and tempered martensite at the rim.