Development of Ultrafine Grain IF Steel via Differential Speed Rolling Technique

The aim of this paper was to investigate the microstructural development and properties of interstitial free (IF) steel fabricated using the DSR (differential speed rolling) process. Severe plastic deformation of the DSR passes was imposed on the sample for up to four passes, leading to ~1.7 total strain with a speed ratio of 1:4 between the two rolls. Microstructural observation revealed that the equiaxed grain size of ~0.7 µm, including the formation of grain boundaries with a high angle of misorientation, was reached after four operations of DSR, which was attributed to the grain subdivision of severely elongated ferrite grain. Since the deformation mode of the DSR operation was dominated by severe shear deformation, the main shear texture of the bcc components appeared in all DSR operations in which the α-fiber of the {110} slip became a main component in accommodating the severe plastic deformation of the DSR process. The intensity of the shear texture, the {110} and {112} slip, increased by increasing the number of passes. Moreover, the γ-fiber of the <112>-type planes was activated as a result of the alternation of the shear direction during sample rotation. The microhardness and room temperature tensile tests revealed that the strength of the IF steel improved as the amount of strain increased, and this was attributed to the grain refinement and texture characteristics of the samples after the DSR processing.

The effect of severe plastic deformation on the IF steel properties, evolution of structure and crystallographic texture after dual rolls equal channel extrusion deformation

This paper presents some results of the influence of severe plastic deformation on the microstructure evolution, grain refinement aspect, and mechanical properties of ultra-low carbon steel. Ti-stabilized experimental IF steel was deformed at a room temperature with unconventional SPD process—dual rolls equal channel extrusion (DRECE). Mechanical properties and structure of ferritic steel in initial state and after selected steps of deformation were investigated. The mechanical properties were determined by static tensile tests carried out at a room temperature and microhardness research. The structural investigations involved using scanning transmission electron microscopy observations, electron back scattered diffraction and measurements of the crystallographic texture. The DRECE process affects the evolution of the structure. The microstructural investigations revealed that the processed strips exhibited a dislocation cell and grain structures with mostly low angle grain boundaries. The electron backscattering diffraction (EBSD) examination showed that the processed microstructure is homogeneous along the strips thickness. The mechanical properties of the DRECE-processed IF steel strips increased with an increase the number of passes.

Simulation of Subrapid Solidification and Secondary Cooling for the Strip Casting of IF Steel

A combination of droplet solidification tester and confocal laser scanning microscope was used to simulate subrapid solidification and secondary cooling process pertinent to the strip casting. The IF steel droplet had a delamination structure and the bottom part went through sub-rapid solidification. During secondary cooling, γ/α transformation mechanism belonged to interface-controlled massive transformation and the ferrite grains grew quickly. With the increase of cooling rate, the γ/α transformation temperature decreased and the incubation period and phase transformation duration reduced. The hardness showed a slight increase due to fine-grain strengthening. With coiling temperature increasing from 600 °C to 800 °C, the grain size became larger, precipitates became coarse, and defects in grain were recovered. Consequently, the hardness decreased.

Utilization of induction furnace steel slag based iron oxide nanocomposites for antibacterial studies

Metals and metal oxide-based nanocomposites play a significant role over the control of microbes. In this study, antibacterial activity of iron oxide (Fe2O3) nanocomposites based on induction furnace (IF) steel slag has been carried out. IF steel slag is an industrial by-product generated from secondary steel manufacturing process and has various metal oxides which includes Al2O3 (7.89%), MnO (5.06), CaO (1.49%) and specifically Fe2O3 (14.30%) in higher content along with metalloid SiO2 (66.42). Antibacterial activity of iron oxide nanocomposites has been revealed on bacterial species such as Micrococcus luteus, Bacillus subtilis and Staphylococcus aureus. Micrococcus luteus has undergone maximum zone of inhibition (ZOI) of 12 mm for 10 mg/mL concentration of steel slag iron oxide nanocomposite. Growth inhibitory kinetics of bacterial species has been studied using ELISA microplate reader at 660 nm by varying the concentration of steel slag iron oxide nanocomposites. The results illustrate that IF steel slag is a potential material and can be utilized in building materials to increase the resistance against biodeterioration. Graphic abstract