Effect of post-rolling cooling on the hot-rolled microstructure and texture of a new medium-carbon steel

V Javaheri,A Kaijalainen,M R Kamali,S Sadeghpour,J Kömi

doi:10.1088/1757-899x/1121/1/012037

V Javaheri, A Kaijalainen + Show 3 more

Open Access

https://doi.org/10.1088/1757-899x/1121/1/012037

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Abstract

Thermomechanical processing consisted of hot-rolling in the austenitic region with deformation both above and below the non-recrystallization temperature. Immediately after rolling, specimens were directly quenched in water to three different temperatures of 560 °C, 420 °C and room temperature. The first two samples, which were quenched to 560° C and 420°C, immediately cooled slowly in the furnace. The microstructure of samples quenched to 560 °C mostly comprised of upper bainite whereas the samples quenched to 420 °C mainly consisted of lath-type bainite. The microstructure of sample direct-quenched to room temperature was mainly martensite. The transformation texture of all samples at the midthickness position showed the same general texture, consisted of mainly ᵅ and ᵞ fibers components with high intensities close to the transformed copper {112}<110>ᵅ, transformed brass {111}<112>ᵅ and rotated cube {001}<110>ᵅ components. However, the direct-quenched sample produced slightly more intense texture compared to the bainitic samples. The local texture of samples near the rolled surface owing to sever deformation showed the shear features consisting of major components of {112}<111>ᵅ, {110}<112>ᵅ and {110}<111>ᵅ.

Highlights

Thermomechanical controlled processing (TMCP) is a technological way to enhance the strength and toughness of steel plates at the same time by i) controlling the prior austenite structure through the rolling parameters and ii) controlling the subsequent phase transformation via control of the cooling path
Throughout the rough rolling stage, at above Tnr, deformation and repeated recrystallization is taken place simultaneously resulting in very fine austenite grain structure which will be elongated into narrow stretched grain structure after further deformation below Tnr
The micrographs of the final structures in the form of electron backscatter diffraction (EBSD) image quality along with the phase fraction calculation on the basis of normalized image quality numerical analysis are presented in figure 2

Summary

Introduction

Thermomechanical controlled processing (TMCP) is a technological way to enhance the strength and toughness of steel plates at the same time by i) controlling the prior austenite structure through the rolling parameters and ii) controlling the subsequent phase transformation via control of the cooling path. The local texture of samples near the rolled surface owing to sever deformation showed the shear features consisting of major components of {112}a, {110}a and {110}a. Owing to orientation relationships between the parent austenite and the daughter ferritic products such as bainite and martensite, the final ferritic microstructure shows crystallographic texture [3].

Results

Conclusion