Journal of Stress Analysis

Journal of Stress Analysis

The Effect of ECAP Process on the Microstructure and Mechanical Properties of AISI 1020 Plain Carbon Steel

Document Type : Original Research Paper

Author
K. Hajizadeh
Faculty of Materials Engineering, Urmia University of Technology, Urmia, Iran
10.22084/jrstan.2024.28517.1250
Abstract
In the present study, the equal channel angular pressing (ECAP) was applied on AISI 1020 plain carbon steel to refine the grain size down to the sub-micrometer range. ECAP was conducted up to 10 passes at 300 °C in a die with a channel angle of 105°. The microstructure before and after ECAP was observed in two different scales using a light microscope and a transmission electron microscope (TEM). Evaluation of mechanical properties was carried out by tensile tests and microhardness measurements. The results indicate that by applying 10 passes of ECAP, an ultrafine-grained microstructure with a mixture of equiaxed and elongated grains with an average grain size and width of 320 and 270 nm, respectively, is formed in the steel. In addition, the analysis of the X-ray peak profiles of the ECAP-ed samples shows that inside the grains, there are finer microstructural components such as dislocation cells/subgrains. The average size of these components was measured at ~143 nm. In terms of mechanical properties, it was proven that ECAP is very effective in improving the strength and hardness of the steel. It causes a three times growth in yield strength from 280 MPa to 1100 MPa and a 1.67 times increase in hardness from 125 to 395 Vickers. At the same time, the studied material showed an acceptable ductility of εf = 14.8% at these high strength levels. These promising mechanical properties was discussed in terms of characteristics of the ECAP-produced microstructure: extremely fine grains/subgrains, and increased dislocation density.
Keywords
Equal channel angular pressing
AISI 1020
Ultrafine-grained materials
XRD
TEM
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Journal of Stress Analysis
Volume 8, Issue 2
2024
Pages 41-50