Comparison on Tensile Characteristics of Plain C-Mn Steel with Ultrafine Grained Ferrite/Cementite Microstructure and Coarse Grained Ferrite/Pearlite Microstructure.

Yan Tian,Dengfeng Yin,Andrej Atrens,Wenjian Liu,Mingchun Zhao,Jimou Zhang,Min Zhang,Hongying Li

doi:10.3390/ma14092309

Abstract

This work investigated the tensile characteristics of plain C–Mn steel with an ultrafine grained ferrite/cementite (UGF/C) microstructure and coarse-grained ferrite/pearlite (CGF/P) microstructure. The tensile tests were performed at temperatures between 77 K and 323 K. The lower yield and the ultimate tensile strengths were significantly increased when the microstructure was changed from the CGF/P to the UGF/C microstructures, but the total elongation and the uniform elongation decreased. A microstructural change from the CGF/P microstructure to the UGF/C microstructure had an influence on the athermal component of the lower yield and the ultimate tensile strengths but not on the thermal component. The UGF/C microstructure with a higher carbon content provided a higher strength without losing ductility because cementite particles restrained necking.

Highlights

Plain C–Mn steels containing no costly alloying elements are economical structural materials
The conventional microstructure of plain C–Mn steels consists of coarse ferrite grains and pearlite colonies, i.e., coarse ferrite grains and alternate lamellae of cementite and ferrite, which have been in commercial production for centuries
A higher carbon content in steel resulted in a higher volume fraction of pearlite in the original microstructure after the phase transformation, which facilitated a more homogeneous cementite distribution during caliber warm rolling because the pearlitic lamellae broke into cementite particles that localized within the pearlite colonies

Summary

Introduction

Plain C–Mn steels containing no costly alloying elements are economical structural materials. Steels must meet the requirements of strength and ductility, which are measured in a tensile test [4,5] These mechanical properties are an important performance target for steels. It is interesting that what is different in terms of the strength, elongation and tensile fracture of the microstructure in plain C–Mn steels changes from the CGF/P microstructure to the UGF/C microstructure. Another interesting element is how to make ultrafine grains have a high strength without losing ductility. This work investigated the tensile characteristics of plain C–Mn steel with a UGF/C microstructure and a CGF/P microstructure, and aimed to obtain a high strength without a loss of ductility for plain C–Mn steels with a UGF/C microstructure

Methods

Results

Conclusion