Abstract
The effects of carbon contents on the mechanical properties and deformation behavior of medium Mn steels, 6Mn steels with 0.06C, 0.15C, and 0.3C, were investigated in this study. With the increase of the carbon content, not only the ultimate tensile stress, but also the total elongation, was increased (from 22.44% to 40.23%). The enhancement of carbon content promoted the diffusion of C and Mn atoms from ferrite to austenite and led to an increase of C and Mn concentrations in austenite, which increased both the volume fraction (from 15.5 vol% to 39.7 vol%) and the stability of austenite; therefore, the transformation-induced plasticity (TRIP) effect was intensified and larger amount of austenite transform in a greater strain range, which could continuously provide work hardening for the steels, thus preventing necking and improving the ductility of the material.
Highlights
Partitioning of Manganese inAs the most common element in steels, carbon plays a vital role, since the changes of carbon content affect the microstructures, mechanical properties, and deformation behavior of steels
As the C content increases, the size of granular ferrite decreases, and the width of lath austenite increases, which can be ascribed to the partitioning of Mn
With the enhancement of C content, a larger amount of Mn partitions to austenite, resulting in an increase of Mn concentration in austenite, and the enrichment of Mn leads to a larger volume faction of austenite and thicker austenite laths [7]
Summary
As the most common element in steels, carbon plays a vital role, since the changes of carbon content affect the microstructures, mechanical properties, and deformation behavior of steels. As one of the effective solutions to achieve the lightweight of automobiles, medium-Mn steels (4–12 wt% Mn) with excellent combination of high strength and adequate ductility (the values of the products of strength and elongation (PSE) are generally above 30 GPa%). Most of the studies on medium-Mn steels have focused on the chemical compositions, microstructural evolution, mechanical properties, and heat treatment schedules with different C contents from 0.1 wt% to 0.6 wt%. Merwin [4,5] reported the excellent combination of the high strength (above 1000 MPa) and total elongation (above 30%) of the. Shi et al [6] investigated the influence of the C and Mn content on the mechanical properties and work hardening ability of the Fe-(5–7) Mn-(0.2–0.4)
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