Effects of grain size and temperature on mechanical properties of Fe–20Mn–0.7C TWIP steel

ABSTRACT

Fe–20Mn–0.7C twinning-induced plasticity (TWIP) steel with the grain sizes in the range 1.7–10.2 μm was produced by cold rolling and annealing. The effects of grain sizes on the mechanical properties of the TWIP steel were studied by tensile test at room temperature (RT) and –180°C. The yield strength increased with decreasing grain size at RT and –180°C, and the corresponding Hall–Petch relationships were established at both temperatures and are as follows (i) σ_0.2= 205 + 453 d ^–1/2 (at RT) and (ii) σ_0.2= 317 + 755 d ^–1/2 (at –180°C). When the temperature decreased from RT to –180°C, the stacking fault energy decreased from 24to 17.9 mJ/m², approximately 25%, and the deformation mode is transformed from deformation twins to martensite transformation.

KEYWORDS:

• Twinning-induced plasticity (TWIP) steel
• mechanical properties
• cold rolling
• annealing
• Hall–Petch relationship

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Nature Science Foundation of China [grant number 51871194], the National Natural Foundation of Hebei Province, China [grant number E2018203312] and the Fundamental Research Funds for the Central Universities [grant number N180204015].