Yuhui Wang

Hetero-deformation induced (HDI) stress and the effect of microstructural morphology on it were investigated in a near-alpha titanium alloy featuring lamellar and equiaxed initial microstructures. The development of HDI stresses were confirmed in the two types of microstructures under tensile tests. While both microstructures exhibit comparable HDI stress magnitudes during initial tensile deformation, the equiaxed one demonstrates obviously enhanced HDI strain hardening compared to its lamellar counterpart as deformation progressed. Two factors are mainly responsible for the observed divergence in HDI stress evolution between the two microstructures. First and foremost is the surface-to-volume ratio of phase interface ( s _V ), where the equiaxed structure shows significantly higher s _V than its lamellar counterpart, which can offer more potential sites and better spatial interconnectivity of phase interfaces for GNDs development. The other factor is the microstructural size scale, in which the average layer thickness of the lamellar structure is considered being too small, as compared to the average grain diameter in the equiaxed one, to provide sufficient space for GND pileups to fully develop, which limits HDI strain hardening. This finding provides critical insights into microstructural design strategies for optimizing the development of HDI stress.

1. Copper and its alloys are indispensable structural-functional materials in modern industry, providing essential support for technological advances in a wide range of fields [1,2]. For example, C...

This study investigates the mechanical behavior and deformation mechanisms of Fe-30Mn-0.05C (30Mn0.05C) and Fe-34Mn-0.7C (34Mn0.7C) steels at room temperature (RT) and liquid nitrogen temperature (LNT). The 30Mn0.05C sample exhibited a significant enhancement in both strength and ductility at LNT, achieving a total elongation of 85%. In contrast, the 34Mn0.7C sample demonstrated superior ductility (90%) at RT, with a marginal reduction in plasticity but a remarkable increase in strength (>1100 MPa) at LNT. Compared to the 30Mn0.05C, the 34Mn0.7C, characterized by higher carbon content, displayed more pronounced dynamic strain aging (DSA) effects. Additionally, a greater density of deformation twins was activated at LNT, revealing a strong correlation between deformation twinning and DSA effects. This interplay accounts for the simultaneous strength improvement and ductility reduction observed in the 34Mn0.7C at LNT. Furthermore, the 34Mn0.7C sample exhibited a significantly refined grain structure after rolling, contributing to a substantial strength increase (approaching 1500 MPa) at the expense of ductility. This trade-off can be attributed to the pre-introduction of a higher density of dislocations and deformation twins during rolling, which facilitated strengthening but limited further plastic deformation.

The Charpy impact toughness of single-phase austenitic Fe-32Mn-0.6C steel was systematically investigated across a wide temperature spectrum from 25 °C to −196 °C using Charpy V-notch impact tests. The material exhibited a remarkable temperature dependence of impact energy, decreasing dramatically from 120 J at ambient temperature (25 °C) to 13 J under cryogenic conditions (−196 °C). Notably, a steep transition in impact energy occurred within the critical temperature window of −100 °C to −150 °C. Microstructural analysis revealed that synergistic effects of high strain rates and low temperatures significantly restrict dislocation slip and multiplication mechanisms, while also suppressing deformation twinning activation. This restricted plasticity accommodation mechanism fundamentally differs from the deformation characteristics reported in conventional low-carbon high-manganese steels and other face-centered cubic (FCC) alloy systems.