材料科学
淬透性
延展性(地球科学)
微观结构
冶金
碳化物
沉淀硬化
动态应变时效
可塑性
复合材料
合金
蠕动
作者
Huihui Zhi,Jinshan Li,Wanmin Li,Mohamed Elkot,Stoichko Antonov,Heng Zhang,Ming-Yang Lai
出处
期刊:Acta Materialia
[Elsevier]
日期:2023-02-01
卷期号:245: 118611-118611
被引量:3
标识
DOI:10.1016/j.actamat.2022.118611
摘要
We studied the initial microstructures, mechanical responses and deformation-induced microstructures of the medium-Al Fe-21Mn-6Al-1C-xSi (x = 0, 1.5, 3 wt.%) lightweight steels both in their solution-treated and aged states. Our results reveal that nano-sized long-range ordered domains exist in the solution-treated steels, which feature L12 type ordering in the 0Si and 1.5Si steels and L′12 type ordering in the 3Si steel. Aging at 550 °C for 20 h has little effect on the microstructures of the 0Si steel, but leads to κ′-carbide precipitation in the 1.5Si steel. For the 3Si steel, aging at 550 °C for 1 h already results in the precipitation of uniformly-distributed nano-sized κ′-carbides (4.2 nm). The strength, ductility and strain hardenability of the solution-treated steels all enhance with increasing Si content. The yield strength (YS) of the aged steels with κ′-carbides enhances with increasing aging time, accompanied by the reduction of ductility. The short-time (1 h) aged 3Si steel exhibits excellent strength-ductility synergy, with YS > 900 MPa and total elongation > 50%. The increase in YS with Si addition originates from the grain boundary, solid-solution and order strengthening. For the 0Si steel, the strain hardening is governed by the evolution of high-density dislocation walls and microbands. The occurrence of both dynamic slip band refinement (DSBR) and twinning-induced plasticity effects in the 3Si steel accounts for the increase of strain hardenability with Si-alloying. The DSBR effect still exists and the progressively-formed slip bands are homogeneously distributed in the short-time aged 3Si steel, explaining its high ductility.
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