A simple method to produce austenite-based low-density Fe–20Mn–9Al–0.75C steel by a near-rapid solidification process
A simple method to produce austenite-based low-density Fe–20Mn–9Al–0.75C steel by a near-rapid solidification process
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DOI：
10.1016/j.msea.2016.10.044
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发表时间：
2017-01
期刊：
影响因子：
6.4
通讯作者：
Libing Liu;Chun-ming Li;Yang Yang-Yang;Zhiping Luo;C. Song;Q. Zhai
中科院分区：
文献类型：
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作者：
Libing Liu;Chun-ming Li;Yang Yang-Yang;Zhiping Luo;C. Song;Q. Zhai
奥氏体基低密度钢由于其优异的机械性能和降低的密度而成为有前途的结构材料，而通常难以生产具有高Mn和Al含量的此类钢，因为它们相对低的热导率和高的变形抗力。本文对近终形法生产贝氏体基低密度钢进行了新的尝试。采用液态金属直接注射铸造法制备了厚度为2 mm的Fe-20 Mn-9Al-0.75C低密度钢近快速凝固薄带。显微组织分析表明，铸态薄带主要由γ奥氏体和δ铁素体组成的复相组织，δ铁素体中存在有序的DO 3纳米颗粒，γ基体中存在有序的κ碳化物。一些机械性能被发现是相似的，并且其中一些被发现甚至比那些具有相似组成的钢更好，但是通过文献中报道的具有多个热处理和轧制工艺的传统方法制备。在400 °C和600 °C下退火促进了有序纳米尺寸的DO 3和κ的沉淀。由于κ碳化物的有序化阻止了位错和平面缺陷的滑移，导致伸长率降低，而屈服强度、极限抗拉强度和显微硬度提高。当退火温度达到800 °C时，共析转变（γ → α+κ）发生，粗化的颗粒状κ型碳化物使总延伸率急剧下降。本工作为生产高性能低密度钢提供了一种简单有效的方法。
Austenite-based low-density steels are promising structural materials due to their excellent mechanical properties with reduced densities, whereas it is normally hard to produce such steels with high Mn and Al contents because of their relatively low thermal conductivities and high deformation resistance. In this paper, a new attempt has been made to produce the austenite-based low-density steels by a near-net shape method. Near-rapidly solidified strips, in 2 mm thickness of Fe–20Mn–9Al–0.75C low-density steel, were directly obtained from liquid metal by injection casting. Microstructural analyses revealed that there were mainly duplex phases composed of γ austenite and δ ferrite in as-cast strip, with ordered DO3nanoparticles in δ, and ordered κ carbides in γ matrix, respectively. Some of the mechanical properties were found to be similar, and some of them were found to be even better than those steels with similar compositions but prepared by traditional methods with multiple heat treatments and rolling processes reported in literature. Annealing at 400 °C and 600 °C promoted the precipitation of ordered nano-sized DO3and κ. As the ordering of κ carbides prevent dislocation and planar defects gliding, giving rise to decreased elongation while enhanced yield strength, ultimate tensile strength and micro-hardness. An eutectoid transformation (γ → α+κ) occurred when the annealing temperature reached 800 °C; as a consequence, the coarsened granular κ carbides drastically declined the total elongation. The present work demonstrated that a simple effective way to produce high-performance low-density steels.