Investigation of in-situ precipitation behaviour in density-reduced high-strength κ-phase (Fe,Mn)3AlCx reinforced high-manganese steels (κ-HMnS) during laser-based Additive Manufacturing

在用于具有高能量吸收的结构部件的材料中，高锰钢（HMnS）是有前途的合金类别。由于除了位错滑移之外的其他塑性流动机制的激活，HMnS显示出高强度与高成形性的组合。然而，尽管HMnS具有这些优异的性能，但仅发现了少数工业应用。主要原因是合金元素的成本高，以及用于减少铸造产生的偏析的后处理能耗高。增材制造（AM）提供了传统制造路线（例如连续铸造和后续成形）的替代方案。一个有趣的系统是具有高Mn含量的Fe-Mn-Al-C（约. 20-30重量%），Al（ca. 6-12重量%）和C（ca. 0.6-1.3重量%）。该合金组显示出约为100%的减小的密度。6.6 g/cm 3，并通过沉淀连贯的卡帕碳化物来强化。在本项目中，X110 MnAl 30 -8合金将通过粉末基激光金属沉积（LMD）进行加工。主要目标是阐述一个深刻的理解的凝固和沉淀行为的功能的工艺参数，局部冶金，快速冷却和循环再加热过程中的逐层建立。工艺参数将根据致密体积的形成在合理限度内变化。分析范围从纳米尺度（细沉淀，偏析）和微观尺度（晶粒，层边界）到宏观尺度（机械性能）。通过调整相关工艺参数，将生产和分析具有不同Kappa碳化物分数的X110 MnAl 30 -8样品（在分层堆积的T-t循环期间形成）。机械性能将通过硬度测量以及压缩和拉伸测试来确定。对变形后的试样进行了显微组织和断口分析，以了解变形和失效机理。

Among materials for structural components with high energy absorption high manganese steels (HMnS) are a promising alloy class. Due to the activation of other plastic flow mechanisms besides dislocation glide HMnS show high strength in combination with high formability. However, despite of these outstanding properties HMnS have found only a few industrial applications. The main reasons are high costs for alloying elements and energy consuming post treatment to reduce segregation, which results from casting. Additive manufacturing (AM) offers an alternative to conventional manufacturing routes (e.g. continuous casting and subsequent forming). An interesting system is Fe-Mn-Al-C with high content of Mn (ca. 20-30 wt.-%), Al (ca. 6-12 wt.-%) and C (ca. 0.6-1.3 wt.-%). This alloy group exhibits a reduced density of approx. 6,6 g/cm3 and the potential for strengthening through the precipitation of coherent Kappa carbides. In this project the alloy X110MnAl30-8 will be processed by powder-based laser metal deposition (LMD). The main goal is to elaborate a profound understanding of the solidification and precipitation behavior as a function of process parameters, local metallurgy, rapid cooling and cycling reheating during the layer-by-layer build-up. The process parameters will be varied in reasonable limits according to the build-up of dense volumes. The analysis ranges from nano scale (fine precipitations, segregation) and micro scale (grains, layer boundaries) to macro scale (mechanical properties). By adapting relevant process parameters samples of X110MnAl30-8 with different fractions of Kappa carbides - formed during the T-t-cycles of the layerwise build-up - will be produced and analysed. The mechanical properties will be determined via hardness measurement and compressive and tensile tests. Microstructure and fracture plane analysis of the deformed samples is performed to understand deforming and failure mechanisms.