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

在高吸能结构构件材料中，高锰钢是一类很有前途的合金。由于位错滑移以外的其他塑性流动机制的激活，HMN具有高强度和高成形性的组合。然而，尽管HMN具有这些优异的性能，但它在工业上的应用却很少。主要原因是合金化元素的成本较高，以及减少铸造偏析的后处理耗能。添加制造(AM)为传统制造工艺(如连铸和后续成形)提供了一种替代方案。一个有趣的体系是Fe-Mn-Al-C，具有高含量的Mn(约20-30wt.-%)、Al(约6-12wt.-%)和C(约0.6-1.3wt.-%)。该合金组的密度降低约为。6，6g/cm~3，并有可能通过析出共格的Kappa碳化物来强化。本项目将对X110MnAl30-8合金进行粉末激光金属沉积(LMD)处理。主要目的是深入了解在逐层堆积过程中，工艺参数、局部冶金、快速冷却和循环再加热对凝固和析出行为的影响。工艺参数将根据密实度的增加在合理的范围内变化。分析范围从纳米尺度(细小沉淀、偏析)、微观尺度(颗粒、层界)到宏观尺度(力学性能)。通过采用相关的工艺参数，将产生和分析在层状积聚的T-t循环中形成的不同Kappa碳化物分数的X110MnAl30-8样品。机械性能将通过硬度测量以及压缩和拉伸试验来确定。对变形后的试件进行了显微组织和断裂面分析，以了解变形和破坏机制。

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.