This study explores the effects of different in-situ heat treatments on the deposition characteristics and mechanical properties of austenitic stainless steel samples repaired using direct energy deposition (DED). In the DED repair process, defects such as pores and cracks can occur at the interface between the substrate and deposited material. Such interfacial defects are caused by thermal stresses created by differences in thermal expansion between the substrate and powder material, as well as the temperature gradient that results from repeated melting and solidification cycles during deposition. In order to reduce thermal stresses and therefore mitigate crack generation, we implemented in-situ substrate heating and in-situ post heating treatments during the repair process. The in-situ post heating treatment delays the cooling rate by depositing additional material on top of the repaired area immediately after the repair process. Despite the cooling rates being similar with the two in-situ heat treatments, macro-scale cracks were observed in the in-situ post heat-treated samples as well as in the samples repaired without heat treatment (i.e., untreated) owing to a lack of fusion between the substrate and powder material, which led to low tensile properties. In-situ substrate heating provided the highest tensile strength and elongation (increases of 145 % and 767 % compared to those of the untreated specimen, respectively), but the lowest hardness due to grain coarsening from extended exposure to high temperature.

这项研究探索了不同的原位热处理对使用直接能量沉积（DED）修复的奥氏体不锈钢样品的沉积特性和力学性能的影响。在DED修复过程中，诸如孔隙和裂纹的缺陷会在基板和沉积材料之间的界面处发生。此类界面缺陷是由基材和粉末材料之间的热膨胀差异产生的热应力，以及沉积过程中反复熔化和固化循环产生的温度梯度引起的。为了减少热应力并因此减少裂纹的产生，我们在修复过程中实施了原位基板加热和原位后加热处理。原位后热处理通过在修复过程之后立即在修复区域顶部沉积其他材料来延迟冷却速度。尽管冷却速度与两种原位热处理相似，但由于缺乏，在原位热处理后的样品以及未经热处理（即未经处理）的修复样品中均观察到宏观裂纹。基材和粉末材料之间的熔化，导致低拉伸性能。原位加热可提供最高的拉伸强度和伸长率（分别比未处理的试样增加145％和767％），但硬度最低的原因是长时间暴露于高温下导致晶粒粗化。尽管冷却速度与两种原位热处理相似，但由于缺乏，在原位热处理后的样品以及未经热处理（即未经处理）的修复样品中均观察到宏观裂纹。基材和粉末材料之间的熔化，导致低拉伸性能。原位加热可提供最高的拉伸强度和伸长率（分别比未处理的试样增加145％和767％），但硬度最低的原因是长时间暴露于高温下导致晶粒粗化。尽管冷却速度与两种原位热处理相似，但由于缺乏，在原位热处理后的样品以及未经热处理（即未经处理）的修复样品中均观察到宏观裂纹。基材和粉末材料之间的熔化，导致低拉伸性能。原位加热可提供最高的拉伸强度和伸长率（分别比未处理的试样增加145％和767％），但硬度最低的原因是长时间暴露于高温下导致晶粒粗化。未处理）是由于基材和粉末材料之间缺乏融合，导致低拉伸性能。原位加热可提供最高的拉伸强度和伸长率（分别比未处理的试样增加145％和767％），但硬度最低的原因是长时间暴露于高温下导致晶粒粗化。未处理）是由于基材和粉末材料之间缺乏融合，导致低拉伸性能。原位基板加热可提供最高的拉伸强度和伸长率（分别比未处理的试样增加145％和767％），但硬度最低的原因是由于长时间暴露于高温导致晶粒粗化。