激光原位合金化Fe-Mn合金的元素质量损失

Elemental mass loss in in-situ laser alloying Fe-Mn alloys

多材料打印是目前金属增材制造的重要发展方向,利用多材料打印技术可以节约材料,充分发挥材料和结构耦合设计特点、实现综合优异的性能或功能。其中激光原位合金化技术是实现多材料打印的核心方法之一,利用激光作为热源逐层熔化粉末形成三维零件,成形的金属零件致密度高、尺寸精度高、表面粗糙度好。由于锰元素的蒸气压较高,在高温热源的作用下蒸发效应更强烈,针对多材料激光原位合金化制备技术中的元素蒸发问题,以纯金属粉末铁和锰为原材料,采用高通量增材制造设备,分别进行了Fe10Mn(质量分数,下同)和Fe20Mn混合异质粉末的激光选区熔化试验,重点对比分析了不同激光功率、扫描速度、成分配比等参数对成形样品的质量损失及成分精度的影响。研究结果表明,锰质量分数为20%时的质量损失率低于锰质量分数为10%的质量损失率。高锰含量样品在成形过程中蒸发更加剧烈,反冲压力更大,熔池更窄更深。激光原位合金化成形合金最佳的工艺参数为激光功率220 W,扫描速度500 mm/s,扫描间距0.08 mm,层厚0.03 mm,成形试样的密度最高可达7.81 g/cm^(3),致密度最高可达99.78%。最佳工艺参数条件下,原位合金化Fe20Mn合金的质量损失率仅为1.50%。因此,在Fe-Mn合金中,锰相较于铁具有更大的蒸发倾向,优化了Fe-Mn合金的激光打印工艺参数,为提高易蒸发元素的成分精度控制提供了参考。

Multi-material printing is an important development direction of metal additive manufacturing at present,the use of multi-material printing technology can save materials,give full play to the coupling design characteristics of materials and structures,and achieve comprehensive excellent performance or function.Laser in situ alloying technology is one of the core methods to realize multi-material printing,using laser as a heat source to melt powder layer by layer to form three-dimensional parts,the formed metal parts have high density,high dimensional accuracy and good surface roughness.Due to the high vapor pressure of Mn element,the evaporation effect is more intense under the action of high temperature heat source.Aiming at the element evaporation problem in the preparation technology of multi-material laser in-situ alloying,pure metal powder Fe and Mn are used as raw materials,and high flux additive manufacturing equipment is adopted.Laser selective melting tests of Fe10Mn and Fe20Mn mixed heterogeneous powders were carried out,and the effects of different laser power,scanning speed,composition ratio and other param‐eters on the mass loss and composition accuracy of formed samples were analyzed.The results show that the quality loss rate of 20%manganese content is lower than that of 10%manganese content.The sample with high Mn content has more intense evaporation,higher recoil pressure and narrower and deeper melt pool during forming.When the laser power is 220 W,the scanning speed is 500 mm/s,the scanning spacing is 0.08 mm,the layer thickness is 0.03 mm,the parameters of in-situ laser alloying alloy forming are the best.And the density of formed samples can up to 7.81 g/cm^(3),the density up to 99.78%.The mass loss rate of in-situ alloyed Fe20Mn alloy is only 1.50%under the optimum process parameters.Therefore,Mn has a greater tendency to evaporate in Fe-Mn alloys than Fe.The lasercision control of evaporative elements.