Attanasio Aldo, Gelfi Marcello, Pola Annalisa, Ceretti Elisabetta, Giardini Claudio
Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, Brescia 25123, Italy.
Department of Engineering, University of Bergamo, Via Marconi 5, Dalmine (BG) 24044, Italy.
Materials (Basel). 2013 Sep 24;6(9):4268-4283. doi: 10.3390/ma6094268.
In the most recent decades the introduction of unconventional machining processes allowed the development of micromachining techniques. In this work, the influence of material microstructures on the micromilling process was investigated. Ti6Al4V alloy was selected as workpiece material since it is a very common material for micro applications and because its duplex microstructure can be easily changed by proper thermal treatments. Four different microstructures (namely bimodal, fully equiaxed, fully lamellar and mill annealed) were obtained through recrystallization annealing treatments carried out at different times and temperatures. The mechanical properties of the samples were assessed by microhardness measurements. Nano-indentations were also performed on single grains to understand how the different hardness of phases and structures present in the Ti6Al4V alloy can affect the micromilling process. Microchannels using two flute flat end mills with a diameter equal to 200 µm were realized on the treated samples. Two different feed-per-tooth values were used during the tests. Cutting force, channel shape and burr dimension were investigated. Morphological and energy dispersive spectroscopy (EDS) analyses were performed on tools by means of a scanning electron microscope (SEM): in this way the phenomena mainly influencing the tool status were also identified. Lower cutting forces and reduced tool wear were observed when working fully lamellar microstructures compared to the other ones.
在最近几十年里，非常规加工工艺的引入推动了微加工技术的发展。在这项工作中，研究了材料微观结构对微铣削工艺的影响。选择Ti6Al4V合金作为工件材料，因为它是微应用中非常常见的材料，并且其双相微观结构可以通过适当的热处理轻松改变。通过在不同时间和温度下进行再结晶退火处理，获得了四种不同的微观结构（即双峰、完全等轴、完全片状和轧制退火）。通过显微硬度测量评估样品的力学性能。还对单个晶粒进行了纳米压痕测试，以了解Ti6Al4V合金中不同相和结构的硬度如何影响微铣削工艺。在处理后的样品上使用直径为200 µm的两刃平底铣刀加工微通道。测试过程中使用了两种不同的每齿进给量。研究了切削力、通道形状和毛刺尺寸。通过扫描电子显微镜（SEM）对刀具进行了形态学和能量色散光谱（EDS）分析：通过这种方式，还确定了主要影响刀具状态的现象。与其他微观结构相比，在完全片状微观结构上加工时观察到较低的切削力和较少的刀具磨损。
