Experimental investigation of the effects of super-elasticity on the machinability of NiTi alloys
Experimental investigation of the effects of super-elasticity on the machinability of NiTi alloys
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DOI：
10.1007/s00170-021-07166-4
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
Hao Yang;Katsuhiko Sakai;H. Shizuka;Yuji Kurebayashi;K. Hayakawa;T. Nagare
中科院分区：
文献类型：
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作者：
Hao Yang;Katsuhiko Sakai;H. Shizuka;Yuji Kurebayashi;K. Hayakawa;T. Nagare
由于NiTi合金固有的材料特性和独特的相变行为，其加工是一项具有挑战性的任务。在这项研究中，超弹性对室温奥氏体NiTi合金的切削加工性能的影响进行了研究，通过在不同的切削速度下的非预热和预热条件下进行车削实验。结果，工件表现出不可避免的超弹性形状恢复，并经历部分相变，因为在非预热条件下加工期间工件的温度没有超过马氏体终止温度（Md）。工件的超弹性恢复导致可加工性的恶化，通过尺寸精度的降低，切削阻力的增加，和刀具寿命的缩短。超弹性引起的切削加工性能的恶化随着切削速度的增加而加剧。然而，过低的切削速度10米/分钟诱导严重的堆积边缘沉积在加工表面上。当工件预热到Md以上时，由于消除了超弹性的影响，提高了尺寸精度，降低了切削阻力，延长了刀具寿命。因此，在将工件预热到Md以上的温度后，以25至50 m/min范围内的中等切削速度进行加工可以改善室温奥氏体NiTi合金的可加工性。
Machining of NiTi alloys is a challenging task owing to their inherent material properties and unique phase transformation-based behaviors. In this study, the effects of super-elasticity on the machinability of room-temperature austenitic NiTi alloy were investigated through turning experiments conducted at various cutting speeds under the non-preheating and preheating conditions. As a result, the workpiece exhibited an unavoidable super-elastic shape recovery and underwent a partial phase transformation because the temperature of the workpiece had not exceeded the martensite desist temperature (Md) during machining under the non-preheating condition. The super-elastic recovery of the workpiece resulted in the deterioration of the machinability, through the decrease in the dimension accuracy, increase in the cutting resistance, and shortening of the tool life. The deterioration of the machinability caused by super-elasticity was intensified with the increase in the cutting speed. However, an excessively low cutting speed of 10 m/min induced severe built-up edge deposition on the machined surface. When the workpiece was preheated to a temperature above theMd, the dimension accuracy was enhanced, the cutting resistance decreased and the tool life was prolonged owing to the elimination of the effects of the super-elasticity. Therefore, machining at moderate cutting speeds in the range of 25 to 50 m/min after preheating the workpiece to a temperature above theMdcan improves the machinability of room-temperature austenitic NiTi alloy.