Thermomechanically influenced dynamic elastic constants of laser powder bed fusion additively manufactured Ti6Al4V
Thermomechanically influenced dynamic elastic constants of laser powder bed fusion additively manufactured Ti6Al4V
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DOI：
10.1016/j.msea.2021.140990
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发表时间：
2021-03-13
期刊：
影响因子：
6.4
通讯作者：
Dahotre, Narendra B.
中科院分区：
文献类型：
--
作者：
Pantawane, Mangesh, V;Yang, Teng;Dahotre, Narendra B.
本文报道了激光粉末床熔融增材制造的Ti6Al4V合金的动态弹性常数，最近开发的有效体积模量弹性成像技术，并将它们与静态弹性常数使用纳米压痕技术评估。利用这种弹性成像技术，采用两种超声频率（10 MHz和20 MHz），其在增材制造的Ti6Al4V中清楚地识别出空间变化的动态弹性常数和有效密度，同时与锻造的Ti6Al4V进行比较。在20 MHz超声频率下，扫描区域的弹性常数和有效密度的空间分辨率显著提高。动态弹性常数为5%？比增材制造的Ti6Al4V和锻造的Ti6Al4V获得的静态弹性常数低8%。此外，本研究还比较了增材制造的Ti6Al4V、锻造Ti6Al4V以及固溶和水淬锻造Ti6Al4V的弹性模量。使用扫描电子显微镜对增材制造的Ti6Al4V的显微组织检查显示，与水淬锻造的Ti6Al4V中几乎没有孪晶的马氏体板条相反，马氏体板条内存在高密度的内部孪晶。这样高的缺陷密度的起源是实现了由热机械计算模型，预测迅速变化的交变拉压应力在49？720 MPa，这反过来又影响了动态和静态弹性常数。
This paper reports the dynamic elastic constants of laser powder bed fusion additively manufactured Ti6Al4V alloy by recently developed effective bulk modulus elastography technique and compares them with the static elastic constants evaluated using the nanoindentation technique. With this elastography technique, two ultrasound frequencies (10 MHz and 20 MHz) were employed, which distinctly identified spatially varying the dynamic elastic constants and effective density in additively manufactured Ti6Al4V while comparing to the wrought Ti6Al4V. The spatial resolution of elastic constants and effective density of the scanned region significantly improved at 20 MHz ultrasound frequency. The dynamic elastic constants were 5%?8% lower than static elastic constants obtained for the additively manufactured Ti6Al4V and wrought Ti6Al4V. In addition, the present study compares the elastic moduli of additively manufactured Ti6Al4V, wrought Ti6Al4V, and solutionized and water quenched wrought Ti6Al4V. The microstructural examination of additively manufactured Ti6Al4V using scanning electron microscopy revealed a high density of internal twins within martensite laths contrary to scarcely twinned martensite lath in water quenched wrought Ti6Al4V. The origin of such high defect density was realized by a thermo-mechanical computational model that predicted rapidly changing alternating tensile-compressive stresses in the range of 49?720 MPa that, in turn, affected the dynamic and static elastic constants.