Ter Haar Gerrit M, Becker Thorsten H
Materials Engineering Group, Department of Mechanical & Mechatronic Engineering, University of Stellenbosch, Stellenbosch 7600, South Africa.
Materials (Basel). 2018 Jan 17;11(1):146. doi: 10.3390/ma11010146.
Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α'/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.
当前应用于选择性激光熔化制备的Ti-6Al-4V的后处理热处理无法获得与热机械加工锻造Ti-6Al-4V相同的微观结构，因此也无法获得其优异的拉伸性能。由于工业界对选择性激光熔化制备的零件需求不断增长，目前正在进行旨在改善机械性能的研发工作。本研究旨在开发后处理退火策略，以改善选择性激光熔化制备的Ti-6Al-4V零件的拉伸性能。利用光学显微镜和电子显微镜研究了α晶粒形态与退火温度、保温时间和冷却速率之间的关系。采用准静态单轴拉伸试验来测量不同退火零件的拉伸性能。研究发现，通过采用高温退火策略，拉长的α'/α晶粒可破碎成等轴晶粒。结果表明，双峰微观结构比目前经过热处理的选择性激光熔化制备的Ti-6Al-4V样品具有更优异的拉伸延展性。
