水冷下Ti-6Al-4V钛合金热模拟试样组织研究

Research on microstructure of Ti-6Al-4V titanium alloy by thermal simulation under water cooling

采用Gleeble3500热模拟试验机对Ti-6Al-4V钛合金进行了焊接热模拟试验,模拟该合金自高温β相区以一定冷却速率冷却的过程。试样选用两端钻孔的标准焊接模拟试样,均温区约2 mm宽。采用金相显微镜、扫描电镜和X射线衍射分析研究了试样不同区域的显微组织与结构。热模拟区边缘区域为细小的片状α组织,中心均温区域为针状α′马氏体组织;XRD标定发现母材和热模拟区域的衍射峰分别与纯钛密排六方α和α′相偏移一个角度后重合;热模拟区域的显微硬度略高于母材。

Microstructure of welded Ti-6Al-4V titanium alloy was investigated by means of welding thermal simulation technique on a Gleeble3500 thermal simulation testing machine.The thermal simulation samples were drilled at its both ends with the isothermal region of about 2 mm width.Microstructure and phases were observed by optical microscope,scanning electron microscopy and X-ray diffraction analysis in different regions of the samples.Fine lamellar α phase at the edge region and acicular α′ martensite at the center region of the thermal simulation sample are observed.XRD analysis indicates the diffraction peaks of the hexagonal close packed（hcp） crystal α and α′ phase offset a small angle between the base metal and the sample.The microhardness of the thermal simulation sample is slightly higher than that of the base metal.