机械振动辅助激光增材制造In625合金的微观组织及力学性能研究

RESEARCH ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF IN625 ALLOY FABRICATED BY ADDITIVE MANUFACTURING WITH MECHANICAL VIBRATION

叶国威

11849312

硕士

电子与通信工程领域工程

刘正白

2020-06-02

2020-07-20

哈尔滨工业大学

深圳

激光增材制造技术作为一种典型的快速成型方法，可以净成形制造高性能 复杂金属零部件，具有设计制造周期短，无需型腔刀具、制造过程可控性高等 诸多优点，已经被广泛应用航空航天，海洋，医疗，石油化工和模具等诸多行 业。激光增材制造是一个多物理场耦合的复杂微冶金过程。其凝固组织对工艺 参数的依赖具有不确定性。极为复杂的材料冶金过程依然不十分明确。目前依 然缺乏有效的手段对增材构件微观组织和力学性能实现精确控制。为了实现对 增材制造组织和性能更高自由度的控制，新的有效调控激光增材制造过程的方 法亟需开发。 本文以常用的金属材料 In625 高温合金作为实验原材料。通过在激光增材 制造过程中施加机械振动，来研究机械振动频率和振幅对激光增材制造凝固组 织及其力学性能的影响机理，从而为机械振动辅助控制激光增材制造构件组织 和性能提供基础研究。主要研究工作分为以下几个方面： 采用外加垂直机械振动辅助激光增材制造 In625 高温合金。通过激光共聚 焦显微镜、光学显微镜等手段表征分析不同机械振动参数下激光直接沉积 In625 高温合金构件的宏观形貌和微观组织。研究结果表明，激光增材制造微熔池凝 固行为受到机械振动的影响。随着机械振动频率的增加，竖直取向生长的定向 晶受到抑制，并逐步转变为倾斜生长的细小枝晶。而机械振动幅度的变化对晶 体生长方向能够起到一定程度的调节作用。同时，机械振动有助于使得合金试 样表面形貌平整。 对激光增材制造的 In625 合金试样进行切割，表面打磨，制备出拉伸试样， 研究辅助机械振动对 In625 高温合金凝固组织力学性能(拉伸性能、硬度)的影响 规律。研究结果表明，随着机械振动频率的增大，In625 高温合金的硬度、屈服 强度以及延伸率都呈先增大后下降的趋势。当机械振动频率为 100 Hz 时，其硬 度、屈服强度和延伸率都达到了最大。随着机械振动幅度的增大，In625 高温合 金的硬度则呈下降的趋势，而屈服强度和延伸率呈下降趋势。当以激光增材制 造 In625合金抗拉强度作为评定标准时，最佳的机械振动参数为：频率为 100 Hz， 幅度为 0.25 mm。 对激光增材制造 In625 合金进行固溶热处理，研究不同固溶热处理温度与 机械振动耦合作用下对 In625 的力学性能的影响。研究结果表明，随着固溶温 度升高 In625 高温合金的硬度呈下降趋势。随着固溶温度的升高，In625 高温合金的抗拉强度呈先增加后下降趋势，在 850 ℃时，其抗拉强度达到最高，对比 沉积态下提升了 4.88 %。随着固溶温度升高，In625 合金的延伸率逐步增加， 在 1050 ℃时，相比比沉积态下，提高了 26.67 %。随着固溶温度升高，In625 合金的屈服强度呈下降趋势。 本文通过研究机械振动辅助激光增材制造 In625 合金，表明外加机械振动 是一种有效的调控激光增材制造凝固组织和力学性能的方法。通过合理的匹配 机械振动参数和激光增材制造参数，可以一定程度上细化凝固组织晶粒，提高 凝固组织的拉伸力学性能。该研究成果有助于促进激光增材制造形-性一体化调 控技术的发展。

As a typical rapid prototyping method, laser additive manufacturing technology can shape and manufacture high-performance complex metal parts. It has many advantages such as short design and manufacturing cycle, no need for cavity tools, and high controllability of the manufacturing process. It has been widely used. Aerospace, marine, medical, petrochemical and mold industries. Laser additive manufacturing is a complex micro-metallurgical process with multiple physical couplings. The dependence of its solidified structure on process parameters is uncertain. The extremely complex material metallurgical process is still not very clear. At present, there is still no effective method to accurately control the microstructure and mechanical properties of additive components. In order to achieve a higher degree of freedom in the control of additive manufacturing organization and performance, new methods for effectively regulating the laser additive manufacturing process are urgently needed to be developed. In this paper, the commonly used metal material In625 is a new type of rapid manufacturing method. Its principle is to use a high-energy laser beam to melt the metal powder at high temperature. The laser beam moves according to the path set on the computer software, and then bottom On the other hand, three-dimensional parts with complex shapes are formed. In625 superalloy is a commonly used metal material for experimental raw materials. By applying mechanical vibration in the process of laser additive manufacturing, the mechanism of the effect of mechanical vibration frequency and amplitude on the solidification structure and mechanical properties of laser additive manufacturing is studied, so as to provide a basis for mechanical vibration to assist in controlling the structure and performance of laser additive manufacturing components the study. The main research work is divided into the following aspects: In addition, the vertical mechanical vibration assisted laser additive is used to manufacture In625 superalloy. The macroscopic morphology and microstructure of In625 superalloy directly deposited by laser under different mechanical vibration parameters were characterized and analyzed by means of laser confocal microscope and optical microscope. The results show that the solidification behavior of the micro-melt pool produced by laser additive manufacturing is affected by mechanical vibration. With the increase of mechanical vibration frequency, the directional crystals grown in vertical orientation are suppressed and gradually transformed into small grown obliquely. The change of mechanical vibration amplitude can regulate the crystal growth direction to a certain extent. At the same time, mechanical vibration helps to make the surface of the alloy sample smooth. The In625 superalloy sample manufactured by laser additive was cut and the surface was polished to prepare a tensile sample. The influence of auxiliary mechanical vibration on the mechanical properties (tensile properties and hardness) of the solidified structure of In625 superalloy was studied. The research results show that with the increase of mechanical vibration frequency, the hardness, yield strength and elongation of In625 superalloys tend to increase and then decrease. When the mechanical vibration frequency is 100 Hz, its hardness, yield strength and elongation have reached their maximum. With the increase of the amplitude of mechanical vibration, the hardness of In625 superalloy showed a downward trend, while the yield strength and elongation showed a downward trend. When the tensile mechanical properties of In625 alloy manufactured by laser additive are used as the evaluation standard, the best mechanical vibration parameters are: frequency 100 Hz, amplitude 0.25 mm. The solution heat treatment of In625 alloy manufactured by laser additive manufacturing was conducted to study the effect of different solution heat treatment temperature and mechanical vibration on the mechanical properties of In625. The research results show that the hardness of In625 superalloy decreases with increasing solid solution temperature. With the increase of solution temperature, the tensile strength of In625 superalloy increased first and then decreased. At 850 ℃, its tensile strength reached the highest level, which increased by 4.88% compared with the deposited state. As the solution temperature increases, the elongation of the In625 alloy gradually increases. At 1050℃, it is 26.67% higher than that in the as-deposited state. As the solution temperature increases, the yield strength of In625 alloy tends to decrease. In this paper, by studying mechanical vibration assisted laser additive manufacturing of In625 superalloy, it is shown that the application of mechanical vibration is an effective method to adjust the solidification structure and mechanical properties of laser additive manufacturing. By reasonably matching the mechanical vibration parameters and laser additive manufacturing parameters, the grains of the solidified structure can be refined to a certain extent, and the tensile mechanical properties of the solidified structure can be improved. The research results help to promote the development of laser additive manufacturing shape-shape integrated control technology.

激光增材制造 机械振动 力学性能 微观组织 高温合金

laser additive manufacturing mechanical vibration mechanical

中文

联合培养

南方科技大学

叶国威. 机械振动辅助激光增材制造In625合金的微观组织及力学性能研究[D]. 深圳. 哈尔滨工业大学,2020.