基于选区激光熔化成型的掺铝IN718镍基高温合金制备技术研究

RESEARCH ON THE PREPARING METHODOLOGY OF A NOVEL IN718 ALLOY WITH ADDITIVE ALUMINIUM BASED ON THE SELECTIVE LASER MELTING TECHNOLOGY

张则焕

11649109

硕士

材料学

严明

2018-05-27

2018-06-19

哈尔滨工业大学

深圳

本文采用机械混粉的方式在 IN718 粉末中添加铝粉，利用选区激光熔化技术（Selective Laser Melting）所用粉末较为细小，凝固速度快且成形过程中有很强搅拌作用的特点，不经过预合金化而通过选区激光熔化技术改变 IN718 中铝含量制备新型的高温合金。对制备的及热处理后的新型高温合金，进行组织性能分析。利用三维混合机将粉末进行混合，在 IN718 粉末中添加不同量的铝粉。利用激光粒度分析仪、粉体综合测试仪、扫描电子显微镜等对混合粉末进行特性分析，并通过选区激光熔化技术进行合金制备。对不同工艺成形的新型合金利用密度天平进行密度测试，发现随着激光功率、扫描速度的增加致密度都是先增大后减小，同时都在激光功率 200 W，扫描速度 900 mm/s 有最大的致密度，相对密度在 99.4%以上。用万能力学试验机对 SLM 成形制备的新型合金进行力学性能测试。考察了SLM 成型掺铝 IN718 粉末激光扫描速度的影响，随着扫描速度的增加抗拉强度变化很小，延伸率呈先增加后减小的趋势，最优参数为 900 mm/s。试验表明随着铝含量的增加，新制备合金抗拉强度升高，塑性下降。用 EDS 对 SLM 成形制备的合金进行 Al 元素分布均匀性检测。通过金相、扫描电子显微镜等手段研究掺铝IN718 不同铝含量的相及组织特征。SLM 成形制备的合金晶粒在 10 μm 都由非常细小的胞晶及柱晶组成随着掺铝量的增加，Laves 相含量增多。对制备的新合金分别进行了标准热处理、高强热处理及特殊热处理。随着 Al含量的增加，抗拉强度增加，塑性下降。高强处理有较大的抗拉强度但塑性较差，特殊热处理有较好的塑性。标准热处理及特殊热处理 IN718 合金与 IN718 + 0.5Al合金具有非常相近的性能。IN718 + 1Al 合金经过特殊热处理后抗拉强度达到1607MPa，延伸率 9.9%。使用扫描电子显微镜对制备的新型合金进行组织观察，δ、γ′、γ″随着掺 Al 含量不同、热处理制度不同其含量其形貌有很大变化。对标准热处理的合金进行 680 ℃/100 h 时效处理，合金 IN718 + 0.5Al 也就是 Al 质量分数在1.03%组织具有最好的热稳定性。

In this paper, aluminum powder is added to IN718 powder by mechanical mixing, and the powder is fine, fast solidification and strong stirring in the process of Selective Laser Melting, and a new type of superalloy is prepared by laser melting without pre alloying. The microstructure and properties of the prepared and heat-treated new superalloys were analyzed. The powder is mixed with three dimensional mixer, and the powder is added with different amount of aluminum powder. The characteristics of the mixed powder are analyzed by laser particle size analyzer, powder comprehensive tester, scanning electron microscope and so on, and the alloy is prepared by the laser melting technique of the IN718. The density measurement of the new alloys with different processes was carried out. It was found that the density of laser power and scanning speed increased first and then decreased with the increase of laser power and scanning speed. At the same time, the laser power was 200W, and the scanning speed 900 mm/s had the maximum density, and the relative density was over 99.4%.The mechanical properties of the new alloy prepared by SLM forming were tested by the universal mechanical test machine. The effect of laser scanning speed of aluminum doped IN718 powder in SLM molding was investigated. With the increase of the scanning speed, the tensile strength changed little, the elongation at first increased and then decreased, and the optimum parameter was 900 mm/s. The experimental results show that with the increase of aluminum content, the tensile strength and the ductility of the new alloy increase. The distribution uniformity of Al elements in SLM formed alloy was detected by EDS. Metallographic and scanning electron microscopy were used to study the phase and microstructure characteristics of Al doped IN718. The alloy grain formed by SLM is composed of very fine cell and columnar grains at 10 m, and the content of Laves phase increases with the increase of Al content.Standard heat treatment, high strength heat treatment and special heat treatment were carried out on the new alloys. With the increase of Al content, tensile strength increases and plasticity decreases. High strength treatment has greater tensile strength but poor plasticity, and special heat treatment has better plasticity. Standard heat treatment and special heat treatment of IN718 alloy and IN718 + 0.5Al alloy have very similar properties. The tensile strength of IN718 + 1Al alloy reaches 1607MPa after special heat treatment, and the elongation is 9.9%. The microstructure of the new alloy prepared by scanning electron microscope (SEM) has been observed. The shape of delta, gamma, and gamma is very different with the content of Al and the content of the heat treatment system. The alloy treated with standard heat treatment was treated at 680 /100h for aging. The alloy IN718 + 0.5Al was also the best thermal stability of Al with 1.03% mass fraction.

选区激光熔化 合金制备 IN718 铝 组织性能 热处理

Selective Laser Melting SLM Alloy Preparation IN718 Aluminum Microstructure and Mechanical Properties Heat Treatment System

中文

联合培养

南方科技大学

张则焕. 基于选区激光熔化成型的掺铝IN718镍基高温合金制备技术研究[D]. 深圳. 哈尔滨工业大学,2018.