摘要
γ'相强化镍基高温合金以其良好的高温组织与性能稳定性被广泛应用于航空航天、石油化工、汽车能源等领域,激光增材制造可满足现代工程领域对零部件内部结构优化与自身轻量化的要求,成为镍基高温合金复杂结构零部件制造与修复的新兴技术。然而,传统牌号的高强镍基高温合金的成分及强化机制与激光增材制造快速非平衡凝固及固态相变过程不适配,较宽的凝固温度区间和失衡的高温强韧性易引起微裂纹缺陷,难以保证合金的组织完整性和力学性能,严重制约了激光增材制造技术在高性能高温合金中的应用推广。基于此,本文综述了激光增材制造γ'相强化镍基高温合金裂纹的形成原因和影响因素,根据开裂机理从成分修正、成形工艺参数优化、后处理制度调控等方面总结了裂纹控制相关研究进展,探讨了当前能从根源上抑制裂纹的专用合金成分开发策略,并对激光增材制造γ'相强化镍基高温合金的未来发展方向进行了展望。
Significance Laser additive manufacturing technology merges design and production,incorporating crucial elements such as materials,structure,process,and performance.This integration offers an efficient and costeffective way to create prototypes and test new designs.It plays a vital role in manufacturing and repairing complex parts comprising nickelbased superalloys.However,this technology faces challenges with traditional highstrength nickelbased superalloys.The differences in composition and strengthening mechanisms,along with the rapid solidification and phase transitions unique to laser additive manufacturing,can lead to issues.The high alloying degree causes a wide solidification temperature range,while the abundance of intermetallic compounds leads to varying strength and ductility at high temperatures.This in turn increases the risk of microcrack defects.These defects can degrade the quality and mechanical properties ofγ′phase strengthened nickelbased superalloys produced through this method.Therefore,understanding the characteristics,formation mechanisms,and influencing factors of cracks,as well as recognizing the crack control methods and related achievements,can lay a theoretical foundation for exploring universal crack resistance pathway and composition design of superalloy matching additive forming characteristics.Progress This paper offers an indepth exploration of various crack types inγ′phase strengthened nickelbased superalloys used in laser additive manufacturing,including the morphology and mechanisms of solidification cracks(Fig.2),liquation cracks(Fig.3),ductilitydip cracks(Fig.5),and strain aging cracks(Fig.6).It elucidates the connections between the solid phase fraction and index for solidification cracking susceptibility,the differential scanning calorimetry curve and liquation sensitivity,the relationship between alloy ductility and the temperature range for ductility dip,as well as the link betweenγ′phase forming elements and the risk of strain aging cracking.The discussion includes common strategies for enhancing crack resistance,such as modifying the composition to alter solidification characteristics and minimize or eliminate the formation of lowmeltingpoint phases(Fig.8),introducing secondphase particles to encourage the shift from columnar to equiaxed crystal growth,thereby altering the residual stress state(Fig.9),and optimizing laser processing parameters to directly improve microstructure and forming quality(Fig.10).Furthermore,posttreatment methods significantly contribute to reducing cracking tendencies and enhancing the mechanical properties of superalloys.The ultimate approach to addressing the cracking issue involves developing nickelbased superalloys with specific compositions tailored for laser additive manufacturing.Recent successes in designing crackfree new alloys have leveraged tools such as thermodynamic calculations(Fig.11),machine learning(Fig.12),the cluster structure model(Fig.13 and Table 2),and the multiprinciple element concept(Fig.14).The shift from empirical to scientific and rational design in material research is being advanced by the use of phase diagram calculations for alloy design,supported by reliable thermodynamic databases.Machine learning facilitates the rapid development of mathematical models that quantitatively link material composition,processes,structure,and properties,enabling precise screening of target materials.The cluster structure model offers insights into how alloy elements’type and amount affect formability.Meanwhile,the multiprinciple element concept emerges as an efficient strategy for simultaneously enhancing crack resistance and the strength ductility balance.In summary,this paper’s overview of advancements in crack control and composition design forγ′phase strengthened nickelbased superalloys in laser additive manufacturing offers practical insights for the future creation of printable,hightemperature,highstrength nickelbased superalloys and their components(Fig.15).Conclusions and Prospects Significant progress has been made in controlling cracks inγ′phase strengthened nickelb superalloys for laser additive manufacturing, laying a theoretical and methodological foundation for creating crackfreesuperalloys through laser processing. Despite these advancements, developing precipitation strengthened nickelbased super alloys and their components that maintain highdensityforming, along with stable microstructure and performance in hightemperatureenvironments, remains challenging. Future research should focus on several key areas. First, it is crucial to understand the fundamental differences in cracking mechanisms between different alloys. Establishing a clear link between the types and contents of γ′ strengthening elements, their interactions, and their impact on crack sensitivity will aid in developing universal crack prevention and control strategies for similar alloys. Second, it is vital to develop swift design criteria for alloy compositions that align with desired performance and printability, establishing a distinct system of γ′ phase strengthened nickelbasedsuperalloys tailored for laser additive manufacturing. Third, enhancing the understanding of the alloys’ resistance to creep, fatigue, corrosion, thermal shocks, and the longterm stability of their microstructure and performance at high temperatures will further promote their adoption in critical sectors such as aerospace and nuclear power, among others. Finally, achieving mold-free manufacturing of crack-free nickel-based single crystal superalloys with superior overall performance, alongside the production of large, precise, and complex structural components, is essential. This advancement aims to fulfill the demanding conditions of aircraft engines operating at higher temperatures and in more severe environments.
作者
史淑静
李卓
杨晨
曾子恒
程序
汤海波
王华明
Shi Shujing;Li Zhuo;Yang Chen;Zeng Ziheng;Cheng Xu;Tang Haibo;Wang Huaming(Ningbo Institute of Technology,Beihang University,Ningbo 315800,Zhejiang,China;National Engineering Laboratory of Additive Manufacturing for Large Metallic Components,Beihang University,Beijing 100191,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2024年第10期3-24,共22页
Chinese Journal of Lasers
基金
国家重点研发计划(2023YFB4603304,2023YFB4603300,2018YFB0703400)
国家自然科学基金(51905023,52090044)
国家科技重大专项(Y2019-VII-0011-0151)。
关键词
激光技术
增材制造
高温合金
裂纹
优化与设计
laser technique
additive manufacturing
superalloys
crack
optimization and design
