摘要
利用选区激光熔化(selective laser melting,SLM)制备IN625镍基高温合金,采用光学显微镜(OM)、扫描电镜(SEM)、热力学计算和力学性能测试等方法研究了SLM IN625合金在700℃长期热暴露过程中微观组织及力学性能的演变规律。结果表明,SLM制备态合金经过高温固溶处理后,原始的非平衡态组织完全消除,形成了均匀一致的再结晶组织。在长期热暴露过程中,未经固溶处理的制备态合金中的δ相优先在枝晶间形核,而固溶态合金中的δ相由晶界形核逐渐向晶内生长;同时,制备态合金中δ相形核率较高而粗化速率较小,且γ″相向δ相的转变速度更快,在热暴露1000 h时,整个晶粒内布满了致密的δ相,γ″相向δ相的转变基本完成,而固溶态合金中δ相主要聚集在晶界两侧,且晶内仍分布着大量的γ″相;Si元素的晶界偏聚使得制备态合金晶界处形成了大量Laves相,并造成了晶界附近δ相的贫化,而固溶态合金的晶界析出相主要以MC为主;经过长期热暴露后,两种状态合金的强度均逐渐增大,塑性逐渐降低,但由于制备态IN625合金中δ相的含量较高,故其抗拉强度和屈服强度明显高于固溶态,而延长率相对较低。
Objective With the rapid development of metal additive manufacturing technologies,the use of selective laser melting(SLM)technology to rapidly manufacture nickel-based superalloy components has made a major breakthrough,which has greatly improved the manufacturing efficiency of high-performance complex components in the aerospace field and promoted optimized and upgraded component structures.IN625 nickel-based superalloy is maturely used in the SLM technology.It has high high-temperature mechanical properties,good high-temperature corrosion resistance and high-temperature oxidation resistance.It is used in nuclear power,industrial gas turbines and key materials for hot-end components in aerospace and other fields.The unique microstructural characteristics of SLM IN625 alloys cause their solid-state phase transition characteristics under long-term high temperature conditions to be obviously different from traditional solid-state phase transitions.In this paper the evolution of the structures and properties of the SLM IN625 nickel-based superalloys during long-term thermal exposure at 700℃ are investigated with a view to revealing the evolution of the microstructures and mechanical properties of the additively manufactured nickel-based superalloys.Methods IN625 powder with chemical compositions shown in Table 1 is used.Samples with dimension of 20 mm×20 mm×200 mm are prepared by the EP-M250 SLM system in nitrogen atmosphere.The processing parameters are chosen as follows;laser power of 200 W,scanning speed of 1000 mm/s,hatch spacing of 17μm,layer thickness of 30μm,and spot diameter of 100μm.The scanning strategy involves rotation of 67° of the laser between two adjacent layers.All the samples for a mechanical property test are cut from the as-built samples using wire cutting machining as shown in Fig.1.The heat treatment schemes used in the experiment are listed in Table 2.In order to compare the influence of the non-equilibrium microstructure in the as-built alloys on the evolution of the aging microstruct
作者
宋振峰
高双
何博
兰亮
王江
侯介山
Song Zhenfeng;Gao Shuang;He Bo;Lan Liang;Wang Jiang;Hou Jieshan(Research Center of High-Temperature Alloy Precision Forming,School of Material Engineering,Shanghai University of Engineering Science,Shanghai 201620,China;State Key Laboratory of Advanced Special Steel,Shanghai University,Shanghai 200444,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,Liaoning,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第14期342-351,共10页
Chinese Journal of Lasers
基金
上海市科学技术委员会“扬帆计划”项目(19YF1417500)
上海市科学技术委员会基金项目(19DZ2270200)
上海市省部共建高品质特殊钢冶金与制备国家重点实验室开放课题(SKLSS2020-10)。
关键词
激光技术
选区激光熔化
镍基高温合金
长期热暴露
组织演变
力学性能
laser technique
selective laser melting
nickel-based superalloy
long-term exposure
microstructural evolution
mechanical properties
