摘要
基于电弧增材制造(Wire arc additive manufacturing,WAAM)技术,以NiTi丝(Ni 50.50 at.%)为堆积材料制造形状记忆合金薄壁构件,研究其组织成分、相变特征和力学性能。结果表明,由于不同的热循环条件,沿试样高度方向上每道沉积层微观结构不同,第一沉积层为较大的等轴晶,随着热量累积,晶粒生长趋向为更细小的等轴形态,层间为柱状晶。室温下,试样是奥氏体相(Ni51.10at.%),与丝材相比,电弧增材制造的构件硬度较高且具有更宽的温度变化范围和相变滞后现象。试样拉伸强度约为611.30MPa,延伸率约为19.50%,具有较好的断裂韧性。试样在第一次加载-卸载循环时塑性应变仅为1.01%,8个循环后塑性应变趋于稳定,约为2.68%。
Wire arc additive manufacturing(WAAM)is used for fabrication of NiTi parts using a dedicated Ni-rich(50.50 at.%)NiTi wire as the feedstock material.The microstructure,phase transformation characteristics and mechanical properties of the as-built parts are investigated.Experimental results show that the microstructure in each deposition layer is different as a result of the different thermal cycle conditions.Along the part height,the first deposited layer is larger equiaxed grains.As the heat input gradually accumulates,the grain growth tends to the finer equiaxed form,and there are columnar grains between two deposited layers.The as-built parts are completely austenite phase at room temperature.The Ni content of deposited layers which have higher hardness,wider transformational range and hysteresis compared to the as-received NiTi wire is 51.10 at.%.The tensile strenght of the as-built parts is of about 611.30 MPa with a corresponding fracture strain of 19.50%.The fracture surface with dimple fracture had good ductility.Additionally,it can be seen that the WAAM specimens exhibit good superelastic properties,evidenced by a low irrecoverable strain of 1.01%upon unloading in the first cycle.The plastic strain increases during the first 8 cycles,and reaches near a constant value of 2.68%.
作者
葛福国
彭倍
柯文超
敖三三
从保强
祁泽武
曾志
GE Fuguo;PENG Bei;KE Wenchao;AO Sansan;CONG Baoqiang;QI Zewu;ZENG Zhi(School of Mechanical and Electrical Engineering,University of Electronic Science and Technology of China,Chengdu 611731;School of Material Science and Engineering,Tianjin University,Tianjin 300072;School of Mechanical Engineering and Automation,Beihang University,Beijing 100191)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2020年第8期99-106,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金(51775091)
四川省重点研发计划(2018GZ0284,2019YFG0339)资助项目。
关键词
电弧增材制造
NITI形状记忆合金
微观结构
相变特征
力学性能
wire arc additive manufacturing
NiTi shape memory alloy
microstructure
phase transformation
mechanical properties
作者简介
葛福国,男,1994年出生,博士研究生。主要研究方向为NiTi形状记忆合金的先进加工技术。E-mail:gfg18200141721@163.com;通信作者:曾志,男,1982年出生,博士,教授,博士研究生导师。主要研究方向为焊接结构断裂与强度。E-mail:zhizeng@uestc.edu.cn。
