如何获得钎焊接头三明治微结构的蠕变力学性能一直以来是一个难题. 文中基于Wen-Tu蠕变延性耗竭模型开发了钎焊接头蠕变损伤子程序，利用ABAQUS有限元软件建立了与SOFC密封接头相类似的钎焊接头小冲杆模型；采用试验与有限元相结合的方法研究了以304不锈钢为母材的SOFC钎焊接头蠕变损伤特性，得到了不同载荷下钎焊接头试样中心蠕变挠度变化率和蠕变应变变化率之间关系，阐明了钎焊接头在小冲杆蠕变试验条件下的蠕变损伤及裂纹扩展规律. 结果表明，适当的增加钎料的厚度有利于提高钎焊接头的抗蠕变变形能力，延长高温蠕变断裂寿命，且钎焊接头在多轴应力作用下主要断裂方式为脆性断裂. 初始裂纹最早在母材下表面萌生，距试样中心0.85 mm处，随后向上扩展至钎料层下表面，然后在钎料层上表面出现裂纹逐渐向母材上表面与钎料层下表面扩展，直至断裂.
Obtaining the creep properties of sandwich structure of brazed joint has always been a challenge. Based on Wen-Tu creep-ductility exhaustion model, a subroutine for creep damage evolution of braze sealant of solid oxide fuel cell (SOFC) was developed in the finite element model of small punch test (SPT) using ABAQUS software. The evolution and characteristics of creep damage of the brazed joint with 304 stainless steel as base metal were studied by combining experiment and finite element analysis. The relationship between the change rate of central creep deflection and the creep strain rate of the brazed joint under different loads was obtained. The evolution of creep damage and crack propagation of brazed joint in the small punch creep test is clarified. The results show that the main fracture mode of brazed joint under multiaxial stress is brittle fracture, and the creep crack originates at the lower surface of base metal, which is 0.85 mm far away from the center of SPT specimen, and gradually propagates to the upper surface of base metal and the lower surface of the solder layer until fractures.
[1] 蒋文春, 张玉财, 关学伟. 平板式SOFC钎焊自适应密封热应力与变形分析[J]. 焊接学报, 2012, 33(11): 55-58
Jiang Wenchun, Zhang Yucai, Guan Xuewei. Thermal stress and deformation in bonded compliant seal design for planar SOFC[J]. Transactions of the China Welding Institution, 2012, 33(11): 55-58
[2] Stambouli A B, Traversa E. Solid oxide fuel cells (SOFCs): a review of an environmentally clean and efficient source of energy[J]. Renewable & Sustainable Energy Reviews, 2002, 6(5): 433-455.
[3] 李森. 中低温固体氧化物燃料电池阳极功能层及电解质薄膜制备[D]. 大连: 大连理工大学, 2019.
Li Sen. Fabrication of anode functional layer and thin film electrolyte for low-intermediate temperature solid oxide fuel cells[D]. Dalian: Dalian University of Technology, 2019.
[4] 陈家丽. 低温型固体氧化物燃料电池电解质的研究进展[J]. 山东化工, 2019, 48(17): 78-79
Chen Jiali. Research progress of electrolytes for low temperature solid oxide fuel cells[J]. Shandong Chemical Industry, 2019, 48(17): 78-79
[5] 刘泳良. 中温固体氧化物燃料电池密封材料的设计与性能研究[D]. 上海: 上海交通大学, 2013.
Liu Yongliang. Design and performance of sealing materials for IT-SOFC[D]. Shanghai: Shanghai Jiao Tong University, 2013.
[6] 陈建钧, 史进, 涂善东, 等. BNi-2/0Cr18Ni9钎焊接头高温蠕变行为的试验研究及数值模拟[J]. 焊接学报, 2006, 27(3): 43-47
Chen Jianjun, Shi Jin, Tu Shandong, et al. Experimental research and numerical simulation on creep behavior of BNi-2/0Cr18Ni9 brazed joint at high temperature[J]. Transactions of the China Welding Institution, 2006, 27(3): 43-47
[7] 宋明, 李旭阳, 曹宇光, 等. 基于BP神经网络与小冲杆试验确定在役管道钢弹塑性性能方法研究[J]. 力学学报, 2020, 52(1): 82-92
Song Ming, Li Xuyang, Cao Yuguang, et al. Determination of elastoplastic properties of in-service pipeline steel based on BP neural network and small punch test[J]. Chinese Journal of Theoretical and Applied Mechanics, 2020, 52(1): 82-92
[8] 盛晓茜, 洪军, 朱林波. 小冲杆蠕变测试技术的研究综述[J]. 压力容器, 2018, 35(10): 44-58
Sheng Xiaoxi, Hong Jun, Zhu Linbo. Review of research on small punch creep test[J]. Pressure Vessel Technology, 2018, 35(10): 44-58
[9] Kim J H, Ro U, Lee H, et al. A direct assessment of creep life based on small punch creep test[J]. Theoretical and Applied Fracture Mechanics, 2019, 104: 102346.
[10] Song K, Zhao L, Xu LY, et al. Experimental and numerical analysis of creep and damage behavior of P92 steel by small punch tests[J]. Theoretical and Applied Fracture Mechanics, 2019, 100: 181-190.
[11] Li Y Z, Ŝturm R. Determination of creep properties from small punch test[C]//ASME Pressure Vessels and Piping Conference. 2008: 739-750.
[12] 张玉财. 多轴应力状态下钎焊接头蠕变损伤与裂纹扩展研究[D]. 上海: 华东理工大学, 2016.
Zhang Yucai. Creep damage and crack growth analysis of the brazed joint under multi-axial stress state[D]. Shanghai: East China University of Science and Technology, 2016.
[13] Wen J F, Tu S T, Gao X L, et al. Simulations of creep crack growth in 316 stainless steel using a novel creep-damage model[J]. Engineering Fracture Mechanics, 2013, 98(1): 169-184.
[14] 温建锋. 基于应变的损伤力学模型及其在蠕变裂纹扩展数值模拟中的应用[D]. 上海: 华东理工大学, 2014.
Wen Jianfeng. Strain-based damage mechanics model and its application to numerical simulation of creep crack growth[D]. Shanghai: East China University of Science and Technology, 2014.
[15] 尤英俊. 小冲孔试样高温蠕变损伤的有限元模拟[D]. 南京: 南京工业大学, 2004.
You Yingjun. Finite element analysis of creep damage of in small punch test specimens at elevated temperature[D]. Nanjing: Nanjing Tech University, 2004.
[16] Saanouni K, Chaboche J L, Bathias C. On the creep crack growth prediction by a local approach[J]. Engineering Fracture Mechanics, 1986, 25(5): 677-691.
