工程科学学报，第40卷，第4期：461-468,2018年4月 Chinese Journal of Engineering,Vol.40,No.4:461-468,April 2018 DOI:10.13374/j.issn2095-9389.2018.04.009:http://journals.ustb.edu.cn 基于声发射监测的316LN不锈钢的疲劳损伤评价 张 进，柴孟瑜，项靖海，段权四 西安交通大学化学工程与技术学院，西安710049 ☒通信作者，E-mail:quanduan(@mail.xjtu.cd.cn 摘要疲劳裂纹的萌生与扩展容易导致压力容器及管道的严重疲劳失效.因此就设备的安全可靠性而言，非常有必要对疲 劳裂纹扩展过程进行监测，并对疲劳损伤程度进行评估.本文针对316LN不锈钢材料进行疲劳实验研究，利用直流电位法测 量实验中的裂纹长度，得到了材料的疲劳裂纹扩展曲线.利用声发射技术对疲劳裂纹扩展过程进行监测，通过声发射多参数 分析对疲劳损伤状态进行评价，同时建立了声发射参数与线弹性断裂力学参数之间的关系，并进行寿命预测.研究表明：声发 射能够对316LN不锈钢的疲劳裂纹损伤进行有效评估，声发射累积参数如累积计数、累积能量和累积幅值曲线上的转折点标 志着疲劳裂纹进入快速扩展阶段，这可以为工程人员提供失效预警：声发射波形和频谱分析表明，噪声信号的幅值较小且信 号持续时间较长，信号包含的频率成分比较复杂，而裂纹扩展信号是突发型信号，衰减较快，信号频率主要集中在80~170kHz 范围内：声发射计数率、能量率和幅值率与应力强度因子幅度以及疲劳裂纹扩展速率之间呈线性关系，裂纹长度预测结果与 实测值接近.本研究工作对于工程结构的疲劳失效预警和剩余寿命预测具有重要意义. 关键词316LN不锈钢：疲劳裂纹扩展；声发射：多参数分析：寿命预测 分类号TG142.33·1 Fatigue damage evaluation of 316LN stainless steel using acoustic emission monitoring ZHANG Jin,CHAI Meng-yu,XIANG Jing-hai,DUAN Quan School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an 710049,China Corresponding author,E-mail:quanduan@mail.xjtu.edu.cn ABSTRACT The initiation and growth of fatigue cracks usually lead to serious fatigue failure of steel structures such as pressure ves- sels and pipelines.Therefore,for the safety and reliability of engineering structures,monitoring the fatigue crack growth and evaluating the severity of fatigue damage are important.An investigation of fatigue damage evaluation of 316LN stainless steel was presented by using the in situ acoustic emission (AE)monitoring technique.Fatigue crack propagation tests of 3161N stainless steel were carried out.The direct-current potential-drop method was used to measure fatigue crack propagation.At the same time,the AE technique was used to monitor propagation of the fatigue cracks in real time.The fatigue damage of 316LN stainless steel was qualitatively assessed by AE multi-parametric analyses such as the AE count,energy,and amplitude.Moreover,the quantitative relationships among AE pa- rameters and the linear elastic fracture mechanics parameters were established for predicting the remaining fatigue life.The results show that the AE technique is effective for evaluating the severity of fatigue damage of 316LN stainless steel.The transition point on the curves of cumulated count,energy,and amplitude indicates that the fatigue crack propagates into the rapid crack propagation stage. This obvious change in AE could potentially provide failure warnings for researchers or engineers.Furthermore,the analyses of wave- form and frequency show that the noise signal with low amplitude and long duration contains complex frequency components,whereas the crack propagation signal is a type of burst signal and the frequency is mainly distributed in the range from 80 to 170 kHz.In addi- tion,the quantitative relations between fatigue crack propagation rate and AE rates such as the count rate,energy rate,and the ampli- tude rate were found to be linear,and these relations were used to predict fatigue crack length.The predicted fatigue crack lengths showed good agreement with the measured crack lengths.The results of the present investigation will be helpful for providing fatigue 收稿日期：2017-06-21工程科学学报，第 40 卷，第 4 期: 461--468，2018 年 4 月 Chinese Journal of Engineering，Vol． 40，No． 4: 461--468，April 2018 DOI: 10． 13374 /j． issn2095--9389． 2018． 04． 009; http: / /journals． ustb． edu． cn 基于声发射监测的 316LN 不锈钢的疲劳损伤评价 张 进，柴孟瑜，项靖海，段 权 西安交通大学化学工程与技术学院，西安 710049 通信作者，E-mail: quanduan@ mail． xjtu． edu． cn 摘 要 疲劳裂纹的萌生与扩展容易导致压力容器及管道的严重疲劳失效． 因此就设备的安全可靠性而言，非常有必要对疲 劳裂纹扩展过程进行监测，并对疲劳损伤程度进行评估． 本文针对 316LN 不锈钢材料进行疲劳实验研究，利用直流电位法测 量实验中的裂纹长度，得到了材料的疲劳裂纹扩展曲线． 利用声发射技术对疲劳裂纹扩展过程进行监测，通过声发射多参数 分析对疲劳损伤状态进行评价，同时建立了声发射参数与线弹性断裂力学参数之间的关系，并进行寿命预测． 研究表明: 声发 射能够对 316LN 不锈钢的疲劳裂纹损伤进行有效评估，声发射累积参数如累积计数、累积能量和累积幅值曲线上的转折点标 志着疲劳裂纹进入快速扩展阶段，这可以为工程人员提供失效预警; 声发射波形和频谱分析表明，噪声信号的幅值较小且信 号持续时间较长，信号包含的频率成分比较复杂，而裂纹扩展信号是突发型信号，衰减较快，信号频率主要集中在 80 ～ 170 kHz 范围内; 声发射计数率、能量率和幅值率与应力强度因子幅度以及疲劳裂纹扩展速率之间呈线性关系，裂纹长度预测结果与 实测值接近． 本研究工作对于工程结构的疲劳失效预警和剩余寿命预测具有重要意义． 关键词 316LN 不锈钢; 疲劳裂纹扩展; 声发射; 多参数分析; 寿命预测 分类号 TG142. 33 + 1 收稿日期: 2017--06--21 Fatigue damage evaluation of 316LN stainless steel using acoustic emission monitoring ZHANG Jin，CHAI Meng-yu，XIANG Jing-hai，DUAN Quan School of Chemical Engineering and Technology，Xi’an Jiaotong University，Xi’an 710049，China Corresponding author，E-mail: quanduan@ mail． xjtu． edu． cn ABSTＲACT The initiation and growth of fatigue cracks usually lead to serious fatigue failure of steel structures such as pressure ves￾sels and pipelines． Therefore，for the safety and reliability of engineering structures，monitoring the fatigue crack growth and evaluating the severity of fatigue damage are important． An investigation of fatigue damage evaluation of 316LN stainless steel was presented by using the in situ acoustic emission ( AE) monitoring technique． Fatigue crack propagation tests of 316LN stainless steel were carried out． The direct-current potential-drop method was used to measure fatigue crack propagation． At the same time，the AE technique was used to monitor propagation of the fatigue cracks in real time． The fatigue damage of 316LN stainless steel was qualitatively assessed by AE multi-parametric analyses such as the AE count，energy，and amplitude． Moreover，the quantitative relationships among AE pa￾rameters and the linear elastic fracture mechanics parameters were established for predicting the remaining fatigue life． The results show that the AE technique is effective for evaluating the severity of fatigue damage of 316LN stainless steel． The transition point on the curves of cumulated count，energy，and amplitude indicates that the fatigue crack propagates into the rapid crack propagation stage． This obvious change in AE could potentially provide failure warnings for researchers or engineers． Furthermore，the analyses of wave￾form and frequency show that the noise signal with low amplitude and long duration contains complex frequency components，whereas the crack propagation signal is a type of burst signal and the frequency is mainly distributed in the range from 80 to 170 kHz． In addi￾tion，the quantitative relations between fatigue crack propagation rate and AE rates such as the count rate，energy rate，and the ampli￾tude rate were found to be linear，and these relations were used to predict fatigue crack length． The predicted fatigue crack lengths showed good agreement with the measured crack lengths． The results of the present investigation will be helpful for providing fatigue