A Study of Microstructure Evolution During Creep of 9Cr-1Mo Steel Using Ultrasonic and Hardness Measurements
A Study of Microstructure Evolution During Creep of 9Cr-1Mo Steel Using Ultrasonic and Hardness Measurements
复制标题
DOI：
10.1007/s11665-019-03987-3
复制
发表时间：
2019-04
影响因子：
2.3
通讯作者：
Lin Zhu;Xinbao Liu;P. Fan;Jianqiu Liu
中科院分区：
文献类型：
--
作者：
Lin Zhu;Xinbao Liu;P. Fan;Jianqiu Liu
在这项工作中，显微组织的变化，在蠕变过程中的9 Cr-1 Mo钢的特点是使用超声波和硬度测量。首先在873 K下分别在160和175 MPa的初始应力下进行该钢的蠕变试验。然后，在每个应力水平下制备8个试样，通过中断试验来模拟各种蠕变状态。随后，通过超声波检测引入了超声衰减和声速两个参数。实验结果表明，无论应力大小，超声衰减在蠕变断裂时间的20%左右出现一个峰值，在50%左右出现一个最小值，表明超声衰减与蠕变寿命分数有很强的相关性。除了在初级蠕变期间略有增加之外，在三级蠕变期间超声速度表现出显著的变化。通过对微观组织变化的分析，发现超声衰减对位错的动态变化具有显著的敏感性。相反，速度主要与沉淀物的演化有关。维氏硬度在蠕变过程中呈单调下降趋势，在二次和三次蠕变过程中，维氏硬度与M23 C6碳化物平均直径的倒数呈线性关系。因此，这表明，目前的超声波和硬度测量提供了一个方便的工具，以评估组织演变过程中的蠕变退化的耐热钢。
In this work, microstructural changes during creep of 9Cr-1Mo steel were characterized using ultrasonic and hardness measurements. The creep testing of this steel was firstly performed at 873 K under the initial stresses of 160 and 175 MPa, respectively. Then, eight specimens under each stress level were prepared by the interrupted tests to simulate various creep states. Subsequently, two parameters of ultrasonic attenuation and velocity were introduced by the ultrasonic testing. Experiment results showed that regardless of the stresses, the ultrasonic attenuation experiences a peak at about 20% of the creep rupture time and a minimum value at about 50%, showing a strong correlation between ultrasonic attenuation and the creep life fraction. In addition to a slight increase during the primary creep, the ultrasonic velocity exhibits a significant change during the tertiary creep. Based on the analysis of microstructure changes, it indicated that the ultrasonic attenuation is significantly sensitive to the dynamic changes of the dislocation. In contrast, the velocity is mainly related to the evolution of precipitates. The Vickers hardness decreases monotonously during the creep process and presents a linear relation with the inverse of average diameter of M23C6carbides during the secondary and tertiary creep. Accordingly, it suggested that the present ultrasonic and hardness measurements provided a convenient tool to evaluate the microstructure evolution during creep degradation of heat-resistant steels.