滕全全,汪 悦，有移亮,张 峥

(1 北京航空航天大学 材料科学与工程学院，北京100191；2 中国空间技术研究院，北京 100094)

充氢Cr-Mo钢变形过程的声发射特征

滕全全1,汪 悦2，有移亮1,张 峥1

(1 北京航空航天大学 材料科学与工程学院，北京100191；2 中国空间技术研究院，北京 100094)

对电化学充氢后的2.25Cr-1Mo钢进行拉伸实验，并在实时拉伸过程中采集声发射信号。结果表明：充氢后2.25Cr-1Mo钢抗拉强度为536.30MPa，下降约57MPa；断面收缩率为43.62%,下降约7%。拉伸断口上出现由氢脆引起的“白点”特征与准解理断裂形貌。充氢后试样拉伸过程弹性阶段的声发射信号活动增强，而屈服阶段的声发射信号活动减弱,变形过程的声发射信号累积绝对能量值要比未充氢试样低约1个数量级。充氢试样拉伸产生的声发射信号比未充氢试样的信号幅值降低约0.33mV，频宽降低0.06MHz。通过对声发射信号的分析发现，充氢试样变形的微观机制为氢促进位错发射与运动，而交叉滑移受到抑制。

声发射；Cr-Mo钢；充氢；位错运动；拉伸变形

Abstract： Tensile test was conducted on 2.25Cr-1Mo steel specimens that were electrochemically hydrogen charged and acoustic emission signals were collected in the real-time stretching process. The results show that tensile strength of 2.25Cr-1Mo steel with hydrogen charging is 536.30MPa, decreased by approximately 57MPa and reduction of area is 43.62%, decreased by 7%, compared with the specimens without hydrogen charging. Hydrogen embrittlement-induced regions known as “fisheyes” and quasi-cleavage morphology are observed on the tensile fracture surface. The AE signals activity in the elastic stage of hydrogen charged 2.25Cr-1Mo steel is enhanced, but the acoustic emission signals activity in the yield stage is decreased. The cumulative absolute energy of AE signals of hydrogen charged specimens during deformation is almost one order magnitude lower than that without hydrogen charged specimens. The AE signals amplitude generated by the hydrogen charged specimens is about 0.33mV lower than that of the specimens without hydrogen charging during tensile deformation, and that the bandwidth of signal is reduced by 0.06MHz. Though the analysis of AE signals, it is found that tensile deformation microscopic mechanism of hydrogen charged specimens is that dislocation emission and motion is enhanced but dislocation cross-slip is inhibited by hydrogen.

Keywords：acoustic emission；Cr-Mo steel；hydrogen charging；dislocation motion；tensile deformation

2.25Cr-1Mo钢广泛用于制造热壁加氢反应器，其长期在高温(375～575℃)、高压(6.9～28MPa)和临氢环境(H2，H2S)的恶劣条件下服役，不可避免地发生氢脆问题。少量氢渗入和溶解使得2.25Cr-1Mo钢力学性能发生明显劣化[1]，如金属塑性下降、断裂韧度和抗疲劳性能降低、诱发裂纹等[2,3]，为装置的安全运行埋下了隐患。以往人们利用挂块性能测试的方法定期评估器壁材料的脆化情况，此方法不仅工作量大，而且往往不能准确反映器壁材料的真实状态，因此，亟须找到一种有效的无损检测方法，评估器壁材料的脆化程度[4]。……