中文摘要：

本文利用声发射装置采集了Q345钢和H62黄铜两种材料拉伸过程中的动态声信号。结果发现两种材料在线弹性阶段末端都会产生大量声发射信号,但有明显屈服流动的Q345钢在硬化阶段的开始时段也会产生信号峰值。为了研究两种材料在拉伸变形过程中声发射的微观机制,本文采用扫描电镜下原位拉伸实验方式观察了两种材料在不同拉应力下晶粒内部滑移线的产生和演变过程。在此基础上总结出了两种材料声发射信号与力学行为的关系,指出应以第一次声发射信号的峰值对应的工作应力作为材料屈服应力及其合理性,并按此标准给出H62黄铜的屈服应力为193MPa。

英文摘要：

In this paper,acoustic emission（AE）device was used to acquire the dynamic AE signals of Q345 steel and H62 brass alloy respectively during tensile deformation process.It is found that a large number of AE signals are generated at the end of linear elastic stage of both materials.But Q345 steel which has obvious yield flow presents another AE signal peak at the beginning of hardening stage.In order to study AE microscopic mechanism of both materials during tensile deformation,scanning electron microscope（SEM）was used for in-situ tensile experiment,the formation and evolution of crystal grain internal glide line under different tensile stresses was observed.Based on above results,relationship between acoustic emission signals and mechanical behavior of both materials was summarized.It is pointed that the working stress corresponding to the peak value of first AE signal should be taken reasonably as yield stress of th material.According to this standard,the yield stress of H62 brass alloy is 193 MPa.