周兆
,
纪士辰
,
胡壮麒
,
师昌绪
金属学报
采用声发射测试技术,对Al-Si和Al-Cu系合金凝固过程进行监测,证实合金在凝固过程中存在声发射现象,表现为两个声发射信号计数率峰,两个峰的总计数都随着合金中气体含量增加而增高。本文对Al-Si,Al-Cu合金系产生声发射现象的机理进行了探讨,同时,借助其它实验手段证实了声发射信号与合金凝固中气体析出有很好的对应性。第一个计数率峰与气泡在枝晶臂间形核相吻合。第二个计数率峰与凝固末期的枝晶间拉裂现象相对应,可能是氢在枝晶间析出和聚集产生高压氢导致的拉裂。
关键词:
铝合金
,
acoustic emission
,
solidification
,
hydrogen in alloys
ZHU Zuming Institute of Metal Reasearch
,
Academia Sinica
,
Shenyang
,
PRC.
材料科学技术（英文）
The longitudinal(L),long-transverse(T) and short-transverse(S)orientated samples of precipitation-strengthened 7075-T651 aluminum alloy were examined. The acoustic emission(AE)characteristics measured during tensile deformation in the alloy were related to prior aging treatment and orienta- tions of samples. A rms AE peak occurred in all the samples at plastic strain greater than one percent. The heights of peaks have been measured as a function of prior heat treatment.The shift of the peak location was dependent on heat treat- ment in samples with L- and T-orientation. The pre-yield,burst-type emission(PYBE)were observed in S-orientated samples.The behaviours of PYBE were as a function of prior ageing treat- ment too. The stress and plastic strains at which the AE peak stress were generated were consistent with the peaks arising from the fracture and debonding of inclusions.Waveform frequency analysis of AE signals and fractographic observa- tions using SEM as well as data of microhardness and charpy test were also consistent with be- haviours of AE,that is,high stress required for the rms peak or the initiation of the PYBE, was higher for the heat treatment,at which the interface between inclusion and matrix was weaker.
关键词:
acoustic emission
,
null
,
null
,
null
ZHU Ziyong V.A.Marichev Institute of Physical Chemistry of the Academy of Sciences of the USSR
,
Moscow
,
117171
,
USSR.
材料科学技术（英文）
The ambiguous effect of cathodic polarization on SCC of two high strength steels in 0.1 M Na_2HPO_4 and 0.1 M NaNO_3 has been investigated by means of meas- uring electric resistance(R)and recording acoustic emis- sion(AE)signals simultaneously.Results showed that AE sensitivity strongly depends on K value in different solu- tions.Both anodic and cathodic polarization can acceler- ate crack growth rate at high K values,but it appears that there are only subtle differences in their AE characteristics.AE signals only reflect the macroprocesses of crack growth rather than the elementary ones and can not be used for identification of the micro-mechanisms of SCC.
关键词:
acoustic emission
,
null
,
null
,
null
ZHU Zuming WA NG Zhongguang PENG Jun ** Laboratory of Fatigue and Fracture for Materials
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
110015
,
China.To whom correspondence should be addressed.
材料科学技术（英文）
The acoustic emission(AE)characteristics from the fatigue crack propagation in SM50B-Zc steel were strongly affected by the environment me- dium.The AE feature from the fatigue process both in air and in 3.5% NaCl aqueous solution mani- fested a periodicity which indicated the fatigue ex- tension was discontinuous.The fatigue striation and secondary cracking were the main AE sources during the fatigue crack growth in air.In contrast, AE during the fatigue crack propagation in 3.5% NaCl solution was released from the intergranular fracture and quasicleavage cracking.
关键词:
acoustic emission
,
null
,
null
,
null
,
null
蒋咏秋
,
叶林
,
吴键
,
王兴业
,
杨光松
材料研究学报
用声发射技术确定纤维断裂的位置,从而决定纤维断裂段的长度分布。采用含有单纤维丝的聚合物基复合材枓试件,应用细观力学模型,根据纤维断裂段的长度,确定纤维和基体之间的界面剪切强度。这种方法适用于不透明的复合材料基体,有可能用来测定金属基和陶瓷基复合材料的界面剪切强度。
关键词:
复合材料
,
interfacial shear strength
,
acoustic emission
杨震
,
朱永新
,
孟丽莉等
腐蚀学报（英文）
采用AE技术对超高强度钢37SiMnCrNiMoV在3.5%NaCl 溶液中的SCC行为进行研究.证明在裂纹的稳定扩展区内，裂纹是间歇，跳跃式的扩展.发现 腐蚀裂纹尖端的应力强度因子处于0.7KIC和0.23KIC时，平均每次声发射事件 对应的裂纹扩展量相近；应力强度因子处于035 KIC时，平均每次声发射事件对应 的裂纹扩展量较大；声发射事件的发生频率随应力水平的增加，有很大的增加.腐蚀裂纹扩 展的全过程存在两种不同的声发射信号.还证明了37SiMnCrNiMoV的应力腐蚀裂纹扩展过程 中，氢脆起着主要的作用.提出了计算腐蚀裂纹稳定扩展区内声发射事件累积数的公式.
关键词:
超高强度钢
,
acoustic emission
,
stress c orrosion cracking
