In eddy current testing, the law of attenuation of eddy current(EC) is of great concern. In conductive half space under the excitation of uniform magnetic field, the EC density decreases exponentially in the depth dir...In eddy current testing, the law of attenuation of eddy current(EC) is of great concern. In conductive half space under the excitation of uniform magnetic field, the EC density decreases exponentially in the depth direction. However, in conductor with finite thickness tested by coil, the distribution of EC in the depth direction is more complicated. This paper studies the characteristics of EC attenuation in metallic plate of finite thickness. Simulation results show that there is an EC reflection at the bottom of plate, which changes the law of EC attenuation. A new concept, namely the equivalent attenuation coefficient, is proposed to quantify the speed of EC attenuation. The characteristics of EC attenuation are utilized to explain the nonmonotonic relation between coil voltage and plate thickness. Procedure of selecting frequency is discussed. Thereafter, measurement of plate thickness is carried out and accurate result is obtained.展开更多
The Ar-N2 gas tungsten arc(GTA) welding of 10 mm copper thick plates without preheating was investigated.The microstructure of weld metal and joints was observed and mechanical performance of weld metal was tested by ...The Ar-N2 gas tungsten arc(GTA) welding of 10 mm copper thick plates without preheating was investigated.The microstructure of weld metal and joints was observed and mechanical performance of weld metal was tested by using Cu-Ti welding metal with different Ti content.The Ar-N2 GTA weld of copper thick plates can eliminate the nitrogen porosities in the weld metal by adding element Ti in filler metal,which is caused by N2 gas in shield gas.The elimination degree of nitrogen porosities,the distribution of CuTiN intermetallic compound(IMC) and the mechanical performance of joints are associated with the change of the Ti content in the welding materials.And when Ti content is about 5%,nitrogen porosities is eliminated completely and the CuTiN IMC distribute dispersedly,the tensile strength and impact ductility of the joint achieve the best result,which almost reaches the lever of the base metal.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51277154)Xiamen Key Laboratory of Optoelectronic Transducer Technology+1 种基金Fujian Key Laboratory of Universities and Colleges for Transducer TechnologyInnovative Talents Program of Far East NDT New Technology&Application Forum
文摘In eddy current testing, the law of attenuation of eddy current(EC) is of great concern. In conductive half space under the excitation of uniform magnetic field, the EC density decreases exponentially in the depth direction. However, in conductor with finite thickness tested by coil, the distribution of EC in the depth direction is more complicated. This paper studies the characteristics of EC attenuation in metallic plate of finite thickness. Simulation results show that there is an EC reflection at the bottom of plate, which changes the law of EC attenuation. A new concept, namely the equivalent attenuation coefficient, is proposed to quantify the speed of EC attenuation. The characteristics of EC attenuation are utilized to explain the nonmonotonic relation between coil voltage and plate thickness. Procedure of selecting frequency is discussed. Thereafter, measurement of plate thickness is carried out and accurate result is obtained.
基金Funded by Program of Excellent Team in Harbin Institute of Technology
文摘The Ar-N2 gas tungsten arc(GTA) welding of 10 mm copper thick plates without preheating was investigated.The microstructure of weld metal and joints was observed and mechanical performance of weld metal was tested by using Cu-Ti welding metal with different Ti content.The Ar-N2 GTA weld of copper thick plates can eliminate the nitrogen porosities in the weld metal by adding element Ti in filler metal,which is caused by N2 gas in shield gas.The elimination degree of nitrogen porosities,the distribution of CuTiN intermetallic compound(IMC) and the mechanical performance of joints are associated with the change of the Ti content in the welding materials.And when Ti content is about 5%,nitrogen porosities is eliminated completely and the CuTiN IMC distribute dispersedly,the tensile strength and impact ductility of the joint achieve the best result,which almost reaches the lever of the base metal.
