Welding Process Signal Research Based On Acoustic Emission Technique

In this paper, the characteristics of acoustic emission signal in Q235,45steel, T10and austenitic stainless steel are studied, and also the signal of welding process. The research content include, propagation property of fault signal in different materials, acquired the acoustic emission signal in the process of welding effectively, and the characteristic of different acoustic emission sources.By breaking lead signal simulation material fracture signal, the properties of the signal are studied. According to the time the acoustic emission signal arrived to the sensor, the propagation speed is acquired for different materials; when broken lead signal energy spread a certain distance, the signal energy became decreased, so the decay curve is done according to the size of the attenuation, the result shows that austenitic stainless steel energy attenuation is much serious than the carbon steel.On the basis of the welding signal acquisition system, the TIG welding is marched on different metal materials, the result shows that the number of the signal became more with the increase of current. The signal which has been acquired include the welding arc signal, the arc noise, the phase transition signal and solidification cracking signals during cooling. And the statistic analysis is done on the signal’s amplitude and energy.The parameter analysis method is used. The through figure and distribution figure are carried. The regular of different materials’ welding acoustic emission change along with the current and their distribution regular is discovered. For different material of weld area of metallographic test, weld organization is got.Then the microstructure of weld area is analyzed to find the acoustic emission source. Combined with the above content, the different acoustic emission source in each material is obtained.Based on the Matlab platform, the different acoustic emission source is analyzed, such as solidification process, phase change process and cracking process. The property of spectrum signature and wavelet are much different for different acoustic emission source, and it’s useful to judge the different acoustic emission.