Study On The Relation Between Spectrum Signal And Welding Quality Of Laser Welding Of Different Aluminium Alloy

Lightweight is an important measure for the realization of reduction, and it iscrucial of using lightweight materials such as aluminum alloy. Compared with theconventional fusion welding, laser welding uses laser beam as heat source, and it hasmany advantages such as high energy density,heat concentrated, easy to control theheat source,weld large depth width ratio, narrow heat affected zone, small weldingdeformation and high efficiency and high automation and so on. Laser welding is theideal method for dissimilar aluminum alloys, but there are uncertain factorsand many variables in the welding process.While checking the offline welding,it istime-consuming and laborious and poor flexibility, so real-time monitoring oflight, sound, electricity characteristic information in the welding process andestablishing the connection between the characteristic information of weldingprocess and the quality performance of the weldment by adjusting and optimizing thewelding parameters, controlling the generation of welding defects become thefocus and difficulty in the study of laser welding of dissimilar aluminum alloy. Thispaper selects the vehicle5083/6016aluminum alloy as the research object whenthe fiber laser is used to the laser welding experiments of plate specimen. Usingspectroscopic measurement system, scanning electron microscope, vickers microhard--ness machine, microcomputer control electronic universal testing machine, thetime-domain MgI generated by the dissimilar alloy laser welding plasma is tested andthe weld appearance, microhardness and mechanical is analyzed. The relation betweenthe process parameters and welding quality performance is studied. Finite elementcommercial software Procast is used to get welding molten pool temperature fieldunder the condition of optimizing the process. Based on relation between the MgIsignal and welding quality performance,the method of adding powder to controlwelding defects is given. The results of the study is expected to provide theoreticaland experimental basis of laser welding of aluminium alloy.During welding the5083/6016dissimilar aluminum alloy，it is found that there isa connection between the average relative spectrum intensity of MgI and technologyparameter：with the increase of scanning speed，the spectrum signal strength of MgIwill be reduced;The defocusingamount has obvious effect on the spectrum signal ofMgI,but the laser power has smaller effect on the chang of the whole range of thespectrum signal.There is also a connection between the average relative spectrum intensity of MgI and the performance of the quality of weldment：with the smaller orlarger MgI spectrum intensity，the test specimen will appeare some phenomenon——lack of penetration or melt through；At the area where the plasma signal of MgI wavedmore heavily will appeare the defect such as undercut,hollow, pore and had a worsemechanical property while the signal is stable, the welding will be flat little defectand the better mechanical propertyUsing the equivalent specific heat capacity treatment latent heat, through acomprehensive analysis of the laser heat source, establish the Gaussian surface heatand point heat source model. Simulation under optimal conditions weldment bathtemperature field based, found that the temperature of the workpiece surface from thecenter of the weld different locations consistent with the laser welding with thecomputer acquisition system basically test; Based on the temperature fielddistribution of the pool and picked MgI signals from the high temperature plasmaspectroscopy. Real-time control of the welding process X-Rs figure is establishedby using of the Hugh hart of SPC control theory,and provided the basis forreal-time monitoring of the welding process. On-line monitoring program is written,and the spectral signal abnormalities is tracked to recognize defeact location in theweldment; In order to ensure stable welding quality, Cu powder is added to weldingtests.It is found that after adding powder, MgI spectrum signal becomes stable andfluctuation is improved.A real-time control of welding process X-Rs figure isestablished to monitor real-time welding process by using Hugh hart SPC controltheory based on the signal strength and quality of weldment MgI spectra of a certainrelation.At the same time, the online monitoring program is programmed to findabnormal signal to carry out at the reverse tracking and determining its location andposition. Prefabricated cu powder experiment is carried out to make up for alloystrengthening element and it is found that after prefabricated Cu powder, MgIspectrum signal is relatively stable and weld formability is improved. Fluctuationsituation is improved and good weld forming is got under different signals.