| Today Aluminum leading a variety of lightweight materials has been widely used in modern industrial production.It can be applied to the field of vehicle,manufacturing,aviation,shipbuilding very well.Worldwide,Terminal growth in aluminum consumption is above 6%,and transport demand growth will more than 8%.The use of lightweight materials,greatly reduced the fuel consumption,this car body lightweight will involve the connection of dissimilar materials,especially the combination of steel and aluminum.Because of the difference of steel aluminum alloy and the physical and chemical properties,using conventional methods to obtain good weld,welding and laser welding has the advantages of high speed,high production efficiency,high energy density,and gradually replace the explosive welding,riveting or welding,to get the car and is widely used in other industries,In this paper,laser welding is used as a method to study the connection of steel and aluminum dissimilar metals.According to the material properties of DP780 galvanized steel and 6016 Aluminum Alloy,a set of process parameters were optimized in order to set up the laser welding parameters for 1400 W laser power,welding speed 0.02m/s,using the finite element software ANSYS in APDL language,the establishment of steel aluminum laser welding of galvanized steel in the model,the model on the 6016 lap mode in Aluminum Alloy,using heat source model for Gauss heat source,Respectively from the longitudinal section along the weld direction,vertical direction of the weld,the direction of numerical simulation considering the heat transfer on the temperature field and distribution are analyzed by numerical simulation.Under the condition of guarantee other parameters constant,contrast analysis of the1300 W,1400 W and 1500 W at the end of the weld center temperature and the heating,the highest temperature of weld results show that the laser power,the greater the laser weldingmolten pool of penetration and with the increase of power,the greater the temperature gradient changes also increase;With the speeding up of the welding speed,welding temperature decreases,can draw with the speeding up of the welding speed,the highest temperature molten pool to reduce gradually,and the fusion width will decrease gradually molten pool.Temperature field analysis accurately based on the results of simulation of the stress field by ANSYS software in thermal structure coupling function,using indirect coupling method to simulate the simulation of steel and aluminum.The path evaluation method in the general post processor of the application software is used to obtain the distribution law of the horizontal and longitudinal residual stress along with the time variation.In the experiment of laser welding process,the fiber laser,using thermocouple temperature measurement method of thermal cycling curve of steel and aluminum dissimilar materials were measured,and the simulation result of the temperature field,the center of welding temperature field and temperature at 1008.38 degrees Celsius,the highest temperature reached 1217.07 at the end of 20 s after cooling,the temperature reached 123.76 degrees phase.Simulation results are consistent with the measured data,the temperature field numerical simulation to verify the reliability.The measurement of residual stress is made by using the method of small hole,and the distribution of transverse and longitudinal residual stress on the specified path is tested,and the results are compared with the simulation results.It is concluded that the trend of transverse residual stress and longitudinal residual stress distribution is consistent with the experimental results,which provides a theory and experiment for the engineering application of laser welding of steel and aluminum dissimilar metal materials. |
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