The Study On Microstructure And Performance Of Weld Bead By Vibratory Conditioning

In this paper,HQ100 whose thickness is 10mm was welded using MAG under fixedamplitude and frequency vibration field. The parameters of amplitude and frequency werevaried during welding. Before the vibration welding experiment, the optimal weldingparameters-thermal inpute will be determined through qualification of weldingprocedure.It can exclude the welding process parameters on the impact of vibrationwelding experiments. Through access to relevant literature,eight groups experiments weredesigined with four kind of amplitude and four kind of frequency . After welding, tensiletest, microhardeness, impact test,optical microscopy and scanning electronmicroscopy(SEM) were used to examine the mechanical properties, microstructure andfracture of HQ100 welded joint. The compositions of phase were researched byXRD .More endeavors have been put on investigating the effect of welding processparameters parameters on microstructure and performance of welded joint. Moreendeavors have been put on investigating the effect of different viberation parameters onmicrostructure and performance of welded joint.The acting mechanism of viberation onthe solidifrocess of liication pquid metal in molten pool was revealed.First,the paper studies the influence of welding heat input on the mechanicalproperties and weld microstructurel of welded joint.The experiment can prove that thetensile strength and impact absorbing energy of weld joint and initially increases and thendecreases with the increase of the heat input.The optimal tensile strength and toughnessof welded joint is obtained when the heat input is 11.9KJ/cm.It is analysed that the contentof acicular ferrite of weld is maximum result in the consequence.Secondly,the paper studies the influence of vibration amplitude and vibrationfrequency on the mechanical properties and weld microstructure of welded joint.Theexperiment can prove that welding process is the same, mechanical properties of weldedjoints and microstructure is different under different vibration parameter.When heat inputand vibration frequency is stationary the optimal value of mechanical property is obtained when the vibration amplitude is 0.04mm.When heat input and vibration amplitude isstationary the optimal value of mechanical property is obtained when the vibrationfrequency is 20Hz.On the contrary,the performance of weld will deteriorate.When vibration with stable frequency and vibration amplitude was applied during thewelding process.The vibration have impact on solidification of the molten through threeaction,which include composite force bend , vibration stir and energy input . Three actionslevel is different during different vibration parameters.So the final weld solidificationmicrostructure was different. Composite force bend and vibration stir play a decisive roleaffecting molten pool.