The Research Of Cmt Welding Technology On Thin Walled Stainless Steel Pipes

In recent years,the supply and demand of automobiles have increased year by year,and the requirements for automotive exhaust systems have also increased considerably.The manufacturing materials of the exhaust system have been developed from traditional carbon steels to aluminized stainless steels,high strength steels,and so on.Aluminized stainless steel began to be used in the manufacture of automobile exhaust system with excellent corrosion resistance.Because of the application of aluminized stainless steel in the automotive exhaust system,the welding method of the exhaust system needs constant improvement.In especial,cold metal transition welding technology(CMT welding technology)is an important means for the exhaust system manufacturers to improve the welding quality of products.However,the actual application range of the CMT is smaller,and there is no corresponding guidance data for the welding process parameters of aluminized stainless steel pipe fittings.Therefore,it is very important to study the CMT welding method of thin-walled aluminum stainless steel pipe,find out the welding parameters such as voltage and current reasonable.It has very important guiding significance for improving production efficiency and product quality.In this paper,409 Al and 439 stainless steel are taken as the research object.The numerical simulation method is used to screen the welding parameters of CMT in order to find a set of suitable current and voltage ranges.On this basis,combined with welding test,5 welding current and 5 welding voltage are adjusted(25 sets of welding tests).Finally,the above methods integrate appearance screening,magnetic particle testing,penetrant testing and air tightness test,the optimum welding parameter value are determined.The results indicated that a finite element model of CMT welding was established.In view of the characteristics of CMT welding "cold-hot-cold" alternation,the heat source model is dealt with.More accurate results was obtained.A large amount of simulation were compared with experimental data.Good quality weldments were obtained when the welding current is 75 A and the welding voltage is 20 V.In addition,these weldments passed the test of integrate appearance screening,nondestructive examination and air tightness test.Test results are in line with quality standards.Through a series of experiments and theoretical analysis,the optimum welding current parameter of stainless steel thin tube is 75 A,and the optimum parameter of welding voltage is 20 V by CMT.