The Research Of CMT Welding Temperature Field And Molten Pool Fluid Field

The cold metal transfer welding technology is a new technology with low heat input,This paper on the basis of heat transfer and fluid dynamics,Combining with thecharacteristics of CMT welding process and melt dripping transition in one cold one hotalternating,established CMT welding3D transient temperature field and fluid fieldmathematical model of the molten pool.The research will play an important role foraccurately describe the CMT welding dynamic process and occurred in the deepunderstanding of CMT welding dynamic process of the phenomenon and law.This paper uses the established mathematical model,on the basis of NO.2parameters,researched the CMT welding temperature field and fluid field distribution in and dynamicvariation.According to the results, along with the welding process, temperature rising,weldpool growing up, velocity increaseing, the temperature field and fluid field distribution isalso gradually expanding,and the isotherm in front of heat source is dense, the temperaturegradient is bigger, the rear isotherm is relatively sparse, the temperature gradient is smaller,fluid from the heat source center to spread around the pool. When the welding processachieve the quasi steady state, the temperature field and fluid field distribution wasbasically stable. The entire process of welding molten pool of the highest temperature is2047k, the maximum velocity of molten pool fluid is0.069m/s.Based on the build model, changing the welding procedure specification,studied theinfluence of welding specification parameters for CMT welding temperature field andmolten pool fluid field. The calculations show that on the different specification parameters,the distribution shape of CMT welding temperature field and molten pool fluid field areroughly the same. But with the increase of welding speed, temperature field and fluid fielddistribution range reduced, molten pool size, maximum temperature, and fluid flowvelocity decreases, During the welding process, the highest molten pool temperature ofNO.1,NO.2and NO.3is2125k,2047k and2125k,, the maximum velocity of molten poolfluid is0.076m/s,0.069m/s,0.054m/s; With the increase of welding current, temperaturefield and fluid field distribution range increase, molten pool size, maximum temperature,and fluid flow velocity increases, During the welding process, the highest molten pooltemperature of NO.2,NO.4and NO.5is2047K、1926K、2218K,the maximum velocity ofmolten pool fluid is0.069m/s、0.048m/s、0.085m/s. In CMT welding cold-hot alternating phase, a pulse cycle is studied under the actionof peak temperature and base temperature of the welding temperature field and molten poolfluid field changing process. The calculations show that under the action of peaktemperature and base temperature,temperature field in the basic no change, the shape offluid field distribution is roughly the same, But the peak temperature of molten pool in thepulse cycle maximum velocity is0.055m/s, the base temperature of molten pool maximumvelocity is0.006m/s.On the basic of NO.2parameters, calculate the molten pool fluid field under a separatedriving force. The calculations show that during the CMT welding process, buoyancy makefluid flow from the edge to the center, the largest velocity is0.0076m/s, electromagneticforce makes the fluid from the center to spread around, maximum velocity of0.055m/s, thegravity of fluid flow rate had little effect. So the main driving force of CMT weldingmolten pool fluid field is electromagnetic force.Using the simulated process parameters, make the CMT welding experiment plan,compared with the macro-morphology of the weld experiment and the simulation, observethe fusion line shape, found that fits in.