Research On Forming Process And Temperature Field Of CuAl8 Addictive Manufacturing Based On CMT

As one of the key components in a mixed-flow turbine,guide vanes are prone to defects in previous forming methods,such as sand casting copper alloy guide vanes.However,CMT(Cold Metal Transfer)additive manufacturing method provides a new idea for the rapid forming of parts due to its low cost and short production cycle.Based on the new forming method of copper alloy guide vanes and by means of experiment and numerical simulation,this paper studies the forming process and temperature field of CMT additive manufacturing of CuAl8 aluminum bronze,hoping to improve the forming quality of parts.Firstly,the forming process of single pass and single layer was studied,and the experiment was designed by the method of quadratic regression model.The two fitting equations obtained have high significance,which can predict the weld bead size under different process parameter combinations,and The forming rule under the mutual influence of single factor and double factor is analyzed.The influence of welding current and substrate preheating temperature on the width of cladding layer is positively correlated,and the influence of cladding speed on the width of cladding layer is negatively correlated.Among them,welding current It has the greatest influence on the width of the cladding layer.The effect of the cladding speed on the height of the cladding layer is greater than that of the preheating temperature and welding current.Secondly,the forming technology and structure analysis of the wall block were studied.After determining the welding current and cladding speed,adjusting the arc length compensation coefficient of the CMT welding machine may greatly improve the forming quality.The two samples obtained by the round-trip forming method The ends are flat,and the effects of welding current,cladding speed,and interlayer residence time on the wall forming size and internal appearance structure are compared.The welding current increases,the forming sample is more "flat and wide",and the forming test is performed at a large cladding speed.The appearance of the sample is more flat and narrow,the residence time between the layers is shorter,and the verticality of the wall is the best.With the increase of the residence time between the layers,the height of the straight wall wall gradually increases.Based on the above rules,a CuAl8 block with good forming quality is obtained body.In the forming microstructure,coarser grains appear at the bottom,up to 800 μm,the grain size is gradually uniform along the lifting direction,the maximum value is about 400 μm,the growth direction is also consistent,and the interlayer weight is found throughout the wall In the melting zone,in the remelting zone near the bottom,the radius of curvature of the arc is the smallest,and the depth of the downward melting is the largest.The crystal grains at each position of the forming wall are coarser under the condition of large welding current,and the influence of the cladding speed on the crystal grain size is opposite to the influence of the welding current.Finally,Abaqus was used to build a finite element model of Cu Al’s CMT additive manufacturing process,including a single-pass single-layer weld bead and a singlepass multilayer straight-wall wall.The method of controlling a single variable was used to study different forming paths and different interlayer residence times.Under the distribution of the temperature field,the results show that the heat dissipation mode under the round-trip direction is better.Using the temperature after cooling at the midpoint of different cladding layers as the object of investigation,it is easier to clearly obtain the influence law caused by the residence time between the layers.The shorter the residence time between the layers,the higher the temperature after the cladding layer is cooled,and the layer is reasonably extended The residence time can play a role in controlling the temperature between the layers.