Study On The Wire And Arc Additive Manufacture Technology Of Die Steel

Wire and Arc Additive Manufacture(WAAM),has the advantages of high deposition efficiency,short manufacturing cycle,and less restriction on the size of parts.Particularly suitable for the production of small batches of products and the large-size and complex-shaped components of low-cost,high-efficiency and rapid formation.In this paper,H13 wire was used to study on the process characteristics,forming quality,and performance of additive manufacturing process.The process parameters of single-pass weld formation were optimized.The microstructure and performance of thin-walled parts were analyzed,the cooling device for cylindrical part was designed to realize the continuous formation.Distance between the welds and torch angle with well-formed were found.Single-pass weld performed well with process parameters of welding current I=140A,arc voltage U=25V,welding speed v=4mm/s when ?=1.0mm H13 mold steel wire was used for MIG-AM.A thin-walled part with a height of 160 mm was fabricated with the staggered stacking method.The results of X-ray and penetration test show that the thin-walled part was well-formed,no visible porosity,cracks,or fusion defects.When the cylindrical part was formed,the height of the cylindrical part is uniform with the overlap length is equal to the length of the crater.Thick and large parts need to be welded in multiple passes.When the torch is perpendicular to the surface of the workpiece,the surface is relatively flat when the distance between the passes is 5.5mm,welding current I=140A,arc voltage U=25V and welding speed v=4mm/s.But there was an incomplete fusion defect in the roots of the weld.When the torch angle is 15°,welding current I=140A,arc voltage U=25V and welding speed v=4mm/s,the surface of the molded part is relatively flat and the fusion between the tracks is good,when the distance between the passes change to 4mm.The change of temperature field during the fabricating of thin-walled part was simulated by finite element software.It was found that the number of deposited layers increased,the peak temperature improved.The temperature field remain unchanged after fifth layer.The microstructure and properties of the thin-walled part was analyzed.Anisotropic phenomenon was observed along the transverse and longitudinal directions.The tensile strength/elongation in the X-axis direction is as high as 1187 MPa/11.36%,and the tensile strength/elongation in the Z-axis direction is only 886 MPa/8.2%.There were a large number of dimples in the tensile fractures,which are ductile fractures.The anisotropy disappeared after heat treatment,there were not significant difference between tensile strength values in the X-axis direction and the Z-axis direction after heat treatment.The elongation of thin-walled parts improved and the plasticity increased after annealing at 830° and quenching at 870°.The tensile strength of the thin-walled part increases and the elongation decreases with the elevation of quenching temperature.The fracture changes from a dimple-like transgranular fracture to a mixed fracture mode in which the transgranular and intergranular fracture coexist.XRD examinations showed that the thin-walled parts may contained Fe?Cr?Ni solid solution phase after heat treatment.The XRD patterns of samples obtained by different heat treatment processes have different peak heights.After annealing at 830°,the peak value of the sample at the quenching temperature of 1030°C is the highest,and the crystallization is the best.Micro hardness test results showed that the sample annealing at 870 °C,1030 °C quenching hardness value is the highest,up to 500 HV,830 °C annealing 1030 °C quenched and tempered twice had the lowest hardness value,only 314 HV.