Microstructure And Mechanical Properties Of GH4169 Superalloy Fabricated By Electromagnetic Stirring Aided Arc Welding Rapid Forming

GH4169 ni-base super alloy was used as experimental material in this paper, microstructures and mechanical property of GH4169 super alloy fabricated by electromagnetic stirring aided arc welding rapid forming and the process were investigated. The organizing feature of GH4169 super alloy fabricated by electromagnetic stirring aided arc welding rapid forming with different magnetic field strength were revealed by metalloscope and scanning electron microscopy, etc. The effects of main parameters magnetic field strength on hardness, tensile properties and fatigue were studied, obtained the electromagnetic stirring aided effects on the mechanical properties of alloy. The research results are as follows:Process experiment shows, the forming of GH4169 super alloy fabricated by electromagnetic stirring aided arc welding rapid forming has good forming without obvious defects. With the increase of magnetic field strength, the microstructure possesses the dendrites feature with not metallurgical defects, such as porosity reduce, the amount of Laves brittleness phase reduce, the element micro-segregation becomes weaker, but appear the splashing phenomenon; the organization analysis found that the columnar crystal structure which continuous epitaxial grow have the trend which change into the axial grain and grain have some degree refinement after imposed magnetic field; electro-magnetic stirring can decrease the differences of residual stress in the melting area and the interior region. When the magnetic field current is 1A, the microstructure of the equal axial grain structure obviously. But with the further increase of magnetic field strength, the effect of field become weaker.Alloy recrystallization process analysis that compare to not apply electromagnetic stirring aided, the recrystallization start occurs time carry over and requires a longer incubation period with the increase of the magnetic field strength. With the addition of electromagnetic stirring aided, the recrystallization nucleation sites become more random and the difference phenomenon of nucleation sites eliminate. The recrystallization degree becomes more completely in the process of prolonging holding time, recrystallization are fully complete when the holding time is 60 min. With the increase of magnetic field strength, the recrystallization extent increases first and then decreases, finally increases at the same time.With the increase of magnetic field strength, microhardness of the deposited present the change trend that first increases and then decreases, and microhardness reach peak when the magnetic field current is 1A. Microhardness show a downward trend with the solid solution time prolonging,and the microhardness value tends to be uniform when the holding time is 60min; The hardness increases to the peak at the short time and then slowly decreases in the process of prolonging aging time. Compared to the deposited samples, the hardness range of solid solution samples decreased slowly and the range of change is smaller, which only 30 HV. The peak hardness and stability hardness value greater.Similar to the law of hardness change, the strength of the deposited samples also increases firstly and then decreases with the increase of magnetic field strength. Strength reach maximum when the magnetic field current is 1A, the strength increased 78 MPa and the elongation increased 6% compare to the samples which were not apply electromagnetic stirring aided. After heat treatment, the strength and plasticity of the materials are improved, the strength increased 157 Mpa and the elongation increased 9%. The strength of the heat treated samples close to the forging sample.Add electromagnetic stirring can improve fatigue performance of deposited and heat treatment state of GH4169 super alloy fabricated by electromagnetic stirring aided arc welding rapid forming. The fatigue life of deposited and heat treatment state were 1.1 x 105cyc( horizontal stress 365Mpa) and 6.6 x 104cyc( horizontal stress 650Mpa), with the increase of magnetic field strength, the fatigue properties of deposited and heat treatment state are improved at room temperature. The fatigue performance optimal when the magnetic field current is 1A, the fatigue life reached 1.0× 106 cyc and 2.8× 105 cyc. Fatigue performance show a downward change with the further increase of magnetic field strength.