Effect Of Heat Treatment On Microstructures And Mechanical Properties Of Point-Mode Forging And Laser Forming GH4169 Alloy

GH4169 alloy was initially used as a nickel-based high-temperature alloy mainly in aerospace applications,with the foreign grade Inconel 718.GH4169 has a very wide range of applications in aerospace,chemical,metallurgical and energy fields because of its ability to withstand large complex stresses and maintain good mechanical properties and surface stability at environments above 600°C.In this paper,by using a combination of point forging(PF)and laser deposition(LF)techniques,the non-equilibrium rapid solidification organization of laser-deposited GH4169 alloy is made to undergo intense plastic cold deformation under the action of point forging,accumulating large plastic deformation energy and providing driving force for subsequent recrystallization.The formed alloy parts are then heat treated,which helps to eliminate some defects in the original state samples and allows for tissue property tuning of the material.In this paper,the effect of heat treatment regime on the organization and properties of point-forged laser-deposited GH4169 alloy is investigated.Optical microscope,scanning electron microscope,universal tensile specimen machine and micro hardness tester were used to observe and measure the organization and properties of the alloy in the pristine state and conventional heat treatment state.It was found that with the increase of the solid solution temperature,the dissolution and recrystallization of various phases in the alloy occurred,and the recrystallized grain size grew gradually,but the mechanical properties of the alloy after the conventional heat treatment were not improved,and the alloy showed brittle fracture at room temperature in tension.In order to further improve the mechanical properties of PF-LF GH4169 alloy,the direction of aging treatment time can be explored.It was found that with the same solid solution temperature,the organization and strength of the alloy did not change much with the shortening of the aging time,but the plasticity of the alloy was improved substantially,far beyond the level of forgings.The basis for the subsequent experiments to explore the effect of simplified heat treatment regime on the properties of GH4169 alloy was laid.The heat treatment system with simplified aging time was used to test the PF-LF GH4169 alloy at different solid solution temperatures,and it was found that recrystallization occurred at a solid solution temperature of 1010°C.The recrystallized grain size was about 6.8 ?m,which reached the previously expected superfine crystal phenomenon.With the increase of solid solution temperature,the recrystallized grain size of the alloy also grew,and the Laves phase disappeared completely at 1050 ?.Meanwhile,under the condition of high temperature double solid solution,a large number of annealed twins appeared in the alloy,which adversely affected the properties of GH4169 alloy.