Microstructure Evolution And Mechanical Properties Of Cold Drawn GH4169 Alloy

Precipitation-reinforced nickel-based superalloy GH4169 has excellent comprehensive mechanical properties and good corrosion resistance at high temperatures.It is widely used in the field of aviation including rotor blades,gas turbine wheels and bolts,and extrusion die molding.Due to the high strength of the nickel-based superalloy GH4169,and the parts used in the aviation industry have a higher tolerance level,the processing of alloy plastic molded parts becomes extremely difficult.Since the proper amount of ? phase precipitation can effectively improve the low cycle fatigue performance and creep performance of the alloy,and at the same time reduce the notch sensitivity of the material,this paper uses OM,SEM,TEM and other analytical methods combined with room temperature tensile deformation system to study The strengthening mechanism of the morphology ? phase and ?"/?? can be concluded as follows.1.During the cold drawing process,the microstructure of the solid-solution alloy shows that the grains are gradually elongated along the stretching direction,the grain boundary rotates significantly,the deformation zone increases,the grain boundary area increases,and the grain refinement is obvious.After aging treatment of alloys with different deformation amounts,the precipitation amount of ? phase of the alloy increases obviously with the increase of the deformation amount,and the morphological distribution of ? phase becomes finer and evenly distributed from the original needle shape and the uneven distribution within the grain boundaries.The main factor affecting the deformation resistance of the alloy is the amount of deformation of the alloy.The participation of the twin deformation behavior in the cold drawing process leads to a slower increase in the deformation resistance of the alloy.2.When the solid solution alloy is directly aged at 900 ? and 950 ?,the precipitation of a large number of needle-like ? phases hinders the movement of dislocations,resulting in an increase in the yield strength of the alloy,an increase in hardness,and a decrease in elongation.When aging at 850 ?,the coexistence of ?'' phase and ? phase makes the alloy the worst formability at this time.With the extension of the holding time,the transformation of ?''? ? makes the alloy's yield strength decrease,the hardness decreases,and the extension The rate rises.When aging and holding at 1000 ?,a very small amount of ? phase is precipitated,and the alloy's formability reaches its maximum value.During the heat preservation of alloy ? phase,the needle-shaped ? phase will gradually transform into a spherical shape.The higher the temperature of the ? phase,the faster the spheroidization rate.The ?-phase volume fraction in the ?-phase volume at 980 ? and 1010 ? has a solution-resolving equilibrium stage.In the process of cold deformation,dislocations are more likely to cut through small-sized or spherical delta phases.When dislocations encounter larger-sized delta phases,the dislocations are prone to dislocation jamming at the front of the delta phase.Under the same ? phase content,spherical ? phase(small size ? phase)shows good compatibility with dislocations compared to needle-like(large size)? phase.3.The average size of the disc-shaped ?"phase precipitated by heat treatment is 20-30 nm,and the average size of the spherical ? 'phase is 20 nm.Compared with the strengthening effect of the ? phase,the strengthening of the ?" and ?' phases is more significant.When cold drawing occurs,a small amount of dislocations will pass through the ?"/?'phase in a cut-through or bypass manner,and most of the dislocations will gather at the front of the ?" and ?' phase dense areas to form a dislocation plug product.During the interaction between dislocations and ?"/??,the dislocation plug product,bending of dislocation lines,and stacking faults increase the energy required for cold deformation of the alloy,and the movement resistance of the dislocation becomes bigger.4.The fracture modes of the alloys are all microporous polymerized tough fractures.The ? phase,?"and ?' phase are the core of the microporous nucleus.The fracture morphology is mainly composed of two parts:the fiber region and the shear lip region.In contrast,the fiber area occupies a larger area.In addition,a large number of tough sockets are filled with microscopic fracture tissue photos of the alloy,and the small tough sockets interpenetrate to form a larger tough socket,and at the same time on or around the big tough socket will adhere to the oval the existence of a tough nest.