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利用卧式挤压机对GH625合金进行了管材热挤压试验,研究了挤压温度和挤压比对GH625合金管材挤压过程中的力能参数及挤压后管材不同部位的显微组织的影响。结果表明,随着挤压温度的降低和挤压比的升高,最大挤压力逐渐升高。管坯在固定挤压速度40 mm.s-1,预热温度为1150~1200℃和挤压比为3.46~4.10的条件下,可成功挤压出3种规格的GH625合金管材;挤压后的管材由于在挤压过程中发生了动态再结晶组织明显细化,管坯横向组织为等轴的动态再结晶晶粒和原始晶粒组成,纵向组织则由等轴的动态再结晶晶粒及被拉长的原始晶粒组成,呈条带状组织;挤压后管材的外壁、中心、内壁与管材的头部、中部与尾部在热挤压变形过程中,由于变形不均匀发生了不同程度的再结晶,因而存在不同程度的混晶组织。为消除混晶组织,结合设备能力与GH625合金的变形特征,可通过提高坯料挤压的变形温度和挤压比来控制变形的均匀性,并通过切头,去尾和对管材内壁进行少量机加工的方法,可获得具有完全动态再结晶组织的挤压管材。
The hot extrusion test of GH625 alloy was carried out by using horizontal extruder. The effect of extrusion temperature and extrusion ratio on the energy and energy parameters of GH625 alloy pipe during extrusion and the microstructure of different parts of pipe after extrusion influences. The results show that as the extrusion temperature decreases and the extrusion ratio increases, the maximum extrusion pressure gradually increases. Under the conditions of fixed extrusion speed of 40 mm.s-1, preheating temperature of 1150-1200 ℃ and extrusion ratio of 3.46-4.10, three kinds of GH625 alloy pipes can be successfully extruded; after extrusion Of the pipe due to the dynamic recrystallization occurred during the extrusion process was significantly refined, the horizontal tube tissue is equiaxed dynamic recrystallization grains and the original grain composition, the longitudinal organization by the equiaxed dynamic recrystallization grains and Was elongated the original grain composition, was strip-like organization; extruded pipe outer wall, center, inner wall and pipe head, middle and tail in the hot extrusion process, due to uneven deformation occurred in varying degrees Of recrystallization, so there are different degrees of mixed crystal structure. In order to eliminate the mixed crystal structure and combine the capability of equipment with the deformation characteristics of GH625 alloy, the deformation uniformity can be controlled by increasing the deformation temperature and extrusion ratio of the billet extrusion, and by cutting, tailing, Processing methods, can be obtained with fully dynamic recrystallization of the extruded tube.