Increasing static recrystallization(SRX)nucleation rate and decreasing grain growth rate are the main ways to obtain uniform and fine grain microstructure by annealing treatment.However,it is contradictory to raise th...Increasing static recrystallization(SRX)nucleation rate and decreasing grain growth rate are the main ways to obtain uniform and fine grain microstructure by annealing treatment.However,it is contradictory to raise the SRX nucleation rate and reduce grain growth rate during isothermal annealing treatment.This is because the increase of the SRX nucleation rate needs to raise annealing temperature,while the decline of grain growth rate needs to reduce the annealing temperature.To solve the contradiction,a novel method named cooling recrystallization annealing treatment(CRT)is designed and verified.For the CRT,the relatively high annealing temperature in the primary stage can promote SRX nucleation,and the gradually decreased annealing temperature can reduce the growth rate of SRX grains.Besides,an aged treatment is first carried out to precipitate high content of theδphase before the CRT.Enoughδphases not only provide large numbers of sites for SRX nucleation but also limit the grain growth due to the pinning effect,especially in the primary high-temperature stage.The results show that the novel method can refine deformed mixed grain microstructure well when the suitable cooling rate,start and final recrystallization annealing temperatures are employed.The deformed mixed grain can be uniformly refined to an average size of 8.26μm with the route of 900℃×12 h+1020℃→970℃×20 min.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51975593,51775564)the Hunan Provincial Natural Science Foundation of China(Grant No.2020JJ4113)。
文摘Increasing static recrystallization(SRX)nucleation rate and decreasing grain growth rate are the main ways to obtain uniform and fine grain microstructure by annealing treatment.However,it is contradictory to raise the SRX nucleation rate and reduce grain growth rate during isothermal annealing treatment.This is because the increase of the SRX nucleation rate needs to raise annealing temperature,while the decline of grain growth rate needs to reduce the annealing temperature.To solve the contradiction,a novel method named cooling recrystallization annealing treatment(CRT)is designed and verified.For the CRT,the relatively high annealing temperature in the primary stage can promote SRX nucleation,and the gradually decreased annealing temperature can reduce the growth rate of SRX grains.Besides,an aged treatment is first carried out to precipitate high content of theδphase before the CRT.Enoughδphases not only provide large numbers of sites for SRX nucleation but also limit the grain growth due to the pinning effect,especially in the primary high-temperature stage.The results show that the novel method can refine deformed mixed grain microstructure well when the suitable cooling rate,start and final recrystallization annealing temperatures are employed.The deformed mixed grain can be uniformly refined to an average size of 8.26μm with the route of 900℃×12 h+1020℃→970℃×20 min.
