论文部分内容阅读
为研究初始晶粒度对SA508-3钢热变形后微观组织的作用规律,将Φ10mm×15mm圆柱形试样置于电阻加热炉中加热并保温不同时间,以获得不同的初始晶粒度。运用面积法测得保温0min、30min和60min后的微观组织晶粒尺寸分别为650μm、950μm和1200μm。设计并进行了楔形试样高温镦粗实验,研究了SA508-3钢不同初始晶粒度在热变形过程中的动态再结晶体积分数和动态再结晶晶粒尺寸的演化规律。结果表明,当楔形试样压下率为50%时,不同初始晶粒尺寸对发生完全动态再结晶的临界应变有较大影响,初始晶粒尺寸越大,发生完全动态再结晶的临界应变越大。当动态再结晶完全发生时,3种不同初始晶粒尺寸对应的热变形后平均晶粒尺寸分别约为70μm、73μm和75μm。表明当变形量超过临界应变促使发生完全动态再结晶时,初始晶粒尺寸基本不影响热变形后的晶粒尺寸。
In order to study the effect of initial grain size on the microstructure of SA508-3 steel after hot deformation, Φ10mm × 15mm cylindrical specimens were heated in a resistance furnace and incubated at different times to obtain different initial grain sizes. Using the area method, the microstructure grain sizes after heat preservation at 0min, 30min and 60min were 650μm, 950μm and 1200μm respectively. The upsetting experiment of wedged specimen was designed and carried out. The dynamic recrystallization volume fraction and the dynamic recrystallization grain size of SA508-3 steel during different hot deformation process were studied. The results show that when the reduction rate of wedge-shaped sample is 50%, the different initial grain size has a great influence on the critical strain of complete dynamic recrystallization. The larger the initial grain size, the more critical strain of complete recrystallization occurs Big. When the dynamic recrystallization completely occurs, the average grain sizes after thermal deformation corresponding to the three different initial grain sizes are about 70 μm, 73 μm and 75 μm, respectively. It shows that the initial grain size does not affect the grain size after thermal deformation basically when the deformation exceeds the critical strain to cause complete dynamic recrystallization.