退火工艺对中碳钢低温热轧组织及力学性能的影响

Effects of Annealing Process on Microstructure and Mechanical Properties of Medium Carbon Steel after Low Temperature Hot Rolling

利用SEM、EBSD、显微硬度计和拉伸试验等方法研究了退火工艺对中碳钢低温热轧组织及力学性能的影响规律。结果表明：中碳钢经单向10道次轧制后部分区域渗碳体发生断裂甚至破碎,轧后铁素体平均晶粒尺寸为4μm,抗拉强度为895 MPa,伸长率为10.8%。当轧后试样经550℃退火时,铁素体只发生了回复,退火保温30 min后部分渗碳体发生了球化;650℃退火30 min时,铁素体再结晶已经开始,绝大部分渗碳体球化,部分碳原子发生扩散现象;700℃退火保温30 min,铁素体的再结晶基本完成,渗碳体颗粒分布较均匀。随着退火温度的升高和保温时间的延长,中碳钢的抗拉强度逐渐降低,伸长率显著增加。

The effects of annealing process on the microstructure and mechanical properties of medium carbon steel after low temperature hot rolling were investigated by SEM, EBSD, micro-hardness tester and tensile test. The results show that, after one way 10 times rolling, part of cementite are broken, the average ferrite grain size is 4 ttm, the tensile strength is 895 MPa and the elongation is 10.8%. After rolling and then annealing at 550 ℃, the ferrite has only undergone recovery, and part ofcementite is spheroidized after annealing at 550 ℃ for 30 min. The ferrite recrystallization begins, most of the cementite are spheroidized and some carbon atoms diffuse after annealing at 650 ℃ for 30 rain. The ferrite recrystallization is basically completed, the cementite particles are uniformly distributed after annealing at 700 ℃ for 30 min. With the annealing temperature increasing and the holding time prolonging, the tensile strength of medium carbon steel decreases and the elongation increases remarkably.