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利用扫描电子显微镜、显微硬度计和电子万能试验机研究了在退火温度650℃时,退火时间对双向温轧中碳钢组织演变和力学性能的影响。结果表明,双向5道次温轧铁素体发生回复和再结晶,渗碳体片层完全破碎并球化,分布在铁素体基体上。轧后铁素体晶粒尺寸约5.3μm,显微硬度为248 HV,抗拉强度768 MPa,总延伸率只有11.2%。650℃退火1 h时铁素体发生再结晶,平均晶粒尺寸为3.34μm,硬度和抗拉强度分别减小到228 HV、696 MPa,总延伸率增加到15.3%。随退火时间延长,中碳钢平均晶粒尺寸增加,硬度和抗拉强度继续减小,总延伸率增加。
The effects of annealing time on the microstructure evolution and mechanical properties of carbon steel during two-way warm-rolling at annealing temperature of 650 ℃ were investigated by scanning electron microscope, microhardness tester and electronic universal testing machine. The results show that the two-way 5-pass hot-rolled ferrite reverts and recrystallizes, and the cementite lamellae are completely crushed and spheroidized and distributed on the ferrite matrix. After rolling ferrite grain size of about 5.3μm, micro-hardness 248 HV, tensile strength 768 MPa, the total elongation of only 11.2%. The ferrite recrystallized at 650 ℃ for 1 h, the average grain size was 3.34 μm, the hardness and tensile strength decreased to 228 HV and 696 MPa, respectively, and the total elongation increased to 15.3%. With the extension of annealing time, the average grain size of medium carbon steel increases, the hardness and tensile strength continue to decrease, and the total elongation increases.