采用SEM、TEM、XRD及拉伸实验等方法研究了原始组织为层片状珠光体的过共析钢重度冷轧及退火后的微观组织及性能指标。结果表明：在重度冷轧及退火工艺下制备出了晶粒尺度均在亚微米量级的超微细复相组织（铁素体＋渗碳体）,其中等轴铁素体晶粒直径为0.5～0.8μm,晶界上钉扎着平均粒径为0.2～0.4μm球化完全的渗碳体颗粒,而晶界内则出现少量粒径为30～50 nm的渗碳体颗粒;在同一实验条件下,增大变形量、增加退火温度以及保温时间的延长,都能导致渗碳体球化程度的增加;与此同时,复相组织的强度指标显著下降,但其塑性指标明显上升;拉伸断口形貌特征也由脆性断裂（冷轧变形）转变为韧性断裂（退火态）。
Microstructure and properties of a hypereutectoid steel with lamellar pearlite were investigated by means of SEM,TEM,XRD and tensile tests after severe cold-rolling and annealing.The results show that the ultrafine microduplex structure（ferrite＋cementite） with the grain size to sub-micrometer level is produced by severe cold-rolling and annealing.Equiaxed ferrite grain of 0.5-0.8 μm is obtai-ned in the steel.The cementite lamella is spheroidized fully and the diameter of the cementite particle at grain boundary is 0.2-0.4 μm,while a few of cementite particles with diameter of 30-50 nm are observed in grains.Under the same experimental condition,the spheroidization degree of the cementite can be increased though increasing the reduction ratios,annealing temperatures and annealing time.Moreover,the strength of the steel with ultrafine microduplex structure decreases greatly while its ductility increases markedly.Furthermore,the tensile fracture morphology changes from brittle fracture for the cold-rolled steel to ductile fracture for the steel after annealing treatment.
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