受热不均匀对低碳钢SAE1010板材组织及成形性能的影响

为了研究退火过程受热不均匀对板材组织及成形性能的影响规律,对热轧态SAE1010低碳钢板进行冷轧及连续退火,分析热轧态、冷硬态及退火态钢板边部和芯部的显微组织,分别对退火态钢板边部和芯部试样进行拉伸和折弯试验。结果表明,热轧态试样少量岛状珠光体分布在铁素体晶界处,边部组织晶粒尺寸小于芯部,珠光体中部分片层渗碳体退化为球状。冷硬态板材组织沿轧制方向呈现明显的晶粒破碎特征,退火态边部组织存在较多的大晶粒和粒状渗碳体团,芯部组织较为均匀细小。退火态板材芯部材料伸长率高于边部而强度低于边部,经180°折弯后芯部钢板无开裂而边部出现裂纹。退火温度均匀性对于SAE1010低碳钢板组织和性能具有重要的影响。

Effect of uneven heating on microstructure and forming property of SAE1010 low carbon steel plate

In order to investigate the effect of uneven heating during annealing on the sheet microstructure and forming property, cold rolling and continuous annealing were applied on the hot-rolled SAE1010 low carbon steel plate. The microstructure of the edge and center of hot-rolled, cold-rolled and annealed steel plate was investigated. The tensile and bending tests were carried out on the edge and central samples of the annealed plate. The results showed that a small amount of island-shaped pearlite in the hot-rolled specimens was distributed at the ferrite grain boundary and the grain size of the edge area was smaller than that of the central area. And partial lamellar cementite in the pearlite was degraded to be spherical. The microstructure of the cold-rolled sheet was characterized by the grain breakage along the rolling direction. There were many larger grains and granular cementite clusters in the edge area of the annealed steel, and the microstructure of the central area was relatively tiny and uniform. The elongation of the core material of the annealed sheet was higher than that of the edge, while the strength was smaller than that of the edge. After 180° bending, the core steel plate did not crack and the edges appeared cracks. The annealing temperature uniformity had an important influence on the microstructure and property of SAE1010 low carbon steel sheet.