冷却方式对CB2钢中BN相形态及力学性能的影响

为研究冷却方式对新一代铁素体耐热钢中BN相形态及力学性能的影响,制备了含B质量分数为0.012%的CB2钢,经过1 100℃奥氏体化后,分别进行了空冷和水冷.结果表明:经过奥氏体化的CB2钢随着冷却速度的增加,基体中BN相的尺寸随着减小,水冷试样的基体中出现尺寸为600 nm的BN相,并且试样的力学性能都得到了提升;空冷试样中BN相呈不规则块状,内部出现裂纹和碎裂现象,而水冷试样中BN相呈长方体型,结构紧实;冷却速度的增加,缩短了CB2钢基体中BN晶核长大阶段的时间,而过冷度的增大,使BN的形核率增加,因而在基体中形成弥散分布的细小BN相.

Effect of Cooling Mode on BN Phase Morphology and Mechanical Properties of CB2 Steel

To study the effect of cooling mode on the BN phase morphology and mechanical properties of a new generation ferritic heat resistant steel， the CB2 steel with the B content of 0.012% after 1100℃ austenitizing was carried out by the air-cooling and water-cooling treatment， respectively. The results showed that the size of the BN phase in the austenitized CB2 steel reduced with the increase of cooling rate.A BN phase with 600nm size was observed in the water-cooled CB2 steel sample， associated with the increase of mechanical property.The BN phases were irregular blocks in an air-cooled sample， associated with internal cracks and fracture， while they were compact rectangles in a water-cooled one.Because the growth rate of BN nuclei increased with the increase of cooling rate and the nucleation rate of BN phase increased with the increase of supercooling degree， it was found that the refiner BN phases were dispersed in the CB2.