索氏体化率及夹杂物对82B盘条力学性能的影响

Effect of Sorbitizing Rate and Inclusions on Mechanical Properties of 82B Wire Rod

通过成分分析、金相观察、夹杂物形貌观察、能谱分析及拉伸断口分析,研究了82B盘条的索氏体化程度与夹杂物的类型及尺寸对其力学性能的影响。结果表明：82B盘条试样室温组织主要是索氏体与少量先共析铁素体,且索氏体含量均高于80%。索氏体化率低是影响82B盘条的抗拉强度、断面收缩率主要因素。随着索氏体化率增加,82B盘条的抗拉强度也相应增高,而断面收缩率也逐渐增大。82B盘条中的夹杂物主要是氧化物夹杂,且氧化物夹杂主要是Al2O3、SiO2、CaO和Cr O。夹杂物尺寸主要集中在0~20μm,较大尺寸的夹杂物含量较高时,主要对82B盘条断面收缩率的影响较大,并呈显著降低的趋势;而大尺寸的夹杂物对抗拉强度的影响较小。82B盘条拉伸断口属于韧性断裂,主要是剪切唇区和纤维区。纤维区夹杂物主要为氧化物,如Al2O3、CaO,其晶粒尺寸为31.8μm。

The specimens were handled with component analysis, metallographic observation and statistical analysis. The microstructure and morphology of the inclusions were observed by SEM and EDS. The analysis of tensile fxacture was carried on. These experiments were aimed at researching the degree of sorbitizing rate and the type and size of inclusions in the different batch numbers of 82B wire rod. It turns out that sorbets and a small amount of proeutectoid ferrites are the main microstructrure of 82B wire rod. The contents of sorbites in the 82B wire rod are all higher than 80%. The tensile strength and percentage reduction of area of 82B wire rod are mainly affected by lower rates of sorbitizing. As the sorbitizing rate increasing, the tensile strength of 82B wire rod also increases, and the reduction of area also increases gradually. The inclusions of 82B wire rod are main oxide inclusions, and the majority are A12O3, SiO2, CaO, and CrO. The sizes of inclusions are mainly concentrated in 0-20μm. While the content of inclusions in large size is higher, the percentage reduction of area is greatly influenced, and it presents the tendency of remarkable reduction. However, the inclusions in large size have little effects on the tensile strength. The tensile fracture of 82B wire rod belongs to the ductile fracture. It is mainly composed of shear lip area and fiber area. The main inclusions in fiber area are oxide inclusions, such as Al2O3 and CaO. The size of grain is about 31.8 μm.