黑心可锻铸铁的组织及性能研究

Study on Properties and Metallograph of Black Malleable Irons

采用中频炉熔炼得到坯料白口铸铁.采用石墨化退火得到KTH300-06可锻铸铁.通过金相组织分析,铸态白口组织为珠光体加莱氏体;经过石墨化退火得到黑心可锻铸铁组织为铁素体加团絮状石墨.单独用0.007%Bi孕育可锻铸铁铸态组织中渗碳体较不加元素的细小;用0.007%Bi和0.002%的B复合孕育可锻铸铁得到铸态细小均匀网状渗碳体,石墨化后为细小均匀的絮状石墨.经硼铋联合处理的可锻铸铁,抗拉强度提高到348.7 MPa,伸长率6.275%.

The white iron was smelted in a medium frequency induction furnace. Malleable irons were made through graphite annealing treatment. The metallograph of as - cast and heat treatment of malleable irons was analyzed. The metallograph of as - cast white irons was pearlite ＋ Ledeburite. The metallograph of graphite annealing treatment malleable irons was homogenous ferrite ＋ floc graphite. The grains of Fe3 C were fine by adding 0. 007 % Bi. Fine network cementite can be obtained by adding 0.007 % Bi and 0.002% B, and uniform and fine graphite graphite can be obtained after annealing treatment. The tensile strength and elongation of the malleable irons after adding Bi and B were 348.7 MPa and 6. 275% respectively.