铌对过冷灰铸铁组织及性能的影响

Effect of Nb of The Structure and Mechanical Properties of Undercooling Gray Cast Irons

本文研究铌对过冷灰铸铁组织及性能的影响。研究结果表明,铌使过冷灰铸铁中的过冷石墨进一步细化,当铌含量达到0.099%时,铸铁中出现块状石墨;铌对过冷灰铸铁的基体组织无明显影响。铌可提高过冷灰铸铁的力学性能,但含铌量超过0．05%后继续提高铌含量,铸铁的力学性能降低,铌在基体组织中的固溶是力学性能提高的主要原因,而铌含量过高时不规则富铌相析出导致力学性能降低。

Abstract The effect of Nb of the structure and mechanical properti + es of undercooling gray cast irons is studied in the present research. The results demonstrate that the undercool graphite become finer when a trace amount of Nb is addied. When the vontent of Nb is 0. 099%, small lumpy graphite is emerged. Nb has little effct on matrix structure of gray cast irons. The mechanical properties of undercooling gray cast irons are improved by the additjon of Nb , but when the content of Nb is more than 0.050%, the addition of Nb makes mechanical properties worse. The The solid - solution of Nb in matrix of cast iron is the main reason for the increasing of mechanical properties, and it is weakened by the separation of Nb - rich phase with irregular shape .