Cu对厚壁球铁石墨组织和性能的影响

Influence of Copper on Microstructure and Properties of Heavy Nodular Iron Casting

利用自行研制的可模拟大型铸件冷却环境的小型试验装置,研究了在成分相同的同一包球铁铁液中不同w(Cu)(分别为0、0.5%、1.0%、2.0%)对厚壁球铁中石墨形态、基体组织和力学性能的影响。试验结果表明,添加适量的Cu有助于改善厚壁球铁的球化率,使其从未添加的62%提高到约77%;未加Cu的球铁基体组织以铁素体为主,而w(Cu)为2%时基体组织中存在"牛眼状"铁素体和大量的珠光体;此外,添加Cu使球铁的抗拉强度有明显提高,从425 MPa上升到650 MPa以上,但伸长率则呈降低趋势。综合考虑,w(Cu)为0.5%是较为理想的添加量。

The influence of different Cu contents on the graphite morphology, matrix structure and mechanical properties of the heavy section nodular iron was investigated by using a self-developed mini experimental device, which can be used to simulate the cooling environment of the heavy casting, and by adding respectively 0,0.5% ,1.0% ,2.0% copper into the nodular iron melt from a same ladle. Test result showed that by adding proper amount of copper, the nodular graphite percentage of heavy section nodular iron castings could be increased from 62% to 77%. Before adding copper, the matrix structure consisted mainly of ferrite plus a little amount of pearlite, while the matrix structure of the nodular iron with 2% Cu consisted of ＂bull eyes-shaped＂ ferrite and a large quantity of pearlite, and in addition, the tensile strength of the nodular iron was increased from 425 MPa to 650 MPa,however the elongation was decreased. Based on overall consideration, 0.5% was adopted as the proper copper adding amount.