摘要
为了改善球墨铸铁的低温冲击性能,研究了不同镍含量对铸态球墨铸铁组织性能的影响和镍含量为0.6%退火态球墨铸铁的组织和低温冲击性能。结果表明不同镍含量下球墨铸铁铸态显微组织均为铁素体＋石墨球＋少量珠光体组成,随着镍含量在0.0%~0.6%之间的增加,铁素体晶粒逐渐细小,石墨球亦逐渐细小圆整,且数量增多,镍含量为0.8%时,石墨球化率和均匀性下降。随着镍含量的增加,珠光体的含量增加,球墨铸铁的硬度和抗拉强度逐渐提高,屈服强度先升高后下降,而伸长率却总体呈下降趋势。镍含量为0.6%的球墨铸铁经760℃加热,零保温,随即以5℃/min冷却速度降温到620℃后出炉空冷后,得到了铁素体＋石墨球组织,冲击试样在-60℃下仍然属于韧性断裂,冲击功仍高达13.2 J,能够满足工程机械零部件在较低温下工作冲击韧性的需求。
In order to improve the low-temperature impact properties of nodular cast iron, the effects of Ni content of 0.0-0.8% on microstructures and mechanical properties of the as-cast nodular cast iron, and the effects of N i content of 0.6% on microstructure and low temperature impact properties of annealed nodular cast iron were studied. The results show that the microstructure of as-cast nodular cast iron with different Ni contents consists of ferrite, spherical graphite, and a small amount ofpearlite. The ferrite grain is fine gradually, and the spherical graphite is smaller and rounder, and the amount also increases, with the increase of the Ni content in the range of 0.0-0.6%.When the Ni content is 0.8%, the rate and uniformity of graphite spheroidization decrease. The content of pearlite increases, the tensile strength and hardness of nodular cast iron increase gradually, while the elongation decreases totally in trend and yield strength increases firstly and then decreases, with the increase of the Ni content. The microstructure of ferrite and spherical graphite with the Ni content of 0.6% is obtained through heating at 760℃,keeping warm at 0℃, and then cooling at the rate of 5℃/min and 620℃ and finally air cooling. Under the condition of-60 ℃, the microstructure of the impact sample exists brittle fracture and the impact energy is 13.2J,which can meet the requirements of impact toughness at lower temperature for project machinery parts.
出处
《热加工工艺》
CSCD
北大核心
2016年第15期81-84,共4页
Hot Working Technology
关键词
镍
球墨铸铁
退火
组织性能
冲击功
nickel
ductile cast iron
annealing
microstructure performance
impact energy
