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Relationship between Mechanical and Magnetic Properties of the Austempered Ductile Irons

等温淬火球墨铸铁机械性能与磁性能的关系

基本信息

批准号：
62550528
负责人：
KIMURA Yasuo
金额：
$ 1.22万
依托单位：
Tokai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

The good combination of strength and ductility of ductile iron is achieved by austempering. Recently, quality assurance technique of austempered ductile iron has been based on the magnetic characteristics. Relationship between mechanical, magnetic properties and microstructure were determined in austempered ductile iron and 0.6%c steel containing chemical composition of matrix of ductile iron.The tensile strength of austempered duceile iron was 60-80% of austempered steel having chemical composition of matrix. However, impact value and elongation of austempered ductile iron were much lowerthan values of steel. The infulence of spheroidal graphite on elongation and impact value is very pronounced. High impact values were obtained in the conditions of austempering at 330-390゜C for 0.5-10 hours. In these austempering conditions, saturation magnetization was lower, so that large quantities of non-magnetic austenite were retained. For the purpose of improving of impact value and elongation of austempered ductile irons and steel, austenite needed to retain from 20 to 45% in volume fraction. Silicon content and austenitizing temperature influence impact value and elongation of austempered ductile irons and steel. In the austempered ductile iron and steel, tensile strength is in direct proportion to coercivity. Similarly, relationship between hardness and coercivity is linear. The measurements of saturation magnetization could be used for determining volume fraction of retained austenite of ductile iron and steel. The tensile strength and hardness could be estimated closely enough by measuring coercivity of austempered ductile irons and steel.

球墨铸铁的强度和延展性的良好结合是通过等温淬火实现的。最近，等温淬火球墨铸铁的质量保证技术已基于磁特性。研究了等温淬火球墨铸铁和含有基体化学成分的0.6%c钢的力学、磁性能和显微组织之间的关系。等温淬火球墨铸铁的抗拉强度是含有基体化学成分的等温淬火钢的60-80%。然而，等温淬火球墨铸铁的冲击值和延伸率远低于钢的值。球状石墨对伸长率和冲击值的影响非常明显。在330-390゜C等温淬火0.5-10小时的条件下获得了高冲击值。在这些等温回火条件下，饱和磁化强度较低，因此保留了大量的非磁性奥氏体。为了提高等温淬火球墨铸铁和钢的冲击值和延伸率，需要保留奥氏体体积分数20%~45%。硅含量和奥氏体化温度影响等温淬火球墨铸铁和钢的冲击值和延伸率。在等温淬火球墨铸铁和钢中，抗拉强度与矫顽力成正比。同样，硬度和矫顽力之间也呈线性关系。饱和磁化强度的测量可用于测定球墨铸铁和钢中残余奥氏体的体积分数。通过测量等温淬火球墨铸铁和钢的矫顽力，可以足够准确地估计抗拉强度和硬度。