ABSTRACT This study investigates the mechanical properties of Intercritically Austempered Ductile Iron (IADI) obtained after the heat treatment of ductile irons having different as-cast microstructures and Si concentrations. Tensile strength, impact strength and hardness are measured. The results show that it is possible to obtain acceptable IADI microstructures starting from different as cast microstructures, obtaining similar mechanical properties than those obtained starting from fully ferritic matrices. Tensile strength, yield stress and hardness increase when the silicon content in the melt increases and with the amount of ausferrite present in the microstructure. Particularly, IADI achieved on 3.1% Si DI showing approximately 50% of ferrite and 50% of ausferrite have the best combination of mechanical properties. The IADI samples obtained using different chemical compositions and heat treatment parameters allowed to satisfy every grade specified in ASTM A536 standard for ductile iron showing improved elongation at failure.

中文翻译：

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硅含量对铸态显微组织获得的 IADI 力学性能的影响

摘要 本研究调查了具有不同铸态微观结构和 Si 浓度的球墨铸铁热处理后获得的临界等温淬火球墨铸铁 (IADI) 的机械性能。测量拉伸强度、冲击强度和硬度。结果表明，有可能从与铸造微观结构不同的开始获得可接受的 IADI 微观结构，获得与从完全铁素体基体开始获得的那些相似的机械性能。当熔体中的硅含量增加和微观结构中存在的奥铁素体量增加时，拉伸强度、屈服应力和硬度增加。特别是，在 3.1% Si DI 上实现的 IADI 显示大约 50% 的铁素体和 50% 的奥氏体具有最佳的机械性能组合。