SGER: Development of Austempered Ductile Cast Iron with Simultaneous High Yield Strength, Fatigue Strength, and Fracture Toughness by a Two-Step Austempering Process

SGER：通过两步等温淬火工艺开发同时具有高屈服强度、疲劳强度和断裂韧性的等温淬火球墨铸铁

• 批准号: 9907772
• 负责人: Susil Putatunda
• 金额: $ 8万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907772&HistoricalAwards=false
• 关键词: SGER; Development; Austempered; Ductile; Cast

The focus of the high risk, high potential research is to investigate a means of improving the mechanical characteristics of a relatively new, widely used material, ductile cast iron, through a new and novel heat-treating process. Higher yield strengths generally reduce the fracture toughness of materials. Austempered ductile cast iron (ADI) has emerged as a promising engineering material, however in manufacturing situations, simultaneous high yield strength, high fatigue strength and high fracture toughness have not been obtained in ADI. In this exploratory research, a novel and innovative concept of two-step austempering is proposed to solve this problem. The project will establish the feasibility of two-step austempering process and will also establish the right combination of processing parameters so that unique microstructure consisting of (a) very large volume fraction of fine ferrite (b) very fine austenite and (c) very high carbon content in austenite and (d) stable austenite can be produced. This unique microstructure should provide simultaneous high yield strength, fatigue strength and fracture toughness in ADI. This will lead to a high reliability, low cost engineering material with greater durability. Furthermore, it will generate a new class of structural material. Once the validity of this concept of two step austempering has been established, it should be possible to apply this approach in other materials such as low and medium carbon and alloy steels, to produce materials with simultaneous high yield strength, fatigue strength and fracture toughness.

高风险、高潜力研究的重点是研究通过一种新的、新颖的热处理工艺来改善一种相对较新的、广泛使用的材料球墨铸铁的机械特性的方法。较高的屈服强度通常会降低材料的断裂韧性。奥贝球铁（ADI）已成为一种很有前途的工程材料，但在生产应用中，ADI不能同时获得高屈服强度、高疲劳强度和高断裂韧性。在这项探索性的研究中，提出了一种新颖的和创新的概念，两步等温淬火，以解决这个问题。 该项目将确定两步等温淬火工艺的可行性，还将确定工艺参数的正确组合，以便能够产生独特的显微组织，包括（a）非常大体积分数的细铁素体（B）非常细的奥氏体和（c）奥氏体中非常高的碳含量和（d）稳定的奥氏体。这种独特的显微组织应在ADI中同时提供高屈服强度、疲劳强度和断裂韧性。这将导致高可靠性、低成本、具有更大耐久性的工程材料。此外，它将产生一类新的结构材料。一旦两步等温淬火概念的有效性得到确立，就有可能将这种方法应用于其他材料，如低、中碳钢和合金钢，以生产同时具有高屈服强度、疲劳强度和断裂韧性的材料。