SGER: Paraequilibrium Carburization of Ferritic and Martensitic Stainless Steels

SGER：铁素体和马氏体不锈钢的准平衡渗碳

• 批准号: 0633867
• 负责人: Arthur Heuer
• 金额: $ 8万
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0633867&HistoricalAwards=false
• 关键词: SGER; Paraequilibrium; Carburization; Ferritic; Martensitic

TECHNICAL: Research directed towards low temperature paraequilibrium carburization of ferritic stainless steels will be done. Paraequilibrium here refers to conditions where carbon interstitials are mobile, whereas substitutional solutes such as Cr and Ni are effectively frozen because of the low temperatures of the carburization heat treatment. Prior studies have demonstrated that carburization of austenitic stainless steels, e.g. 316L, allows surface carbon concentrations of ~ 14 at % to be realized but absent carbide formation, and with a case ~ 25 um thick, having a Vickers hardness of 1200. Such hardened austenitic stainless steels have improved wear resistance and enhanced corrosion resistance, without significant attenuation of the inherent ductility of austenitic steels. Further, fatigue life of these austenitic steels containing such hardened cases are significantly increased, because of the residual compressive stresses generated during carburization. The high risk, high profit payoff research is intended to explore the potential for paraequilibrium carburization of ferritic stainless steels. Preliminary experiments involving a PH 13-8 Mo stainless steel which has a bcc matrix indicate that Vickers hardnesses up to 1400 may be possible. Knowledge of paraequilibrium carburization of ferritic materials is virtually nil. PIs will undertake experiments with EBRITE (Registered), a commercial alloy with a particularly simple chemistry, to establish conditions under which low temperatures carburization absent carbide formation may be possible for ferritic stainless steels. In addition the response of two martensitic stainless steels, M152 and Ph-17-4, will be examined in this exploratory project. NON-TECHNICAL: The broader impact of the research concerns extending the utility of ferritic stainless steels in many applications. In particular, being able to improve their wear resistance, fatigue resistance and corrosion resistance, without attenuation of other properties, by a low cost conformal process that can be applied to finished components, as carburization involves virtually no dimensional changes, can be considered a disruptive technology. With the improved properties resulting from paraequilibrium carburization, the costs: benefit ratio changes in such a way that ferritic stainless steel will be preferred materials in many applications that now require more expensive materials, or will extend the lifetime of components currently fabricated from stainless steels. On the pedagogical front, the combination of materials science subdisciplines that have to be brought to bear on this research - thermodynamics, kinetics, microstructural characterization, and mechanical behavior - makes this topic an ideal topic for graduate education in materials science.

技术：研究方向是铁素体不锈钢的低温准平衡渗碳。这里的准平衡指的是碳溶质是移动的，而置换溶质如Cr和Ni由于渗碳热处理的低温而被有效地冻结的条件。先前的研究已经证明，奥氏体不锈钢（例如316L）的渗碳允许实现约14原子%的表面碳浓度，但没有碳化物形成，并且具有约25 μ π ι厚的表面，具有1200的维氏硬度。这种硬化的奥氏体不锈钢具有改善的耐磨性和增强的耐腐蚀性，而不会显著减弱奥氏体钢的固有延展性。此外，由于在渗碳过程中产生的残余压应力，含有这种硬化层的这些奥氏体钢的疲劳寿命显著增加。高风险、高收益的研究旨在探索铁素体不锈钢准平衡渗碳的潜力。初步实验涉及PH 13-8 Mo不锈钢，其具有bcc基体，表明维氏硬度高达1400是可能的。铁素体材料的准平衡渗碳知识几乎为零。PI将对EBRITE（注册）进行实验，EBRITE是一种化学成分特别简单的商业合金，以确定铁素体不锈钢可能在低温下渗碳而不形成碳化物的条件。此外，在本探索性项目中还将检查两种马氏体不锈钢M152和Ph-17-4的响应。非技术性：该研究的更广泛影响涉及扩展铁素体不锈钢在许多应用中的实用性。特别地，能够通过可以应用于成品部件的低成本保形工艺来改善它们的耐磨性、抗疲劳性和抗腐蚀性，而不削弱其他性能，因为渗碳几乎不涉及尺寸变化，可以被认为是一种突破性技术。由于准平衡渗碳带来的性能改善，成本：效益比以这样的方式变化，即铁素体不锈钢将是现在需要更昂贵材料的许多应用中的优选材料，或者将延长目前由不锈钢制造的部件的寿命。在教学方面，材料科学的子学科，必须承担这项研究的组合-热力学，动力学，微观结构表征和机械行为-使这一主题成为材料科学研究生教育的理想课题。