Aluminum-alloyed lightweight stainless steels strengthened by B2-(Ni,Fe)Al precipitates

Materials & Design

R. Rahimi¹  J. Mola²  M. Zupan²  H. Biermann³  M. Duffy⁴  A. Zargaran⁵  G. Chen⁶  M. Harwarth⁶ 

[1] The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, 430081 Wuhan, China;Department of Mechanical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA;Formerly with Institute of Iron and Steel Technology, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany;Graduate Institute of Ferrous Technology (GIFT), Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea;Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany;Materials Design and Structural Integrity Laboratory, Faculty of Engineering and Computer Sciences, Osnabrück University of Applied Sciences, 49076 Osnabrück, Germany;

关键词: Lightweight steel;    Al addition;    Stainless steel;    Martensite;    B2-(Ni,Fe)Al;    Intermetallic precipitates;   

DOI  :  

来源: DOAJ

【 摘 要 】

The age hardenability of Al-alloyed lightweight stainless steels with the base chemical composition Fe–10.5Cr–3Al (wt.%) and Ni concentrations in the range 3–15 wt.% was studied. Alloys containing 3% and 6% Ni exhibited almost fully ferritic matrix microstructures and a weak age hardening response. Alloys containing 9%, 12%, and 15% Ni, on the other hand, developed primarily martensitic microstructures. Differential scanning calorimetry measurements indicated the occurrence of an exothermic reaction in the approximate temperature range 375–625 °C. Dilatometry measurements indicated that the exothermic reaction was accompanied by a net contraction. Hardness measurements after aging for 5 min indicated significant hardening of alloys already at 350 °C due to the formation of B2-(Ni,Fe)Al intermetallic precipitates. The age hardening response was significantly superior to that of conventional precipitation-hardenable martensitic stainless steels. Tensile elongation in the aged condition was negatively influenced by the presence of soft ferrite regions. Processing conditions associated with a fully martensitic microstructure prior to aging are required to render a uniform age hardening response. Guidelines for the development of a new family of lightweight precipitation-hardenable steels with lower raw material costs and a higher corrosion resistance compared to the standard 18Ni maraging steels are provided.

【 授权许可】

Unknown