A new 1.9 GPa maraging stainless steel strengthened by multiple precipitating species. (5th October 2015)

• Record Type: Journal Article
• Authors: Li, Yongcan; Yan, Wei; Cotton, James D.; Ryan, Glamm J.; Shen, Yifu; Wang, Wei; Shan, Yiyin; Yang, Ke
• Is Part Of: Materials & design. Volume 82(2016:Jun.)
• Page Start: 56
• Page End: 63
• Publication Date: 2015-10-05
• Subjects: Maraging stainless steel -- Atom probe tomography -- Precipitates -- Strengthening; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2015.05.042
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: 3-D reconstruction of the atomic positions of Cr (purple points), Mo (red points) and isoconcentration surface for regions containing more than 35 at.% Ni + Ti + Al (blue surfaces) shows the evolution of precipitates during aging process. Highlights: A new ultra-high strength maraging stainless steel with composition of 13Cr–13Co–4.5Ni–3.5Mo–0.5Ti (at.%) has been designed. A tensile strength of 1.9 GPa combined with reasonable ductility (10% of elongation) was achieved after aging treatment. The evolution of precipitates during aging was investigated using atom probe tomography (APT). The precipitation process of precipitates and their effect on mechanical properties were analyzed. Abstract: A new ultra-high strength maraging stainless steel with composition of 13Cr–13Co–4.5Ni–3.5Mo–0.5Ti (at.%) has been developed. It was demonstrated that the ultimate tensile strength of the steel could reach 1.9 GPa with reasonable ductility. This breakthrough was achieved by a combined strengthening of three different species of precipitates. The evolution of precipitates with respect of size, morphology and chemical composition during aging at 500 °C was characterized using atom probe tomography (APT) and transmission electron microscopy (TEM). The precipitates were identified to be η-phase Ni3 (Ti, Al) phase, Mo-rich R′ phase and Cr-rich α′ phase, developing out of the precursor clusters, Ni–Ti–Al-rich cluster, Mo-rich cluster and Cr-rich cluster, separately. The segregation of Mo and Cr atoms at the precipitate/matrix interfaces was detected and is considered to impede the coarsening of η-phase. Based on the characterizations, the precipitation process of these phases and their effect on mechanical properties were analyzed.