Microstructure and tensile properties of AISI 321 stainless steel with aluminizing and annealing treatment. (July 2021)

• Record Type: Journal Article
• Authors: Li, Wei; Chen, Huitao; Li, Cong; Huang, Weiying; Chen, Jian; Zuo, Lu; Ren, Yanjie; He, Jianjun; Zhang, Shengde
• Is Part Of: Materials & design. Volume 205(2021)
• Publication Date: 2021-07
• Subjects: 321 Austenite stainless steel -- Aluminizing -- Annealing treatment after aluminizing -- Tensile properties -- Microstructure; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2021.109729
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: Aluminizing and annealing treatment was applied to AISI 321 stainless steel; Thick aluminized coatings and small NiAl phase were introduced by annealing; More obvious grain growth and improved twin fraction occurred in annealing sample; Higher ductility and lower strength are developed though annealing treatment; Micropore aggregation fracture is the main failure model for both treated samples. Abstract: In the present work, the tensile properties and microstructure of pack cementation preparing aluminized AISI 321 stainless steel with subsequent annealing treatment was investigated. The results reveal that the coatings of aluminized AISI 321 stainless steel are mainly composed of outermost Al2 O3 layer, Fe-Al compound intermediate layer and Fe(Al, Cr) solid solution diffusion layer. The cross shape precipitate (NiAl) and strip precipitate (Ni3 Al) are observed in Fe(Al, Cr) layer. After annealing, no new phase in aluminized coating is detected, meanwhile, the thickness of the aluminized coatings is increased and the porosity of Fe-Al layer is increased as well. In addition, the size of NiAl precipitates is decreased. The strength and plasticity of stainless steel are degraded by aluminizing treatment. However, after annealing, the aluminized steel exhibits a lower strength but a higher ductility. The crack initiation region of both aluminized steel with or without annealing treatment comprise coarse columnar grains and cleavage planes with river patterns. The fracture model of aluminized steel is cleavage fracture, while a mixed of intergranular and transgranular fracture is observed in aluminized annealed steel.