Microstructural evolution of a FeCo15Cr14Ni4Mo3 maraging steel with high ductility prepared by selective laser melting. (June 2022)

• Record Type: Journal Article
• Authors: Cheng, Zhonghui; Sun, Shengzhi; Du, Xi; Tang, Qing; Shi, Jinguang; Liu, Xiaofeng; Jianrong, Qiu
• Is Part Of: Materials today communications. Volume 31(2022)
• Publication Date: 2022-06
• Subjects: Additive manufacturing -- Selective laser melting -- Maraging steel -- Microstructure -- Mechanical properties; Materials science -- Periodicals; 620.11
• DOI: 10.1016/j.mtcomm.2022.103243
• Languages: English
• ISSNs: 2352-4928

Abstract

Abstract: In this study, FeCo15Cr14Ni4Mo3, a new precipitation hardening martensitic stainless steel with ultra-high ductility, was used for selective laser melting (SLM). SLM technology is gradually applied in mold design and manufacturing, but there are still problems including materials. Maraging stainless steel with high ductility for additive manufacturing can greatly increase the life of mold and solve problems such as mold fracture. However, there are few maraging steels whose ductility after heat treatment exceeds 15%. From the examination of the microstructure characteristics, this study observed a large amount of martensite in the as-built samples and up to 50% of austenite (FCC) remained after aging. In addition, the heat-treated SLM FeCo15Cr14Ni4Mo3 sample shows a finer grain structure compared with the as-built samples. These microstructural features are favorable for enhancing the mechanical properties and ductility. Under optimized aging conditions, the SLM fabricated steel exhibits a tensile strength of 1484 ± 6 MPa, a yield strength of 1376 ± 4 MPa and a large elongation at break of 25 ± 0.6%. These results are promising for the application of the SLM fabricated FeCo15Cr14Ni4Mo3 parts in different fields such as molds. Highlights: A new type of maraging stainless steel suitable for additive manufacturing is provided. The FeCo15Cr14Ni4Mo3 stainless steel parts prepared by SLM process have high density, and the relative density is more than 99.5%. The as-built SLM FeCo15Cr14Ni4Mo3 is composed of austenite and 99.8% martensite phase, and has a tensile strength of 1156 ± 8 MPa and an elongation of 24 ± 0.2%. The SLM FeCo15Cr14Ni4Mo3 sample heat-treated at 550 °C /5 h has more than 50% austenite phase and finer grains than the as-built state, and the tensile strength of this sample is 1484 ± 4 MPa, the yield strength is 1376 ± 6 MPa, and the elongation is 25 ± 0.6%.