Microstructure and Mechanical Properties of Laser Direct Energy Deposited Martensitic Stainless Steel 410

• Published in: Micromachines (Basel) Vol. 15; no. 7; p. 837
• Main Authors: Kang, Hyun-Ki, Lee, Hyungsoo, Oh, Chang-Seok, Yoon, Jongcheon
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.06.2024
• Subjects: Additive manufacturing; Carbon; chrome carbide; Chromium carbide; Cooling; Diamond pyramid hardness; Diffraction; directed energy deposition; Ductility; Grain boundaries; Heat treating; Heat treatment; Investigations; Lasers; martensitic stainless steel 410; Martensitic stainless steels; Mechanical properties; Microstructure; Phase transitions; Stainless steel; Temperature; Tempered martensite; Tempering; Tensile strength; additive manufacturing; tempering; chrome carbide; directed energy deposition; martensitic stainless steel 410
• ISSN: 2072-666X; 2072-666X
• DOI: 10.3390/mi15070837

The aim of this work is to study the phase transformations, microstructures, and mechanical properties of martensitic stainless steel (MSS) 410 deposits produced by laser powder-directed energy deposition (LP-DED) additive manufacturing. The LP-DED MSS 410 deposits underwent post-heat treatment, which included austenitizing at 980 °C for 3 h, followed by different tempering treatments at the temperatures of 250, 600, and 750 °C for 5 h, respectively. The analyses of phase transformations and microstructural evolutions of LP-DED MSS 410 were carried out using X-ray diffraction, SEM-EDS, and EBSD. Vickers hardness and tensile strength properties were also measured to analyze the effects of the different tempering heat treatments. It revealed that the as-built MSS 410 has very fine lath martensite, high hardness of about 480 HV , and tensile strength of about 1280 MPa, but elongation was much lower than the post-heat-treated ones. Precipitations of chromium carbide (Cr C ) were most commonly observed at the grain boundaries and the entire matrix at the tempering temperatures of 600 °C and 750 °C. In general, the tensile strength decreased from 1381 MPa to 688 MPa as tempering temperatures increased to 750 °C from 250 °C. Additionally, as the tempering temperature increased, the chromium carbide and tempered martensite structures became coarser.