Mechanical Properties of Different Austenitic High‐Nitrogen Steel Grades Produced by Powder Mixtures

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The advantages of nitrogen as an alloying element in austenitic stainless steels has been recognized for decades. However, its solubility varies across steel phases, with the highest in the austenitic solid state. Recent studies show that Si3N4 and X2CrNi18‐9 (AISI 304L) powder mixtures enable solid‐state alloy formation. During hot isostatic pressing (HIP), Si3N4 dissolves, allowing nitrogen diffusion into the austenitic matrix, forming high‐nitrogen steel (HNS). This study examines the mechanical properties of HNS produced via powder metallurgy HIP and additive manufacturing using a shell‐core scanning strategy, followed by HIP densification. Processing routes significantly affect microstructure and nitrogen content. Clear trends are found between hardness, tensile strength, and high‐cycle fatigue strength, influenced by processing conditions and nitrogen levels. Additionally, Si3N4 particle size distribution impacts microstructure, with larger particles reducing grain size and enhancing strength. A linear relationship is observed between nitrogen content and both hardness and tensile strength.