Effect of Deformation on the Microstructure and Hardness of X5CrNi18-10 Wire

Abstract. This study presents the characterization of cold-drawn spring wire made of X5CrNi18-10 (AISI 304) steel. The investigations comprised phase analysis by X-ray diffraction, microstructural observations in longitudinal and transverse sections, and Vickers hardness measurements (HV2). XRD confirmed austenite as the main phase. The measured hardness, HV2 = 549 ± 8, is high compared with values typical of the annealed condition and results from strain hardening induced by cold drawing. The microstructure shows a banded grain structure characteristic of intense plastic deformation, as well as sulfide inclusions (MnS). Revealing the microstructure required oxidizing/tint etchants suitable for chromium–nickel steels in the heavily deformed state. The results are consistent with the requirements of EN 10270-3 and can serve as a reference for testing and quality control of austenitic wires used for spring elements.