Delamination of Pearlitic Steel Wires: The Defining Role of Prior-Drawing Microstructure

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 49; no. 6; pp. 2037 - 2047
• Main Authors: Durgaprasad, A., Giri, S., Lenka, S., Sarkar, Sudip Kumar, Biswas, Aniruddha, Kundu, S., Mishra, S., Chandra, S., Doherty, R. D., Samajdar, I.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-06-2018; Springer Nature B.V
• Subjects: Cemented carbides; Cementite; Characterization and Evaluation of Materials; Chemistry and Materials Science; Delamination; Ferrites; Materials Science; Metallic Materials; Metallurgy; Microstructure; Nanotechnology; Pearlite; Structural Materials; Surfaces and Interfaces; Thin Films; Wire drawing
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-018-4564-9

This article reports the occasional (< 10 pct of the actual production) delamination of pearlitic wires subjected to a drawing strain of ~ 2.5. The original wire rods which exhibited post-drawing delamination had noticeably lower axial alignment of the pearlite: 22 ± 5 pct
vs
34 ± 4 pct in the nondelaminated wires. Although all wires had similar through-thickness texture and stress gradients, delaminated wires had stronger gradients in composition and higher hardness across the ferrite–cementite interface. Carbide dissolution and formation of supersaturated ferrite were clearly correlated with delamination, which could be effectively mitigated by controlled laboratory annealing at 673 K. Direct observations on samples subjected to simple shear revealed significant differences in shear localizations. These were controlled by pearlite morphology and interlamellar spacing. Prior-drawing microstructure of coarse misaligned pearlite thus emerged as a critical factor in the wire drawing-induced delamination of the pearlitic wires.