Formation and effects of banded structures in 55SiCrA spring steel wire rod

¹ School of Metallurgical and Ecological Engineering University of Science and Technology Beijing, Beijing 100083, P.R. China
e-mail: xiaofei6423@126.com
² Xingtai Iron & Steel Corp., LTD, Xingtai 054027, P.R. China

Received: 3 July 2015
Accepted: 2 October 2015

Abstract

Both the transverse section and the longitudinal section of 55SiCrA spring steel wire rod were etched with nitric acid alcohol solution, and many black and white banded structures (band segregation) could be observed in the intermediate region of the wire rod’s longitudinal section. The white banded structure is a mixed structure of ferrite and pearlite, which is defined as a matrix structure because of the negative segregation in the central zone of the bloom or wire rod. However, the black banded structure is basically a single pearlitic structure, which comes into being after rolling compression of multiple processes on the V-shaped segregation in the bloom. Banded structures in spring steel wire rod are an evident embodiment of an uneven microstructure, and they are bound to affect the fatigue strength of spring steel products, which may cause serious damage to products.