Corrosion behaviour of an industrial shot-peened and coated automotive spring steel AISI 9254

Mazher Ahmed Yar, Ying Wang, Xiaorong Zhou, Constantinos Soutis

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A high-strength low-alloy steel, AISI 9254 (54SiCr6), is widely used for suspension spring production in the automotive industry. In this work, industrially manufactured zinc phosphate coated helical springs are subjected to detailed microstructural and surface analysis for better understanding of corrosion evolution. The material’s free corrosion potential and anodic/cathodic behaviour were investigated in NaCl solutions and corrosion propagation mechanisms were studied using potentiostatic polarisation on cross-sectional and external surfaces. The bulk material is fully martensite with uniformly distributed MnS inclusions, while the spring surface has a 2–3 μm mechanically deformed region introduced by shot-peening and a thin zinc phosphate coating. The corrosion open circuit potential of bulk material and shot-peened spring surface was about –0.7VSCE without significant difference, while phosphated surface is more noble (more positive potential). MnS inclusions, stimulating the anodic attack in the steel, influence corrosion propagation and pit morphology to a large extent that can have an impact on the spring performance.
    Original languageEnglish
    Article numberVol. 53, No. 8
    Pages (from-to)564
    Number of pages573
    JournalCorrosion Engineering, Science and Technology
    Early online date26 Aug 2018
    DOIs
    Publication statusPublished - 2018

    Keywords

    • Automotive spring, corrosion, 54SiCr6, HSLA, electrochemical properties, aging

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