Fracture of High Carbon Microalloyed Steel Bars Used for Fracture Splitting Con-Rods

Abstract:

A failure investigation has been conducted on high carbon microalloyed steel used in engine fracture splitting con-rods. The fracture occurred when the as-rolled bars are cut down. The study involved the in-depth examination of the chemical composition, microstructures, mechanical properties and fracture morphologies of specimens from failed bars. Results indicated that the chemical composition of the as-rolled material, microstructure, and mechanical properties are within the range of the technical specification. Microstructure is ferrite-pearlite with dominance of pearlite due to the relatively high carbon content. SEM of fracture surfaces of failed as-rolled bars illustrates that the fractography is cleavage steps and river line pattern. It indicates that failure mode is brittle and the mechanism of fracture is cleavage. Microfracturography shows sulphur inclusions and oxides are the fracture initiation. The continuous network proeutectoid ferrite at the edge of fracture bar will prodigiously improve the brittleness and quickly bring stress concentration under dynamic loading conditions. Furthermore, coarseness and narrowband shape ferrite will induce to decrease toughness.

• Periodical: Advanced Materials Research (Volumes 535-537)
• Pages: 561-565
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.535-537.561
• Online since: June 2012
• Authors: Xian Zhong Zhang, Qing Feng Chen, Yu Zhang Xiong, Zhu Tao Xu
• Keywords: Brittleness, Fractography, Fracture, High Carbon Microalloyed Steel

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