Effect of Cr and Mo on strain ageing behaviour of low carbon steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 527; no. 10; pp. 2538 - 2546
• Main Authors: Pereloma, E.V., Bata, V., Scott, R.I., Smith, R.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25.04.2010; Elsevier
• Subjects: Alloy additions; Applied sciences; Cementite enrichment; Elasticity. Plasticity; Exact sciences and technology; Low carbon steel; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical testing; Metals. Metallurgy; Strain ageing; Mechanical testing; Alloy additions; Low carbon steel; Cementite enrichment; Strain ageing; Solubility; Molybdenum addition; Low alloy steel; Tension test; Chromium steels; Transmission electron microscopy; Kinetics; Strain rate
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2009.12.040

This work explores the effects of Cr (0.26–0.74 wt%) and Mo (0.09–0.3 wt%) additions on the kinetics of strain ageing process in low carbon steel. The strain ageing behaviour of the steels was investigated by using tensile tests and transmission electron microscopy. The results have shown that Mo-alloyed steels undergo the same four stages of ageing as unalloyed low carbon steel, whereas Cr-alloyed steels exhibit only three stages of ageing. At the same time, the addition of Mo accelerates the ageing response, while alloying with Cr reduces the rate of strain ageing by ∼3 times in comparison with non-alloyed low carbon steel. It especially delays the offset of Stage III. This is explained by the reduction of carbon content in ferrite due to the enrichment of cementite with Cr leading to the reduction of its equilibrium solubility in ferrite.