Effect of nanoprecipitates and grain size on the mechanical properties of advanced structural steels

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 528; no. 15; pp. 4924 - 4926
• Main Authors: Suarez, M.A., Alvarez-Pérez, M.A., Alvarez-Fregoso, O., Juarez-Islas, J.A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.06.2011; Elsevier
• Subjects: API; Applied sciences; Elasticity. Plasticity; Exact sciences and technology; Grain size; Heat treatment; Hot rolling; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Nanostructure; Precipitates; Precipitation; Production techniques; Structural steel; Structural steels; Thermomechanical treatment; Yield strength; Yield strength; Structural steel; Microstructure; Hot rolling; Precipitates; Grain size; Ultimate strength method; Cooling; Transition metal; Tension test; Nanometer scale; Precipitation; Transmission electron microscopy; Microalloyed steel; Martensitic transformation; Thermomechanical treatment; Strain rate
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.03.016

► The composition of the steel responded positively to the thermomechanical processing. ► Yield strength was increased due to micrometric grain size of 2.2 μm. ► Mechanical properties were improved due to nanometric precipitates of 5 nm. ► Yield strength values of the API steel were improved up to 877.9 MPa. The microstructure and nanometric precipitates present in advanced structured steel have been studied by high resolution transmission electron microscopy equipped with energy dispersion X-ray microanalysis, in order to relate the nanometric precipitates and grain size with the improvement of the yield strength value of the API steel. The microstructure and nanometric precipitates of the advanced steel were obtained by a combination of thermo-mechanical controlled hot rolling and accelerated cooling procedures. The API steel composition consisted of hot rolled Nb–Ti microalloyed with: 0.07C, 1.40Mn, 0.24Si, 0.020Al, 0.009P, 0.001S, 0.05Mo, 0.5Cr, 0.05Nb, 0.25Ni, 0.10Cu, 0.012Ti, 0.05N in wt%. As a result, this hot rolled steel tested at a strain rate of 5 × 10 −3 s −1 showed an improved yield strength from 798 MPa to 878 MPa due to the micrometric grain size of 2.2 μm and to the nanometric precipitates with a size of around 5 nm in the microstructure of the steel studied.