Isothermal Treatment Effects on Precipitates and Tensile Properties of an HSLA Steel
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The relationships between tensile properties and precipitates of a high-strength low-alloy steel depending on the isothermal conditions were investigated. While the isothermally treated steel at 300–500 °C for 1 and 24 h had no significant difference, the steel treated at 500 for 336 h, denoted as 500–336 h, not only showed a decrease in tensile stress but also exhibited a highly increased elongation. Transmission electron microscopy and atom probe tomography were utilized to evaluate the precipitates distribution. The results showed that, in the case of 500–336 h sample, the fraction of precipitates with a radius over 10 nm is the highest and that of a few nano-sized precipitates is the lowest among all samples. It can be explained that the coarsening of originally nano-sized precipitates, occurred by diffusion of dissolved carbon in 500–336 h, mainly affects the tensile behavior.
KeywordsMetals Rolling Precipitation Tensile test Transmission electron microscopy (TEM)
The authors gratefully acknowledge the financial support from POSCO and the National Institute for Nanomaterials Technology (NINT), Korea.
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