Bainite

About: Bainite is a research topic. Over the lifetime, 9520 publications have been published within this topic receiving 145305 citations.

Nucleation theory for high-carbon bainite

Abstract: There is a great deal of interest in high-carbon (≥0.8 wt.%) bainite, both in the context of cast irons and in the development of novel very strong and tough steels. In this paper we investigate whether the theory describing the nucleation of bainite is appropriate for this new class of materials.

Effect of microstructure on mechanical properties of isothermally bainite-transformed 300M steel

Abstract: A study has been made of the effect of the microstructure on the mechanical properties of commercial-aircraft quality 300M steel which has been isothermally transformed in various bainitic temperature regions (593–673 K) after austenitization at 1173 K. The results were compared with those obtained by conventional quenching and tempering. Isothermal transformation of the steel at and below 623 K produced a dispersion of retained austenite (12–18 vol.%) in a carbon-free upper bainite matrix. The treatment improved the K I c value, owing to an increase in the Charpy impact energy; however, no improvement in strength was observed. As aresult of the isothermal transformation at and above 648 K, the retention of a large amount of retained austenite (22–25 vol.%) was encouraged, in conjunction with carbon-free upper-bainite; however, this was found to have a very detrimental effect on the strength and toughness. The results are described and discussed in terms of the microstructure and fractography.

Prediction of mechanical properties of multi-phase steels based on stress-strain curves

Abstract: An approach to predict mechanical properties of hot-rolled multi-phase steels referring to the stress-strain curves is proposed. Different from a conventional approach of regression analysis about the relationships between properties and chemical compositions and processing factors, a proposed one is based on the analysis and application of stress-strain curve: several commonly used mechanical properties such as yield strength, tensile strength, uniform elongation, total elongation, work-hardening exponent (n) and Vickers hardness, are derived systematically from the stress-strain curve of a multi-phase steel, which is calculated by using concentration factor, i.e., strain partition ratio and stress-strain curves of constituent phases. Stress-strain curves of individual component structures such as ferrite, pearlite, bainite, and martensite are expressed by Swift's equation. Physical background of the concentration factor is discussed by examining theoretical models of deformation for two-phase materials. Evaluation of plastic relaxation related to microstructural topology might be the most difficult point of this approach and some trials are presented.