Bainite

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

Phase field modeling of microstructure evolution in steels

Abstract: This article provides an overview on the application of phase field models to describe microstructure evolution in steels. The focus will be on phase field modeling of the austenite–ferrite transformation as this has emerged as a particularly active area of research in the past few years. Phase field models are powerful tools to deal with the complex morphologies, e.g. Widmanstatten ferrite, that may result from these transformations. Even though much progress has been attained there is still significant work to be done in applying these models to processing of advanced steels with complex multi-phase microstructures. In particular, the phase field approach promises to have significant impact on modeling of bainite formation and the microstructure evolution in the heat affected zone of welds.

Development of microstructural banding in low-alloy steel with simulated Mn segregation

Abstract: The development of microstructural banding in low-alloy steel with Mn segregation has been investigated through the use of artificially segregated steel, interrupted cooling techniques, and optical microscopy. Mn segregation was simulated by hot roll bonding thin sheets of 5140 steel with 0.82 wt pct Mn and modified 5140M with 1.83 wt pct Mn into a plate with 20- and 160-µm-thick segregated layers. Samples were austenitized at 850 °C, continuously cooled at 1 °C/s and 0.1 °C/s, and quenched from progressively lower temperatures to observe the evolution of the microstructure. The segregated band thickness had a striking effect on microstructural development. Samples with 160 µm bands cooled at 1 °C/s had martensite and bainite in high-Mn bands. In contrast, samples with 20 µm bands cooled at the same rate had pearlite in high-Mn bands. The dramatic effect of band thickness on microstructural development was due to growth of a fully pearlitic band at the interface between segregated layers. The formation of interfacial pearlite is discussed relative to redistribution of carbon between adjacent high- and low-Mn bands during cooling.

Structu re-property relationships in commercial low-alloy bainitic-austenitic steel with high strength, ductility, and toughness

Abstract: A commercial low-alloy steel exhibiting combinations of mechanical properties superior to those of many other highly alloyed steels has been designed. The good properties are achieved by a carbide-free bainitic–austenitic structure, which can be produced by isothermal heat treatment of high-carbon silicon-alloyed steels in the upper bainite temperature range. Structure–property relationships are evaluated in order to find the optimum combination of heat treatment and alloy content. The effective grain size, the austenite volume fraction, and the austenite morphology are important factors controlling the properties. The mechanical stability of the austenite is of little importance.