The attainment of ultra®ne ferrite grain structures in low carbon, low alloy steels is of interest because of the improvement in yield strength and Charpy impact transition temperature predicted by extrapolation of known data to very ®ne grain sizes. This paper presents a summary of research aimed at producing ultra®ne ferrite in a niobium microalloyed, low carbon steel by three processing routes. Transformational grain re®nement (TGR), in which extra®ne austenite is hot rolled and cooled rapidly, has been shown to be capable of producing grain sizes of v1 mm in a surface layer, and 1 . 5 mm in the centre of 3 mm thick plate. Dynamic recrystallisation of ferrite during multipass warm rolling was shown to be neither complete nor uniform within the cross-section of the plate. Nevertheless, a partly recrystallised, partly recovered grain structure with an average grain size of 1 . 5 mm was obtained in the centre of 3 mm thick plate. Cold rolling and recrystallisation of ferrite that had been previously re®ned by TGR to an intermediate grain size was shown to produce an ultra®ne grain microstructure (v1 mm grain size) throughout the section of 1 mm thick strip. The hardness of ultra®ne ferrite was shown to obey a linear relationship with the inverse square root of grain size, but with a lower slope than expected from the Petch relationship for yield strength.MST/4772
An efficient route to AZD4635 has been developed utilizing the Suzuki−Miyaura reaction of a boronate ester prepared by C−H borylation on a multikilogram scale. Preparation of the cross-coupling partner using bromine/pyridine/ methanol has highlighted the incompatibility of this reagent/solvent combination with tantalum, which is commonly used in the construction and repair of standard manufacturing vessels.
The production of functional tool steel components by selective laser sintering requires an understanding of the effects of the laser processing parameters on the microstructure evolution during the fabrication process. This would allow the production of tools that have predictable and reproducible microstructure, good mechanical properties and low residual stresses. In this paper, finite element modelling has been carried out to investigate the temperature distribution and residual stresses during laser sintering of hot-work tool steel powders. The effects of the laser power and scanning rate on the selective laser sintering process have been investigated. Thermal residual stresses accumulated during the process have been predicted and compared with strain measurements made using neutron diffraction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.