Very Strong, Low–Temperature Bainite
ثبت نشده
چکیده
During the course of our research on the quantitative design of steels [1,2], an exciting discovery was made, in which carbide–free bainite was obtained by transformation at incredibly low temperatures, as low as 125 ◦C [3]. To put this into context, the random jump distance of an iron atom at that temperature is only 10 m over a period of three weeks. The consequence of the low transformation–temperature was to reduce the scale of the microstructure to such an extent, that it became possible to achieve a strength of 2300 MPa with signs of considerable ductility. The work described in what follows was carried out to understand and design this extraordinary bainite, which is incredibly strong, tough and cheap. The combination of properties achieved has never before been reported for bainite.
منابع مشابه
Very strong low temperature bainite
Bainite has been obtained by heat treatment at temperatures as low as 125°C in a high carbon, high silicon steel. This has had the effect of greatly re® ning the microstructure, which is found to have a strength in excess of 2.5 GPa together with an ability to ̄ ow plastically before fracture. Such properties have never before been achieved with bainite. In this paper metallographic details are ...
متن کاملBimodal Size-distribution of Bainite Plates
There are two well-known phenomena associated with the bainite reaction, both of which have been exploited here to enhance the mechanical behaviour of steel. Firstly, the bainite plate size decreases as the transformation temperature is reduced. Secondly, it is bad to have large regions of untransformed austenite in the microstructure; this is because they can transform, under the influence of ...
متن کاملTemperature cycling and the rate of the bainite transformation
There is a novel range of steels under development, based on bainite forming at exceptionally low temperatures. The advantage of suppressing the transformation temperature is that incredibly fine platelets of bainitic ferrite are generated which are only 20–40 nm in thickness. This makes the steel strong and in combination with the austenite that is retained, gives a useful range of properties ...
متن کاملDesigning low carbon, low temperature bainite
The possibility of producing bainite at low temperatures by suppressing transformation using substitutional solutes has been investigated, as an alternative to using large carbon concentrations to achieve the same purpose. It is found that although transformation temperatures can indeed be suppressed in this way, the difference between the bainite and martensite start temperatures diminishes. T...
متن کاملNew approach for the bainite start temperature calculation in steels
The bainite start temperature Bs is defined as the highest temperature at which ferrite can transform by a displacive transformation. A common observation is that the bainite start temperature is very sensitive to the chemical composition, indicating that the influence of solutes is more than just thermodynamic. Empirical linear regression models have long been used to calculate the Bs in a lim...
متن کامل