H. K. D. H. Bhadeshia

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There are difficult problems in materials science where the general concepts might be understood but which are not as yet amenable to scientific treatment. We are at the same time told that good engineering has the responsibility to reach objectives in a cost and time–effective way. Any model which deals with only a small part of the required technology is(More)
Friction stir welding is a refreshing approach to the joining of metals. Although originally intended for aluminium alloys, reach of FSW has now extended to a variety of materials including steels and polymers. This review deals with the fundamental understanding of the process and its metallur-gical consequences. The focus is on heat generation, heat(More)
Recent changes in the design of steam turbine power plant have necessitated the replacement of bolted ¯anges with welded joints. The design process therefore requires a knowledge of the creep rupture strength of the weld metal consumed in the welding process. This paper presents a method which can be used to estimate the creep rupture strength of ferritic(More)
The carbon concentration trapped in films of austenite between parallel platelets of bainite is often found to be much larger than that in the larger blocks of austenite between sheaves of bainite. The effect of this non-uniform distribution of carbon on the overall transformation kinetics of bainite is examined theoretically. It is found that the trapping(More)
Bainitic microstructures in which fine platelets offerrite are intimately mixed with films of austenite are known to exhibit good combinations of strength and toughness. It isfound that the thickness of these austenitefilms can be estimated by assuming that the carbon diffusion field around an existing plate offerrite prevents the close approach of another(More)
We have constructed a Bayesian neural network model that predicts the change, due to neutron irradiation, of the Charpy ductile-brittle transition temperature (ΔDBTT) of low activation martensitic steels given a 40-dimensional set of data from the literature. The irradiation doses were < 100 displacements per atom (dpa). Results show the high significance(More)
Bainite forms by the decomposition of austenite at a temperature which is above M S but below that at which fine pearlite forms. All bainite forms below the T 0 temperature. All time–temperature–transformation (TTT) diagrams consist essentially of two C–curves (Fig. 1). If we focus first on the Fe–Mn–C steel with the higher hardenability (slower rates of(More)
It is possible to create bainite in the form of long, slender crystals of ferrite whose scale compares with that of carbon nanotubes. These crystals are about 200Å in thickness and are generated by the partial transformation of austenite. The result is an extraordinary combination of strength and toughness; the bainite has the highest hardness and lowest(More)
Residual stress is that which remains in a body that is stationary and at equilibrium with its surroundings. It can be very detrimental to the performance of a material or the life of a component. Alternatively, beneficial residual stresses can be introduced deliberately. Residual stresses are more difficult to predict than the in-service stresses on which(More)