Coalesced bainite is a coarse constituent recently found to develop along with the classical martensite, lower and upper bainite in steel weld metals. Its crystallography has been characterised using electron backscattering diffraction in combination with field emission gun scanning electron microscopy. It is confirmed that coalesced bainite grains are crystallographically homogeneous but do co...

Two experimental high strength steel weld metals were produced with 7 wt-% nickel and either 2 or 0.5 wt-% manganese. Neural network predictions that it is advantageous to reduce the manganese concentration in high nickel alloys have been confirmed, with impact energy increasing from 32 to 113 J at –40uC. High resolution microstructural investigations showed that both weld metals contained main...

There has long existed a controversy regarding the formation of the bainite phase in steels. Nonetheless, following the clear identification of bainite in 1930, several characteristic features associated with the bainite transformation became well established. These features include: the classification into upper and lower bainite; the existence of a bainite-start temperature; and the incomplet...

Two experimental high strength steel weld metals were produced with 7 wt. % nickel and manganese at 2 or 0.5 wt. %. Neural network predictions that Mn reductions increase toughness were confirmed with impact energy increasing from 32 to 113 J at –40 °C. High resolution microstructural investigations showed that both weld metals contained mainly martensite at interdendritic regions and predomina...

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 of carbon in the films of austenite ac...

The mechanism of the bainite transformation in carbon containing steels was discussed after presenting our recent experimental results; (1) the bainite transformation has its own C-curve, (2) incomplete phenomenon is a general feature of the bainite transformation, (3) bainitic fenite grows to a limited size, and (4) bainitic ferrite is highly supersaturated with respect to carbon. It was exami...

The strength of mixed microstructures of bainite and martensite can peak at an intermediate volume fraction of martensite has been published by recently experimental studies. A quantitative interpretation of these observations is achieved by modelling the mechanical properties of mixed microstructures of bainite and martensite. The peak in the curve of the strength as a function of the volume f...

: Consistent with the wishes of the Conference Organisers, the basic theory of the bainite reaction including the crystallographic, thermodynamic and kinetic framework is described, together with the development of fine bainite and its properties.

A coarse grained constituent recently discovered in high strength steel weld metals – Coalesced Bainite – was investigated with a serial section procedure for three-dimensional (3D) analysis using Focused Ion Beam (FIB) milling. Image planes of a coalesced bainite grain, 0.4 μm apart were acquired using the FIB. The data collected was then used to create a 3D model of the coalesced bainite grai...

An experimental high strength steel weld metal containing 7 wt. % nickel and 2 wt. % manganese was found to have a complex microstructure. Employing high resolution characterisation techniques the microstructure consisted primarily of a mixture of martensite, upper bainite and a novel constituent with large grain size that contained plate-like precipitates. This constituent was characterised to...