The relationship between alloying content, microstructure and properties has been studied for high strength steel weld metals with 7 to 9 wt. % nickel. Neural network modelling suggested that manganese reductions lead to large impact toughness increases and that nickel must be added in a controlled manner with respect to manganese in order toincrease impact toughness. Carbon additions were pred...

We investigated the effects of the additions of Zr and other alloying elements on the mechanical properties and microstructure in Cr-Mo plastic mold steels. The addition of alloying elements changed the microstructure of the normalized samples from the upper bainite to lower bainite due to the increased hardenability. The tempering temperature influenced the strength and hardness values, especi...

Examination of a time–temperature–transformation (TTT) diagram for an eutectoid carbon steel (Fig. 1), bearing in mind the fact that the pearlite reaction is essentially a high temperature one occurring between 550C and 720C and that the formation of the martensite is a low-temperature reaction, reveals that there is a wide range of temperature ∼250–550C within which neither of these phases for...

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 ...

Microstructure and properties have been studied for high strength steel weld metals with variations in carbon, manganese and nickel. Based on neural network modelling, experimental welds were made using shielded metal arc welding with manganese at 0.5 or 2.0 wt. % and nickel at 7 or 9 wt. %. Additional welds were made where carbon was varied between 0.03 and 0.11 wt. %. Generally there was very...

A theory is developed for the evolution of bainite as a function of time, temperature, chemical composition and austenite grain size. The model takes into account the details of the mechanism of transformation, including the fact that nucleation begins at the austenite grain surfaces, and that the growth of a sheaf occurs by the repeated nucleation of small platelets. Predictions made using the...

There is a novel steel invented in which the structure consists of extremely fine platelets of bainitic ferrite dispersed in a matrix of carbon enriched retained austenite. The resulting large density of interfaces makes the alloy very strong in its transformed condition. The authors report the first fatigue tests on this system, by measuring the life of parallel gauged samples tested using cyc...

High silicon (>1.5%) steels with different compositions were isothermally transformed to bainite at 220 and 250 ◦C to produce what is often referred to as nanostructured bainite. Interrupted tensile tests were carried out and the retained austenite was measured as a function of strain. Results were correlated with tensile ductility. The role of retained austenite stability is remarkably underli...

A PM approach is investigated in the context of extremely fine low temperature bainitic steels with a reasonable combination of ultimate tensile strength and uniform elongation. The strategy consists of three steps. First, ball milling is used for mechanical alloying and to create a large density of interfaces prior to sintering. In the second step, spark plasma sintering is used as a rapid con...