Bainite frequently occurs in alloy steels during quenching to form martensite. The cooling rate towards the centre of a steel bar is lower than the outside, so in large sections bainite can form in the inner regions with martensite predominating towards the surface.

However, low carbon fully bainitic steels have been developed, as described, using 0.5% Mo and very small concentrations of boron, which allow bainite to form over a wide range of cooling rates. Further control of the reaction is obtained by use of metallic alloying elements such as Ni, Cr, Mn which depress the temperature of maximum rate of formation of bainite. As the transformation temperature is lowered, for a constant cooling rate, the strength of the steel increases substantially. For a series of steels with 0.2% C the tensile strength can be varied between 600 and 1200 MPa. However, this increase in strength is accompanied by a loss of ductility.

The practical advantage of bainitic steels is that relatively high strength levels together with adequate ductility can be obtained without further heat treatment, after the bainite reaction has taken place. The steels are readily weldable, because bainite rather than martensite, will form in the heat-affected zone adjacent to the weld metal, and so the incidence of cracking will be reduced. Furthermore, the steels have a low carbon content, which improves the weldability and reduces stresses arising from transformation.