Usually, tool steels are used in quenched and tempered condition. Due to the phase transition from austenite to martensite and the volume change during the transformation, controlling of distortion might be a challenge. The end user’s demand for high hardness of the final tool leads to a poor machinability.
Engineering steels with bainitic structure are generally based on a low alloying content due to economic reasons, especially the carbon content is rather low compared to tool steels. Bainitic steels require often a controlled cooling to get the desired microstructure and the maximum size to achieve a fully homogeneous bainitic structure is limited to a dimension far below acceptable dimensions of tool steels.
A newly developed steel focusing on a bainitic structure even for bigger dimensions shows a lower hardness at ambient temperature than conventional hot working tool steels, but with a lower temperature dependency. Therefore, at service temperature the mechanical properties are comparable to established grades. Heat treatment is simplified by a simple austenitization and cooling process without special requirement on the cooling rate. Due to a generally lower cooling rate and lower hardness compared to a Q&T process the risk of cracking is reduced, while machinability is improved.
With the combination of good weldability and rather low hardness after rapid cooling, this grade can also be processed in additive manufacturing and is well-suited for a hybrid process of conventional and additive manufacturing.