Abstract
The precipitation of cementite under the influence of an externally applied stress, during the tempering of martensite in steels, is investigated using transmission electron microscopy. The stress appears to favour the development of particular crystallographic variants of cementite in any given plate of martensite. Hence, a Widmanstätten array of cementite particles in a normally tempered sample changes to an array consisting of just one variant in stress-tempered samples. The results are discussed in the context of the mechanism of carbide precipitation during the lower bainite reaction.
This research paper investigates how external mechanical stress affects the formation of cementite particles during the heat treatment of martensitic steel. The authors utilise transmission electron microscopy to demonstrate that applying pressure during tempering forces the carbide to grow in a single orientation rather than a complex multidirectional array.
This phenomenon is explained through a displacive transformation mechanism, where the applied stress provides a mechanical driving force that favours specific structural variants. By analysing different levels of compression, the study concludes that higher stress levels more effectively restrict carbide precipitation to a lone variant.
These findings support a paraequilibrium model of growth and offer insights into similar metallurgical reactions observed in lower bainite.
Journal of Materials Science, 1994, Vol. 29, No. 23, pp. 6079–6084
