CEMENTITE PRECIPITATION DURING TEMPERING OF MARTENSITE UNDER THE INFLUENCE OF AN EXTERNALLY APPLIED STRESS

The precipitation of cementite under the influence of an externally ap plied stress, during the tempering of martensite in steels, is investi gated using transmission electron microscopy. The stress appears to fa vour the development of particular crystallographic variants of cement ite in any given plate of martensite. Hence, a Widmanstatten 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 precipitatio n during the lower bainite reaction.