Influence of segregated transition metals on intergranular brittleness of tempered martensitic steels

The transition metals Mn, Ni, Mo, and Cr which cosegregate with the impurities to the grain boundaries of temper brittle steels alter the embrittlement associated with the segregation of these impurities. This ‘mechanical’ effect of metallic additives, which can be harmful (Mn, Ni) or beneficial (Mo), is comparable in magnitude to their ‘thermochemical’ effect, associated with the variations in impurity segregation arising from the chemical interactions between the two types of elements.