The effect of carbide morphology and distribution on the uniaxial deformation of iron-carbon-X alloys

Precipitate distribution effects on the uniaxial deformation in ferrite/martensite aggregates have been investigated in four Fe-C-X (X = Mn, Mo, V, W) alloys. The austenite decomposition reactions of Fe-C-W alloys have received relatively little attention compared to other alloying additions. It was found that the resulting ferrite morphology and martensite distribution resembled that found in Fe-C-Mo alloys; however, the carbides were much coarser with a variety of distributions. A series of microstructures was obtained in the four alloys consisting of ferrite with varying distributions of alloy carbides in association with islands of martensite or pearlite colonies.; TEM investigations reveal that a dislocation cell structure is formed in the "clean" ferrite, that is ferrite with no alloy carbides, while the presence of alloy carbides inhibit the formation of dislocation cells. TEM and SEM investigations reveal that strain inhomogeneities occur in conjunction with the carbides, leading to void formation and failure. A study on the effect of martensite on ferrite deformation revealed that although plastic constraint can occur because of local geometry, the major affect of the martensite is to increase the effective strain in the ferrite by forcing it to accommodate the majority of the applied strain.