AbstractThe Young's modulus of transition metal carbides has been calculated from their assessed thermal properties to explain why the modulus of steels and white cast irons can be only marginally altered by changes in composition or heat treatment. It is shown that the modulus of cementite (200 GN m−2) is virtually identical to the value calculated for pure ferrite (215 GN m−2). The predicted systematic variation for the modulus both with structure and position in the periodic table rationalises previous isolated experimental observations and confirms that the MC carbides of the group IV elements should have the most powerful strengthening effect in a matrix of their parent metal.MST/1909