Microstructural Influences on Young's Modulus for Fe‐V‐C and Fe‐Mo‐C Alloys

The Young modulus E exhibits a coefficient in the Hooke's law. It is influenced by external parameters as temperature, forming forces, forming velocity, delay time, static or dynamic straining, stress state in tension or compression, and by internal, material‐related parameters as chemical composition, textures, lattice defect contents and results of occurred diffusion processes. Iron‐base alloys and steels – as here on single‐phase to three‐phase Fe‐V‐C and Fe‐Mo‐C alloys – showed the dependence of E on the microstructure (grain size and phase arrangement). The influence of annealing temperature yields grain growth with corresponding grain sizes. From this an equilibrium ratio of E to a distinct grain size D̄ after heat treatment in the γ‐range of iron alloys, dependent on the concentration of alloying elements, is adjusted. Besides the equilibrium E/−ln D̄ also non‐equilibrium states occur, and therefore the possibilities exist to reduce the Young modulus till to a concentration‐dependent minimum (equilibrium), and to raise it into the non‐equilibrium stages. The influences of texture and remaining dislocation content are small. With the specific variation of E it is possible to improve the stiffness of thin steel sheet materials, preferred this is interesting for the car industry.