Thermodynamics of nanocrystilline formation in surface layer of Hadfield steel by shot peening

Conventional shot peening tests of Hadfield steel have shown that a nanostructured grains layer can be easily produced. Theoretically, nanostructure formation thermodynamics becomes an important issue to coarse grains transformating into nanocrystalline. In the present paper, thermodynamics of strain induced nanosized microstructure in Hadfield steel after shot peening was discussed based on Pringogine's nonequilibrium thermodynamics and Miedema semi-experimental theory. It was concluded that the difference of Gibbs free energy should be at least increased to 0.1380 kJ/mol in the alloy system by strain hardening, compared to the previous Gibbs energy before the treatment.