Thermodynamic analysis and model of low lattice misfit precipitates-induced twinning in cobalt-free ultra-strong/tough maraging steels

We describe here the thermodynamic analysis and model that governs low lattice misfit precipitate-induced nanoscale deformation twinning and the associated landscapes for twin nucleation and propagation in an ultrastrong-high toughness cobalt-free maraging steel that was recently studied by the author's group. The underlying reason for the study is that the traditional lower-strength cobalt-bearing maraging steels generally have semi-coherent precipitates, where the ductility is associated with dislocation slip. It is underscored that coherent precipitates facilitate twin nucleation during deformation provided they generate a resolved shear component on the active twin system.