Abstract：The strain hardening behaviour of five TWIP steels with different Mn content was investigated by static tensile test and metallography. The results show that Hollomond relationship is inapplicable. The n value of No.1 steel was increased first and then decreased with increasing true strain. However, the n value of other steels was increased with increasing true strain. Moreover, for the same steel, the n value was increased with increasing strain rate. The micro mechanisms are:with the increase of Mn content, formation of the twin will gradually play a leading role. There are many annealing twins before tension. With the development of deformation, many deformation twins are formed. The interaction between twins and dislocations are coordinated with strain hardening rate. Subsequently, the necking is delayed and the ability of uniform deformation is obtained.
2007, Vol. 42 
