Role of Tensile Pre-strain on Compression Creep of Alpha Brass

The creep behavior of pre-tensile strained alpha brass was investigated. The primary creep strain was increased by tensile pre-strain while secondary creep rate was little affected. Based on the stress exponent of 6.32 and the activation energy of 70.2 kJ/mol—obtained from the temperature and stress dependence of the secondary creep rate in the as-received specimen—the dominant creep mechanism was identified as either pipe diffusion-limited dislocation creep or dislocation glide hindered by forest dislocations. By combining the one-variable internal state variable model with creep model and also with back stress, it is suggested that −150 MPa of back stress can explain the increase of primary creep and similarity of secondary creep rate. The calculated results indicate that the back stress introduced by tensile pre-strain increases effective stress and thus creep strain rate in primary region. On the other hand, back stress becomes less significant in secondary region due to creep deformation.