AbstractThe characteristics of serrated yielding (the Portevin–Le Chatelier effect) in a Nb–V dual phase steel have been studied in the temperature range 85–210°C at strain rates between 1·2×10−5and 1·2×10−2s−1. Serrated yielding was found to initiate only after a critical strainɛcwas reached. The strain between two successive serrations∆ɛsincreases almost linearly with strain, while the stress drop∆σcincreases with strain up to∆σmax, then decreases. The exponentβin the mobile dislocation density–plastic strain relationship (ρm=ɛβ) is 1·09 in the temperature range 85–140°C and 1·34 in the temperature range 140–210°C. The results also indicate that in the same temperature ranges there are two values of activation energy for type A serrations, i.e. 79 and 119 kJ mol−1respectively. The results are discussed in terms of substitutional–interstitial solute atom interaction and changes of concentration of interstitial atoms.MST/934