Effect of cold working deformation on the internal friction of 2.25Cr–1Mo steel

With the forced flexural oscillation, the internal friction of cold working 2.25Cr–1Mo steel was measured on a dynamic mechanical analyzer (DMA). Over the range of variables (temperature and frequency) normally encountered in service applications, the experimental results show that the internal friction of 2.25Cr–1Mo steel at temperatures from 740 K to 823 K is strongly sensitive to the magnitude of cold working deformation. According to analyses of the obtained results, it indicated that within the applied stress, the internal friction of cold working 2.25Cr–1Mo steel in this temperature range is a thermally activated relaxation, which is mainly attributed to the diffusion-controlled motion of dislocation. Thus, the internal friction of 2.25Cr–1Mo steel is dependent on not only the temperature, but also the frequency. Besides, the cold working deformation primarily leads to the considerable change of dislocation configuration.

Research highlights▶ In this study, the internal friction of cold-working 2.25Cr–1Mo steels was measured on a dynamic mechanical analyzer (DMA). Over the range of variables (temperature and frequency) normally encountered in service applications, the experimental results show that the internal friction of 2.25Cr–1Mo steel at temperatures from 740 K to 823 K is strongly sensitive to the magnitude of cold working deformation. According to analyses of the obtained results, it indicated that within the applied stress, the internal friction of cold working 2.25Cr–1Mo steel in this temperature range is a thermally activated relaxation, which is mainly attributed to the diffusion-controlled motion of dislocation. Thus, the internal friction of 2.25Cr–1Mo steel is dependent on not only the temperature, but also the frequency. Besides, the cold working deformation primarily leads to the considerable change of dislocation configuration, which makes it possible to evaluate the creep state of elevated temperatures with the measurement of internal friction.