PSI - Issue 40

A.M. Povolotskaya et al. / Procedia Structural Integrity 40 (2022) 359–364 A.M. Povolotskaya, A.N. Mushnikov / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 5. The dependence  d max (ε) .

Figure 6a shows the linear longitudinal magnetostriction  as dependent on the applied magnetic field for specimens tested for plastic tension to different levels. For the initial state specimen (ε = 0), as the magnetic field strength increases, the longitudinal magnetostriction first increases to a maximum, then decreases, reaches zero, and continues to decrease, now with a negative sign (curve 1 in Fig. 6a). For specimens subjected to plastic deformation (curves 2 to 7 in Fig. 6a), the following change is observed in the field dependence of magnetostriction: at all the values of magnetic field strength,  ( Н ) is positive. As ε increases to 1.96 %, the area of the positive part of the field dependence of magnetostriction significantly increases and, as can be seen in Fig. 6b, the magnetostriction maximum  max signi ficantly increases. As ε further increases from 1.96 % to 7.53 %, the area of the positive part of the field dependence of magnetostriction and the value of its maximum remain practically unchanged, and begin to decrease after ε reaches 10 %. a b

Fig. 6. (a) – the dependences  ( Н ) for the specimens plastically deformed to different plastic strain values ε: 0 (curve 1), 0.75 (2), 1.28 (3), 1.96 (4), 5.01 (5), 7.53 (6), 10 % (7); (b) – the dependence  max (ε) .

The behavior of  ( Н ) for the specimens subjected to plastic deformation up to ε = 7.5 % corresponds to the behavior of magnetostriction curves under uniaxial static compression, see in Anderson et al. (2007), Gorkunov et al. (2013), Dias and Landgraf (2020), Wun-Fogle et al. (2009), Makar and Tanner (2000), and it is due to the same reasons as given above, namely the appearance of residual compressive stresses of different levels in the direction of plastic deformation and the formation of the “easy magnetization plane” texture. At ε = 10 %, the value of  max decreases. Apparently, this is due to the fact that the level of residual compressive stresses, having reached its limiting value (saturation), begins to decrease with strains ε ≈10 %. 4. Conclusion The regularities of all the investigated magnetic characteristics of the 20GN hull steel plastically deformed by tension to various levels, confirm the appearance of the “easy magnetization plane” texture in the specimens. This is