Magnetic Effect of Young’s Modulus in High Manganese Austenitic Steels and Change with Hydrogen Charging

Young’s moduli of two kinds of high manganese austenitic steels, 18Mn-4Cr and 15Mn-17Cr steels, were measured by the resonance method of free-free transverse vibration. In both engineering steels, the temperature dependence of Young’s modulus showed a remarkable anomaly, that is, an abrupt drop near the Néel temperature TN and a successive lowering below TN, as has been reported in some antiferromagnetic alloys. Such elastic softening may be considered to originate from the generation of magnetostriction in the antiferromagnetic range below TN. In particular, the abrupt drop of Young’s modulus of the 18Mn-4Cr steel was extremely large compared to those reported in the literature. Hydrogen charging did not affect the anomaly but caused a slight increase in Young’s modulus over the entire temperature range examined.