Tensile, fracture, and fatigue crack growth rate behavior of high manganese steels

Mechanical low temperature investigations were carried out to determine the cryogenic mechanical properties of newly developed Fe-Cr-Mn alloys with contents of chromium between 5 % and 10 % and manganese between 30 % and 40 % under the Project G-811, Russia. The final products were forged, rolled, and solution heat treated to obtain appropriate plate sizes necessary for the mechanical measurements. The tensile properties of these alloys determined between 4 K and 7 K show for certain alloy combination high elongation values at fracture of greater than 50 % with considerable high yield strengths around 900 Mpa. The measured fracture toughness values with small scale compact tension specimens using elastic plastic J-tests show K-IC data between 100 MPa root m and 220 MPa root m according to the alloy combination. Fatigue crack growth rate (FCGR) measurements of these alloys result also in some alloy combination case, high resistance against crack propagation with measured Paris coefficients of m similar to 5 and C similar to 8.5 E-13 mm/cycle. Thermal expansion of these alloys has been also determined resulting in values between 1600 mu m/m and 1700 mu m/m expansion from 5 K to 290 K.